dr inż. Michał Maj

Zakład Mechaniki Materiałów (ZMM)
Laboratorium Termoplastyczności (LT)
stanowisko: specjalista
telefon: (+48) 22 826 12 81 wew.: 177
pokój: 223
e-mail: mimaj

Rozprawa doktorska
2007-10-04Wpływ kierunku wstępnego odkształcenia na proces magazynowania energii w polikryształach 
promotor -- prof. dr hab. inż. Wiera Oliferuk, IPPT PAN
604
 
Kierownik projektów
1. Eksperymentalna analiza sprzężeń termomechanicznych w mikroskali podczas deformacji plastycznej polikryształów, Badania własne, Okres realizacji od 2013-06-27 do 2016-06-26, Finansowanie: NCN, SONATA 4, UMO-2012/07/D/ST-8/02665

Ostatnie publikacje
1.Golasiński K.M., Pieczyska E.A., Staszczak M., Maj M., Furuta T., Kuramoto S., Infrared thermography applied for experimental investigation of thermomechanical couplings in Gum Metal, Quantitative InfraRed Thermography Journal, ISSN: 1768-6733, DOI: 10.1080/17686733.2017.1284295, pp.1-8, 2017
Golasiński K.M., Pieczyska E.A., Staszczak M., Maj M., Furuta T., Kuramoto S., Infrared thermography applied for experimental investigation of thermomechanical couplings in Gum Metal, Quantitative InfraRed Thermography Journal, ISSN: 1768-6733, DOI: 10.1080/17686733.2017.1284295, pp.1-8, 2017

Abstract:
Results of initial investigation of thermomechanical couplings in innovative β-Ti alloy called Gum Metal subjected to tension are presented. The experimental set-up, consisting of testing machine and infrared camera, enabled to obtain stress–strain curves with high accuracy and correlate them to estimated temperature changes of the specimen during the deformation process. Both ultra-low elastic modulus and high strength of Gum Metal were confirmed. The infrared measurements determined average and maximal temperature changes accompanying the alloy deformation process, allowed to estimate thermoelastic effect, which is related to the alloy yield point. The temperature distributions on the specimen surface served to analyse strain localization effects leading to the necking and rupture.

Keywords:
Gum Metal, thermomechanical coupling, nonlinear elasticity, yield point, infrared camera

25p.
2.Pieczyska E.A., Staszczak M., Maj M., Kowalczyk-Gajewska K., Golasiński K., Cristea M., Tobushi H., Hayashi S., Investigation of thermomechanical couplings, strain localization and shape memory properties in a shape memory polymer subjected to loading at various strain rates, SMART MATERIALS AND STRUCTURES, ISSN: 0964-1726, DOI: 10.1088/0964-1726/25/8/085002, Vol.25, No.8, pp.085002-1-15, 2016
Pieczyska E.A., Staszczak M., Maj M., Kowalczyk-Gajewska K., Golasiński K., Cristea M., Tobushi H., Hayashi S., Investigation of thermomechanical couplings, strain localization and shape memory properties in a shape memory polymer subjected to loading at various strain rates, SMART MATERIALS AND STRUCTURES, ISSN: 0964-1726, DOI: 10.1088/0964-1726/25/8/085002, Vol.25, No.8, pp.085002-1-15, 2016

Abstract:
This paper presents experimental and modeling results of the effects of thermomechanical couplings occurring in a polyurethane shape memory polymer (SMP) subjected to tension at various strain rates within large strains. The SMP mechanical curves, recorded using a testing machine, and the related temperature changes, measured in a contactless manner using an IR camera, were used to investigate the polymer deformation process at various loading stages. The effects of thermomechanical couplings allowed the determination of the material yield point in the initial loading stage, the investigation of nucleation and development of the strain localization at larger strains and the estimation of the effects of thermoelastic behavior during the unloading process. The obtained stress–strain and thermal characteristics, the results of the dynamic mechanical analysis and estimated values of the shape fixity and shape recovery parameters confirmed that the shape memory polymer (T g = 45°C) is characterized by good mechanical and shape memory properties, as well as high sensitivity to the strain rate. The mechanical response of the SMP subjected to tension was simulated using the finite element method and applying the large strain, two-phase model. Strain localization observed in the experiment was well reproduced in simulations and the temperature spots were correlated with the accumulated viscoplastic deformation of the SMP glassy phase.

Keywords:
shape memory polymer, thermomechanical coupling, infrared camera, tension test, strain rate, strain localization, constitutive model

40p.
3.Staszczak M., Pieczyska E., Maj M., Kukla D., Tobushi H., Infrared thermographic analysis of shape memory polymer during cyclic loading, MEASUREMENT SCIENCE AND TECHNOLOGY, ISSN: 0957-0233, DOI: 10.1088/0957-0233/27/12/124007, Vol.27, No.12, pp.124007-1-6, 2016
Staszczak M., Pieczyska E., Maj M., Kukla D., Tobushi H., Infrared thermographic analysis of shape memory polymer during cyclic loading, MEASUREMENT SCIENCE AND TECHNOLOGY, ISSN: 0957-0233, DOI: 10.1088/0957-0233/27/12/124007, Vol.27, No.12, pp.124007-1-6, 2016

Abstract:
In this paper we present the effects of thermomechanical couplings occurring in polyurethane shape memory polymer subjected to cyclic tensile loadings conducted at various strain rates. Stress–strain characteristics were elaborated using a quasistatic testing machine, whereas the specimen temperature changes accompanying the deformation process were obtained with an infrared camera. We demonstrate a tight correlation between the mechanical and thermal results within the initial loading stage. The polymer thermomechanical behaviour in four subsequent loading-unloading cycles and the influence of the strain rate on the stress and the related temperature changes were also examined. In the range of elastic deformation the specimen temperature drops below the initial level due to thermoelastic effect whereas at the higher strains the temperature always increased, due to the dissipative deformation mechanisms. The difference in the characteristics of the specimen temperature has been applied to determine a limit of the polymer reversible deformation and analyzed for various strain rates. It was shown that at the higher strain rates higher values of the stress and temperature changes are obtained, which are related to higher values of the polymer yield points. During the cyclic loading a significant difference between the first and the second cycle was observed. The subsequent loading-unloading cycles demonstrated similar sharply shaped stress and temperature profiles and gradually decrease in values.

Keywords:
thermomechanical couplings, infrared camera, shape memory polymer, tension, strain rate, thermoelastic effect, yield point

30p.
4.Pieczyska E.A., Maj M., Kowalczyk-Gajewska K., Staszczak M., Gradys A., Majewski M., Cristea M., Tobushi H., Hayashi S., Thermomechanical properties of polyurethane shape memory polymer–experiment and modelling, SMART MATERIALS AND STRUCTURES, ISSN: 0964-1726, DOI: 10.1088/0964-1726/24/4/045043, Vol.24, pp.045043-1-16, 2015
Pieczyska E.A., Maj M., Kowalczyk-Gajewska K., Staszczak M., Gradys A., Majewski M., Cristea M., Tobushi H., Hayashi S., Thermomechanical properties of polyurethane shape memory polymer–experiment and modelling, SMART MATERIALS AND STRUCTURES, ISSN: 0964-1726, DOI: 10.1088/0964-1726/24/4/045043, Vol.24, pp.045043-1-16, 2015

Abstract:
In this paper extensive research on the polyurethane shape memory polymer (PU-SMP) is reported, including its structure analysis, our experimental investigation of its thermomechanical properties and its modelling. The influence of the effects of thermomechanical couplings on the SMP behaviour during tension at room temperature is studied using a fast and sensitive infrared camera. It is shown that the thermomechanical behaviour of the SMP significantly depends on the strain rate: at a higher strain rate higher stress and temperature values are obtained. This indicates that an increase of the strain rate leads to activation of different deformation mechanisms at the micro-scale, along with reorientation and alignment of the molecular chains. Furthermore, influence of temperature on the SMP's mechanical behaviour is studied. It is observed during the loading in a thermal chamber that at the temperature 20°C below the glass transition temperature (Tg) the PU-SMP strengthens about six times compared to the material above Tg but does not exhibit the shape recovery. A finite-strain constitutive model is formulated, where the SMP is described as a two-phase material composed of a hyperelastic rubbery phase and elastic-viscoplastic glassy phase. The volume content of phases is governed by the current temperature. Finally, model predictions are compared with the experimental results.

Keywords:
shape memory polyurethane, thermomechanical couplings, infrared camera, temperature change, dynamic mechanical analysis, strain rate, constitutive model

40p.
5.Oliferuk W., Maj M., Zembrzycki K., Determination of the Energy Storage Rate Distribution in the Area of Strain Localization Using Infrared and Visible Imaging, EXPERIMENTAL MECHANICS, ISSN: 0014-4851, DOI: 10.1007/s11340-013-9819-1, Vol.55, pp.753-760, 2015
Oliferuk W., Maj M., Zembrzycki K., Determination of the Energy Storage Rate Distribution in the Area of Strain Localization Using Infrared and Visible Imaging, EXPERIMENTAL MECHANICS, ISSN: 0014-4851, DOI: 10.1007/s11340-013-9819-1, Vol.55, pp.753-760, 2015

Abstract:
The presented work is devoted to a new simple method of determination of the energy storage rate (the ratio of the stored energy increment to the plastic work increment) that allows obtaining distribution of this quantity in the area of strain localization. The method is based on the simultaneous measurements of the temperature and displacement distributions on the specimen surface during a tensile deformation. The experimental procedure involves two complementary techniques: i.e. infrared thermography (IRT) and visible light imaging. It has been experimentally shown that during the evolution of plastic strain localization the energy storage rate in some areas of the deformed specimen drops to zero. It can be treated as the plastic instability criterion.

Keywords:
Infrared thermography, Energy storage rate distribution, Strain localization, Plastic instability criterion, Texture evolution

30p.
6.Wysocka-Fotek O., Maj M., Oliferuk W., Use of pulsed IR thermography for determination of size and depth of subsurface defect taking into account the shape of its cross-section area, ARCHIVES OF METALLURGY AND MATERIALS, ISSN: 1733-3490, DOI: 10.1515/amm-2015-0181, Vol.60, No.2, pp.615-620, 2015
Wysocka-Fotek O., Maj M., Oliferuk W., Use of pulsed IR thermography for determination of size and depth of subsurface defect taking into account the shape of its cross-section area, ARCHIVES OF METALLURGY AND MATERIALS, ISSN: 1733-3490, DOI: 10.1515/amm-2015-0181, Vol.60, No.2, pp.615-620, 2015

Abstract:
The paper is devoted to reconstruction of size and depth (distance from the tested surface) of artificial defects with square and rectangular cross-section areas using the pulsed IR thermography. Defects in form of flat-bottom holes were made in austenitic steel plate. The defect size was estimated on the basis of surface distribution of the time derivative of the temperature. In order to asses the depth of defects with considered geometries on the basis of calibration relations (i.e. dependence of time of contrast maximum vs. defect depth for given defect diameter) obtained for circular defects, the ‘equivalent diameter’ describing not only the defect cross-section area but also its shape was assigned. It has been shown that presented approach gives satisfactory results.

Keywords:
pulsed IR thermography, defect size, defect depth, cross-section shape of defect

30p.
7.Pieczyska E.A., Staszczak M., Maj M., Tobushi H., Hayashi S., Investigation of thermal effects accompanying tensile deformation of Shape Memory Polymer PU-SMP, Measurement Automation Monitoring, ISSN: 0032-4140, Vol.61, No.6, pp.203-205, 2015
Pieczyska E.A., Staszczak M., Maj M., Tobushi H., Hayashi S., Investigation of thermal effects accompanying tensile deformation of Shape Memory Polymer PU-SMP, Measurement Automation Monitoring, ISSN: 0032-4140, Vol.61, No.6, pp.203-205, 2015

Abstract:
Experimental results of effects of thermomechanical couplings occurring in shape memory polymer subjected to tension are presented. Stress-strain curves were recorded by testing machine, while their related temperature changes were measured with infrared camera. The mechanical and thermal characteristics were used to investigate the polymer properties. Three various stages were distinguished during the deformation process. The first, elastic, is accompanied by a drop in the specimen temperature; the second, plastic, is associated with change of the material structure and the temperature increase; the third stage, related to the specimen rupture and damage mechanisms, is accompanied by the significant increase in temperature.

Keywords:
shape memory polymer, tension, thermomechanical coupling, temperature change, infrared camera

11p.
8.Staszczak M., Pieczyska E.A., Maj M., Urbański L., Odriozola I., Martin R., Thermomechanical Properties of Vulcanized Rubber investigated by Testing Machine and Infrared Camera, Measurement Automation Monitoring, ISSN: 0032-4140, Vol.61, No.6, pp.206-209, 2015
Staszczak M., Pieczyska E.A., Maj M., Urbański L., Odriozola I., Martin R., Thermomechanical Properties of Vulcanized Rubber investigated by Testing Machine and Infrared Camera, Measurement Automation Monitoring, ISSN: 0032-4140, Vol.61, No.6, pp.206-209, 2015

Abstract:
Experimental results of effects of thermomechanical couplings occurring both in natural vulcanized rubber and rubber with self-healing polyurethane subjected to tension at different strain rates are presented. Mechanical characteristics were recorded by testing machine, while the sample temperature changes accompanying the deformation process was measured by infrared camera. The goal was to investigate influence of self-healing polyurethane on the rubber mechanical and thermomechanical properties. It was found that the introduction of the self-healing polyurethane ensures the higher elasticity and the lower tensile strength of the rubber. It was also confirmed that the material is very sensitive to the strain rate; the higher the strain rate, the higher the values of the stress and temperature increases have been obtained.

Keywords:
vulcanized rubber, self-healing polyurethane, tension test, thermomechanical couplings, temperature changes, infrared camera

11p.
9.Pieczyska E.A., Maj M., Kowalczyk-Gajewska K., Staszczak M., Urbański L., Tobushi H., Hayashi S., Cristea M., Mechanical and Infrared Thermography Analysis of Shape Memory Polyurethane, Journal of Materials Engineering and Performance, ISSN: 1059-9495, DOI: 10.1007/s11665-014-0963-2, Vol.23, No.7, pp.2553-2560, 2014
Pieczyska E.A., Maj M., Kowalczyk-Gajewska K., Staszczak M., Urbański L., Tobushi H., Hayashi S., Cristea M., Mechanical and Infrared Thermography Analysis of Shape Memory Polyurethane, Journal of Materials Engineering and Performance, ISSN: 1059-9495, DOI: 10.1007/s11665-014-0963-2, Vol.23, No.7, pp.2553-2560, 2014

Abstract:
Multifunctional new material—polyurethane shape memory polymer (PU-SMP)—was subjected to tension carried out at room temperature at various strain rates. The influence of effects of thermomechanical couplings on the SMP mechanical properties was studied, based on the sample temperature changes, measured by a fast and sensitive infrared camera. It was found that the polymer deformation process strongly depends on the strain rate applied. The initial reversible strain is accompanied by a small drop in temperature, called thermoelastic effect. Its maximal value is related to the SMP yield point and increases upon increase of the strain rate. At higher strains, the stress and temperature significantly increase, caused by reorientation of the polymer molecular chains, followed by the stress drop and its subsequent increase accompanying the sample rupture. The higher strain rate, the higher stress, and temperature changes were obtained, since the deformation process was more dynamic and has occurred in almost adiabatic conditions. The constitutive model of SMP valid in finite strain regime was developed. In the proposed approach, SMP is described as a two-phase material composed of hyperelastic rubbery phase and elastic-viscoplastic glassy phase, while the volume content of phases is specified by the current temperature.

Keywords:
constitutive model, dynamic mechanical analysis, shape memory polyurethane, strain rate, temperature change, thermomechanical couplings

20p.
10.Pieczyska E.A., Kowalczyk-Gajewska K., Maj M., Staszczak M., Tobushi H., Thermomechanical investigation of TiNi shape memory alloy and PU shape memory polymer subjected to cyclic loading, Procedia Engineering, ISSN: 1877-7058, DOI: 10.1016/j.proeng.2014.06.264, Vol.74, pp.287-292, 2014
Pieczyska E.A., Kowalczyk-Gajewska K., Maj M., Staszczak M., Tobushi H., Thermomechanical investigation of TiNi shape memory alloy and PU shape memory polymer subjected to cyclic loading, Procedia Engineering, ISSN: 1877-7058, DOI: 10.1016/j.proeng.2014.06.264, Vol.74, pp.287-292, 2014

Abstract:
In applications to sensors, actuators, guide wires, special grips for handicapped people, a shape memory alloy (SMA) or shape memory polymer (SMP) are used as working elements that perform cyclic motions. In order to evaluate the reliability of the shape memory materials (SMM), cycling and fatigue deformation properties are investigated. Since the SMM are very sensitive to temperature, not only mechanical properties but also their related temperature changes accompanying the deformation process should be taken into account. The presented paper embraces experimental investigation of effects of thermomechanical couplings occurring in shape memory alloy and shape memory polymer subjected to various kinds of cycling loading. The deformation was carried out on MTS 858 Testing machine. The strain was measured by a mechanical extensometer, so the stress-strain characteristics were elaborated with high accuracy. Furthermore, a fast and sensitive FLIR Co Phoenix infrared (IR) measurement system was used in order to record infrared radiation from the sample surface. It enables obtaining temperature distribution of the sample as a function of the deformation parameters. For each strain cycle, an increase in temperature during the loading and the temperature decrease during the unloading processes was observed. It was found that the temperature increment recorded during the cyclic deformation depends on the strain rate, the kind of the material and the test conditions. The higher the strain rate the higher the stress and temperature changes were obtained, since the deformation process was more dynamic and has occurred in almost adiabatic conditions. It was shown that various deformation mechanisms are active during various loading stages.

Keywords:
shape memory alloy, shape memory polymer, cyclic deformation, thermomechanical coupling, infrared camera

11.Staszczak M., Pieczyska E.A., Maj M., Urbański L., Tobushi H., Hayashi S., Właściwości mechaniczne oraz zmiany temperatury polimeru z pamięcią kształtu w procesie rozciągania, POMIARY AUTOMATYKA KONTROLA, ISSN: 0032-4140, Vol.59, No.9, pp.1002-1005, 2013
Staszczak M., Pieczyska E.A., Maj M., Urbański L., Tobushi H., Hayashi S., Właściwości mechaniczne oraz zmiany temperatury polimeru z pamięcią kształtu w procesie rozciągania, POMIARY AUTOMATYKA KONTROLA, ISSN: 0032-4140, Vol.59, No.9, pp.1002-1005, 2013

Abstract:
This paper presents experimental evaluation of a new polyurethane shape memory polymer (PU-SMP) produced by SMP Technologies Inc. It discusses mechanical characteristics and temperature changes of the SMP specimens subjected to tension test performed at room temperature with various strain rates. Basing on the mechanical data and the relevant temperature changes, we have studied the thermomechanical properties of the PU-SMP and influence of the strain rate on the strain localization behavior. Finally, we have identified the material parameters for the one-dimensional rheological model of the SMP.

Keywords:
shape memory polyurethane, tension test, dynamic mechanical analysis, infrared camera, temperature change, thermomechanical properties, rheological model

7p.
12.Oliferuk W., Maj M., Litwinko R., Urbański L., Thermomechanical coupling in the elastic regime and elasto-plastic transition during tension of austenitic steel, titanium and aluminium alloy at strain rates from 10-4 to 10-1 s-1, EUROPEAN JOURNAL OF MECHANICS A-SOLIDS, ISSN: 0997-7538, DOI: 10.1016/j.euromechsol.2011.08.007, Vol.35, pp.111-118, 2012
Oliferuk W., Maj M., Litwinko R., Urbański L., Thermomechanical coupling in the elastic regime and elasto-plastic transition during tension of austenitic steel, titanium and aluminium alloy at strain rates from 10-4 to 10-1 s-1, EUROPEAN JOURNAL OF MECHANICS A-SOLIDS, ISSN: 0997-7538, DOI: 10.1016/j.euromechsol.2011.08.007, Vol.35, pp.111-118, 2012

Abstract:
The temperature variation phenomenon during uniaxial deformation of materials with positive coefficient of linear thermal expansion is studied. The formula for a change in the specimen temperature during non-adiabatic tensile deformation is briefly derived. Thermomechanical behaviour of austenitic stainless steel, titanium and aluminium alloy during initial stage of tension at strain rates from 10−4 to 10−1 s−1 has been investigated. It was confirmed, that with increasing stress the temperature of each tested specimen first decreases linearly, reaches a minimum and then starts to rise. The decrease in the specimen temperature corresponds to elastic deformation whereas the temperature rise is related to the plastic one. Thus, the change in the specimen temperature can be used for study of elasto-plastic transition. From the viewpoint of strict theoretical analysis, the yield point will be defined as the stress corresponding to the lowest temperature, if tensile deformation process is adiabatic. The processes of deformation considered in this work are not adiabatic; there is a heat exchange between the specimen and the surroundings. The influence of this fact on the change in the specimen temperature vs. stress is discussed. The problem of yield point as the value of stress corresponding to minimum temperature of the specimen is considered. The influence of the strain rate on the yield point for tested materials is studied. Comparing of the obtained results with theoretical model, the limit above which the deformation process can be treated as the adiabatic one was determined. The values of the yield points determined on the basis of the thermoelastic effect were compared with the stress corresponding to the 0.2% of plastic strain.

Keywords:
Thermoelastic effect, Yield point, Non-adiabatic deformation

30p.
13.Wysocka-Fotek O., Oliferuk W., Maj M., Reconstruction of size and depth of simulated defects in austenitic steel plate using pulsed infrared thermography, INFRARED PHYSICS AND TECHNOLOGY, ISSN: 1350-4495, DOI: 10.1016/j.infrared.2012.02.004, Vol.55, pp.363-367, 2012
Wysocka-Fotek O., Oliferuk W., Maj M., Reconstruction of size and depth of simulated defects in austenitic steel plate using pulsed infrared thermography, INFRARED PHYSICS AND TECHNOLOGY, ISSN: 1350-4495, DOI: 10.1016/j.infrared.2012.02.004, Vol.55, pp.363-367, 2012

Abstract:
In this paper the size and depth (distance from the tested surface) of defects in austenitic steel were estimated using pulse infrared thermography. The thermal contrast calculated from the surface distribution of the temperature is dependent on both these parameters. Thus, two independent experimental methods of defect size and depth determination were proposed. The defect size was estimated on the basis of surface distribution of the time derivative of the temperature, whereas the defect depth was assessed from the dependence of surface thermal contrast vs. cooling time.

Keywords:
pulsed IR thermography, temperature time derivative, defect size, thermal contrast, defect depth

25p.
14.Maj M., Oliferuk W., Analysis of Plastic Strain Localization on The Basis of Strain and Temperature Fields, ARCHIVES OF METALLURGY AND MATERIALS, ISSN: 1733-3490, DOI: 10.2478/v10172-012-0124-2, Vol.57, No.4, pp.1111-1116, 2012
Maj M., Oliferuk W., Analysis of Plastic Strain Localization on The Basis of Strain and Temperature Fields, ARCHIVES OF METALLURGY AND MATERIALS, ISSN: 1733-3490, DOI: 10.2478/v10172-012-0124-2, Vol.57, No.4, pp.1111-1116, 2012

Abstract:
In the present paper the onset of plastic strain localization was determined using two independent methods based on strain and temperature field analysis. The strain field was obtained from markers displacement recorded using visible light camera. In the same time, on the other side of the specimen, the temperature field was determined by means of infrared camera. The objective of this work was to specify the conditions when the non-uniform temperature distribution can be properly used as the indicator of plastic strain localization. In order to attain the objective an analysis of strain and temperature fields for different deformation rates were performed. It has been shown, that for given experimental conditions, the displacement rate 2000 mm/min is a threshold, above which the non-uniform temperature distribution can be used as the indicator of plastic strain localization.

Keywords:
plastic strain localization, strain field, temperature field, infrared thermography, heat transfer

20p.
15.Zimnoch M., Oliferuk W., Maj M., Estimation of Defect Depth in Steel Plate Using Lock-in IR Thermography, ACTA MECHANICA ET AUTOMATICA, ISSN: 1898-4088, Vol.4, No.4, pp.6-9, 2010
Zimnoch M., Oliferuk W., Maj M., Estimation of Defect Depth in Steel Plate Using Lock-in IR Thermography, ACTA MECHANICA ET AUTOMATICA, ISSN: 1898-4088, Vol.4, No.4, pp.6-9, 2010

Abstract:
The paper deals with the application of lock-in active infrared thermography as one of the non-contact and non-destructive techniques used for estimating defect depth. Preliminary research was done by testing a specimen made of austenitic steel plate with artificially created defects, i.e. flat-bottom holes. The obtained dependence between defect depth and phase shift was presented for different frequencies of “thermal waves” generated inside the sample. The experiment was carried out to determine the application of the lock-in thermography approach in testing materials with a high thermal diffusivity.

Keywords:
non-destructive testing, lock-in thermography, defect depth, phase shift, thermal diffusivity

6p.
16.Oliferuk W., Maj M., Stress-strain curve and stored energy during uniaxial deformation of polycrystals, EUROPEAN JOURNAL OF MECHANICS A-SOLIDS, ISSN: 0997-7538, DOI: 10.1016/j.euromechsol.2008.06.003, Vol.28, No.2, pp.266-272, 2009
Oliferuk W., Maj M., Stress-strain curve and stored energy during uniaxial deformation of polycrystals, EUROPEAN JOURNAL OF MECHANICS A-SOLIDS, ISSN: 0997-7538, DOI: 10.1016/j.euromechsol.2008.06.003, Vol.28, No.2, pp.266-272, 2009

Abstract:
The subject of this paper is an attempt to obtain information about the energy stored during plastic deformation from experimentally measured stress–strain curve. Theoretical analysis of the stress–strain curve for elastic-perfectly plastic polycrystalline material has shown that only the part of stored energy can be calculated from the stress–strain curve. This part is the energy stored during non-homogeneous plastic deformation. The results of such calculation have been compared with the total stored energy determined experimentally. It has been shown that part of total stored energy related to non-homogeneous plastic deformation of investigated materials is much lower than that corresponding to homogeneous one.

Keywords:
stored energy, non-homogeneous plastic deformation, geometrically-necessary dislocations

32p.
17.Wysocka-Fotek O., Oliferuk W., Maj M., Use of pulse IR thermography for detection and quantitative description of subsurface defects in austenitic steel, RUDY I METALE NIEŻELAZNE, ISSN: 0035-9696, Vol.54, No.11, pp.684-687, 2009
Wysocka-Fotek O., Oliferuk W., Maj M., Use of pulse IR thermography for detection and quantitative description of subsurface defects in austenitic steel, RUDY I METALE NIEŻELAZNE, ISSN: 0035-9696, Vol.54, No.11, pp.684-687, 2009

Abstract:
Pulsed IR thermography is a non-destructive testing method that allows detection of subsurface defects in material. In this method the surface of the tested specimen is stimulated by heat pulse and its self-cooling process is analyzed. The temperature decrease rate is different for surface over defect with comparison to that over the sound material. It is caused by difference between values of heat diffusivity of defected zone and sound one. The purpose of this work is to determine the size and depth of the defects in austenitic steel on the basis of thermal contrast analysis. Because the thermal contrast is dependent on both these parameters, two independent experimental methods of defect size and depth determination were proposed.

Keywords:
pulsed thermography, thermal contrast, defect characterization

9p.
18.Oliferuk W., Maj M., Components of energy storage rate during plastic deformation and their identification, RUDY I METALE NIEŻELAZNE, ISSN: 0035-9696, Vol.54, No.11, pp.732-735, 2009
Oliferuk W., Maj M., Components of energy storage rate during plastic deformation and their identification, RUDY I METALE NIEŻELAZNE, ISSN: 0035-9696, Vol.54, No.11, pp.732-735, 2009

Abstract:
The subject of the present paper is decomposition of energy storage rate into terms related to different mode of deformation. The stored energy is the change in internal energy due to plastic deformation determined after specimen unloading. Hence, this energy describes the state of the cold-worked material. Whereas, the ratio of the stored energy increament to the appropriate increament of plastic work is the measure of energy conversion process. This ratio is called the energy storage rate. Experimental results show that the energy storage rate is dependent on plastic strain. This dependence is influenced by different microscopic deformation mechanisms. It has been shown that the energy storage rate can be presented as a sum of particular components. Each of them is related to the separate internal microscopic mechanism. Two of the components are identified. One of them is the storage rate of statistically stored dislocation energy related to uniform deformation. Another one is connected with non-uniform deformation at the grain level. It is the storage rate of the long-range stresses energy and geometrically necessary dislocation energy.

Keywords:
stored energy, non-uniform plastic deformation, geometrically necessary dislocations

9p.
19.Oliferuk W., Maj M., Plastic instability criterion based on energy conversion, MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING, ISSN: 0921-5093, DOI: 10.1016/j.msea.2006.02.465, Vol.462, No.1-2, pp.363-366, 2007
Oliferuk W., Maj M., Plastic instability criterion based on energy conversion, MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING, ISSN: 0921-5093, DOI: 10.1016/j.msea.2006.02.465, Vol.462, No.1-2, pp.363-366, 2007

Abstract:
The energy conversion in the plastic deformation process is described by the energy storage rate, defined as the ratio of the stored energy increment to the plastic work increment. The experiment was performed on 304L and 316L stainless steels. It has been shown that during straining the material reaches the state at which the energy storage rate is zero and after that it is negative. This means that a part of energy stored during previous deformation begins to release. The point where the energy storage rate is zero turned out to be the point of Considere stability criterion. Therefore, the zero and negative values of the energy storage rate can be used as a plastic instability criterion on the macro-scale and the release of stored energy as an indicator to describe the progressive predominance of damage leading to the fracture of tested materials.

Keywords:
stored energy, plastic work, plastic instability criterion, non-homogeneous deformation, austenitic steel

27p.
20.Oliferuk W., Maj M., Energy storage rate and plastic instability, ARCHIVES OF METALLURGY AND MATERIALS, ISSN: 1733-3490, Vol.52, No.2, pp.250-256, 2007
Oliferuk W., Maj M., Energy storage rate and plastic instability, ARCHIVES OF METALLURGY AND MATERIALS, ISSN: 1733-3490, Vol.52, No.2, pp.250-256, 2007

Abstract:
The energy storage rate, defined as the ratio of the stored energy increment to the plastic work increment, versus strain was experimentally estimated in the range of homogeneous deformation as well as in the range of non-homogeneous one. The experiment were performed on 304L and 316L stainless steels. It has been shown, that during straining the material reaches the state at which the energy storage rate is zero and after that it is negative. This means that a part of energy stored during previous deformation begins to release.
It has been found that the point where the energy storage rate is zero turned out to be the point of Considere stability criterion. Therefore the release of stored energy could be used as an indicator to describe the progressive predominance of damage leading to the fracture of a material. This confirms Considere construction that specimen will undergo stable deformation up to the point on the stress-strain curve, for which the strain hardening rate is equal to the flow stress. Some attempts to explain the release of stored energy in terms of microstructure phenomena has been made.

Keywords:
energy storage rate, plastic work, non-homogeneous deformation, Considere stability criterion

20p.
21.Oliferuk W., Maj M., Identyfikacja składników energii zmagazynowanej podczas jednoosiowego rozciągania, RUDY I METALE NIEŻELAZNE, ISSN: 0035-9696, Vol.52, No.11, pp.695-702, 2007
Oliferuk W., Maj M., Identyfikacja składników energii zmagazynowanej podczas jednoosiowego rozciągania, RUDY I METALE NIEŻELAZNE, ISSN: 0035-9696, Vol.52, No.11, pp.695-702, 2007

Abstract:
Podjęto próbę wyznaczenia energii zmagazynowanej na podstawie zależności naprężenie-odkształcenie. Przeprowadzona analiza teoretyczna pokazała, że w ten sposób można wyznaczyć jedynie dolną granicę energii zmagazynowanej. Na podstawie uproszczonego modelu materiału polikrystalicznego, podjęto próbę identyfikacji składników energii zmagazynowanej. Wykazano, że dolną granicę tej energii można traktować jako energię zmagazynowaną na skutek deformacji mikroskopowo niejednorodnej. Wyniki analizy teoretycznej porównano z całkowitą energią zmagazynowaną wyznaczoną eksperymentalnie.

Keywords:
energia zmagazynowana, odkształcenie jednorodne i niejednorodne, rozkład gęstości dyslokacji

9p.
22.Oliferuk W., Beygelzimer Y., Maj M., Synkov S., Reshetov A., Pakieła Z., Zdolność magazynowania energii podczas rozciągania tytanu po wyciskaniu przez matrycę skrętną, Polska metalurgia w latach 2002-2006; Wydawnictwo Naukowe Akapit (Kraków), Świątkowski K. (Ed.), pp.495-500, 2006
Oliferuk W., Beygelzimer Y., Maj M., Synkov S., Reshetov A., Pakieła Z., Zdolność magazynowania energii podczas rozciągania tytanu po wyciskaniu przez matrycę skrętną, Polska metalurgia w latach 2002-2006; Wydawnictwo Naukowe Akapit (Kraków), Świątkowski K. (Ed.), pp.495-500, 2006

Abstract:
The presented work is devoted to experimental studies of the energy storage process in the tensile test of the ultrafine-grained (UFG) titanium in comparison with the coarse-grained one. The UFG titanium was obtained using severe plastic deformation method (SPD) called twist extrusion (TE) that is briefly presented.
The experiments were performed on three groups of titanium specimens. Two of them (T1 and T2) were cut from the materials obtained by TE method. The T1 titanium was processed by 4 passes through the left twist die, whereas for the T2 titanium the twist direction was changed after the first pass. The last group (T0) was prepared from the annealed sheet of coarse-grained titanium. It was noticed that mechanical properties of the material underwent TE differs considerably from properties of te coarsed-grained one. It was observed that yield point obtained for specimens after TE is about 30% higher then that for coarsed-grained material. However, the elongation decrease was observed for both groups of specimens after TE (T1~60%, T2~25%) with respect to T0 ones.
The energy storage investigations show the differences in the energy storage rate for T1 and T2 specimens. In the case of T1 specimens the energy storage rate decreases rapidly with strain whereas for T2 specimens (where twist direction was changed) the energy storage rate remains constant at the homogeneous deformation range. The experimental results show that the change of the twist direction during TE may improve the mechanical properties of the material. The constant rate of energy storage in specimens after twist direction change may be macroscopic manifestation of homogeneous and more stable structure of the material.

Keywords:
energy storage rate, ultrafine-grained titanium, severe plastic deformation, twist extrusion


Lista rozdziałów w ostatnich monografiach
1.
449
Pieczyska E.A., Maj M., Furuta T., Kuramoto S., Advances in Mechanics: Theoretical, Computational and Interdisciplinary Issues, rozdział: Gum Metal - unique properties and results of initial investigation of a new titanium alloy - extended paper, CRC Press/Balkema, Taylor & Francis Group, M. Kleiber et al. (Eds.), pp.469-472, 2016

Prace konferencyjne
1.Pieczyska E.A., Staszczak M., Maj M., Kowalczyk-Gajewska K., Cristea M., Tobushi H., Hayashi S., Thermomechanical analysis of shape memory polyurethane PU-SMP, 6th International Conference on Mechanics and Materials in Design, 2015-07-26/07-30, Ponta Delgada (PT), pp.783-786, 2015
Pieczyska E.A., Staszczak M., Maj M., Kowalczyk-Gajewska K., Cristea M., Tobushi H., Hayashi S., Thermomechanical analysis of shape memory polyurethane PU-SMP, 6th International Conference on Mechanics and Materials in Design, 2015-07-26/07-30, Ponta Delgada (PT), pp.783-786, 2015

Abstract:
Experimental results of effects of thermomechanical couplings occurring in polyurethane shape memory polymer (PU-SMP) during tension at different strain rates are presented. Stress-strain curves were recorded by MTS 858 testing machine. The temperature changes were estimated by using a fast and sensitive infrared camera (Phoenix FLIR IR System). The stress and temperature vs. strain characteristics obtained during the tension enable to investigate the SMP deformation process and distinguish 3 different stages: the first, accompanied by a drop in temperature called thermoelastic effect, related to a limit of the material reversible deformation, the second plastic stage, associated with change of the material structure and significant increase in temperature, and the third - related to the mechanisms of damage - a breaking of the polymer chains, leading to the specimen rupture.

Keywords:
shape memory polymer, thermomechanical coupling, tension, infrared camera

2.Oliferuk W., Maj M., Distributions of energy storage rate and microstructural evolution in the area of plastic strain localization during uniaxial tension of austenitic steel, IOP Conference Series: Materials Science and Engineering, ISSN: 1757-899X, DOI: 10.1088/1757-899X/89/1/012040, Vol.89, pp.012040-1-8, 2015
Oliferuk W., Maj M., Distributions of energy storage rate and microstructural evolution in the area of plastic strain localization during uniaxial tension of austenitic steel, IOP Conference Series: Materials Science and Engineering, ISSN: 1757-899X, DOI: 10.1088/1757-899X/89/1/012040, Vol.89, pp.012040-1-8, 2015

Abstract:
The presented work is devoted to an experimental determination of the energy storage rate in the area of strain localization. The experimental procedure involves two complementary techniques: i.e. infrared thermography (IRT) and visible light imaging. The results of experiments have shown that during the evolution of plastic strain localization the energy storage rate in some areas of the deformed specimen drops to zero. To interpret the decrease of the energy storage rate in terms of micro-mechanisms, microstructural observations using Transmission Electron Microscopy (TEM) and Electron Back Scattered Diffraction (EBSC) were performed. On the basis of microstructural studies it is believed that a 0 value of energy storage rate corresponds to the state in which only two dominant components of the texture appear, creating conditions for crystallographic shear banding.

Keywords:
energy storage rate, strain localization, infrared thermography, microstructure evolution, crystallographic texture

15p.
3.Oliferuk W., Maj M., Zembrzycki K., Distribution of energy storage rate in area of strain localization during tension of austenitic steel, IOP Conference Series: Materials Science and Engineering, ISSN: 1757-899X, DOI: 10.1088/1757-899X/71/1/012055, Vol.71, pp.012055-1-8, 2015
Oliferuk W., Maj M., Zembrzycki K., Distribution of energy storage rate in area of strain localization during tension of austenitic steel, IOP Conference Series: Materials Science and Engineering, ISSN: 1757-899X, DOI: 10.1088/1757-899X/71/1/012055, Vol.71, pp.012055-1-8, 2015

Abstract:
The present work is devoted to experimental determination of the energy storage rate in the area of strain localization. The experimental procedure involves two complementary techniques: i.e. infrared thermography (IRT) and visible light imaging. The results of experiments have shown that during the evolution of plastic strain localization the energy storage rate in some areas of the deformed specimen drops to zero. To interpret the decrease of the energy storage rate in terms of micro-mechanisms, microstructural observations using electron back scattered diffraction (EBSC) were performed.

Keywords:
energy balance, strain localization, infrared thermography, texture evolution

15p.
4.Pieczyska E.A., Staszczak M., Maj M., Tobushi H., Hayashi S., Thermal effects accompanying tensile deformation of shape memory polymer PU-SMP, 11th Conference on Thermography and Thermometry in Infrared, 2015-09-22/09-24, Ustroń (PL), pp.60-65, 2015
Pieczyska E.A., Staszczak M., Maj M., Tobushi H., Hayashi S., Thermal effects accompanying tensile deformation of shape memory polymer PU-SMP, 11th Conference on Thermography and Thermometry in Infrared, 2015-09-22/09-24, Ustroń (PL), pp.60-65, 2015

Abstract:
In the paper experimental results of the effects of thermomechanical couplings occurring in polyurethane shape memory polymer (PU-SMP), produced by SMP Techno Tokyo, subjected to tension with various strain rates are presented. Stress-strain curves were recorded by MTS 858 testing machine with a high accuracy, while using a fast and sensitive infrared camera (Phoenix FLIR IR System) enables to obtain the temperature distribution on the specimen surface, estimate the average temperature and investigate effects of the strain localization during the deformation process. The higher the strain rate the higher the changes in the stress and in temperature are observed, since the deformation mechanisms occur in more dynamic manner and the loading process is closer to adiabatic conditions.

Keywords:
shape memory polymer, thermomechanical couplings, tension, infrared camera, thermoelastic effect, yield point, temperature distribution, strain localization, strain rate, adiabatic conditions

5.Staszczak M., Pieczyska E.A., Maj M., Urbański L., Odriozola I., Martin R., Właściwości termomechaniczne gumy wulkanizowanej badane za pomocą maszyny wytrzymałościowej oraz kamery termowizyjnej, 11th Conference on Thermography and Thermometry in Infrared, 2015-09-22/09-24, Ustroń (PL), pp.66-67, 2015
Staszczak M., Pieczyska E.A., Maj M., Urbański L., Odriozola I., Martin R., Właściwości termomechaniczne gumy wulkanizowanej badane za pomocą maszyny wytrzymałościowej oraz kamery termowizyjnej, 11th Conference on Thermography and Thermometry in Infrared, 2015-09-22/09-24, Ustroń (PL), pp.66-67, 2015

Abstract:
Praca przedstawia wyniki doświadczalnych badań efektów sprzężeń termomechanicznych w naturalnej, wulkanizowanej gumie z różną zawartością poliuretanu o właściwościach samo-naprawiania, tzw. „self-healing‖ podczas obciążania z różnymi prędkościami deformacji. Próbki rozciągano na maszynie wytrzymałościowej wysokiej klasy, co pozwoliło otrzymać charakterystyki mechaniczne z wysoką dokładnością, a szybka i czuła kamera termowizyjna pozwoliła otrzymać w sposób bezstykowy zmiany temperatury próbek związane z ich odkształcaniem. Stwierdzono, że im więcej dodatku poliuretanu, tym wyższa sprężystość gumy oraz niższa jej wytrzymałość. Ponadto, otrzymane wyniki potwierdziły wysoką wrażliwość materiału na prędkość deformacji: im wyższa prędkość, tym wyższe wartości naprężenia oraz zmian temperatury.

Keywords:
efekty sprzężeń termomechanicznych, wulkanizowana guma, poliuretan self-healing, prędkość deformacji, maszyna wytrzymałościowa, kamera termowizyjna

6.Staszczak M., Pieczyska E.A., Maj M., Kowalczyk-Gajewska K., Kukla D., Tobushi H., Hayashi S., Infrared thermography analysis of thermomechanical shape memory polymer behavior – initial loading stage, AITA, 13th International Workshop on Advanced Infrared Technology and Applications, 2015-09-29/10-02, Pisa (IT), pp.115-118, 2015
Staszczak M., Pieczyska E.A., Maj M., Kowalczyk-Gajewska K., Kukla D., Tobushi H., Hayashi S., Infrared thermography analysis of thermomechanical shape memory polymer behavior – initial loading stage, AITA, 13th International Workshop on Advanced Infrared Technology and Applications, 2015-09-29/10-02, Pisa (IT), pp.115-118, 2015

Abstract:
Experimental results of effects of thermomechanical couplings occurring in polyurethane shape memory polymer (PU-SMP) subjected to cyclic loading at various strain rates are presented. Stress-strain characteristics were recorded by the testing machine, whereas the specimen temperature changes were measured by a fast and sensitive infrared camera. The influence of strain rate on the polymer thermomechanical behaviour was studied. It was found that the SMP is very sensitive to the strain rate. The higher the strain rate, the higher the values of the stress and temperature changes were obtained. In the initial stage of deformation a drop in temperature called thermoelastic effect, determining a limit of the material reversible deformation, was investigated.

Keywords:
thermomechanical couplings, polyurethane shape memory polymer, cyclic loading, various strain rates, sensitive infrared camera, thermoelastic effect, thermoelastic effect, reversible deformation

7.Pieczyska E., Maj M., Kowalczyk-Gajewska K., Staszczak M., Tobushi H., Hayashi S., Thermomechanical properties of shape memory alloys and polymers studied by advanced infrared techniques, PACAM, 14th Pan-American Congress of Applied Mechanics, 2014-03-24/03-28, Santiago (CL), pp.1-6, 2014
Pieczyska E., Maj M., Kowalczyk-Gajewska K., Staszczak M., Tobushi H., Hayashi S., Thermomechanical properties of shape memory alloys and polymers studied by advanced infrared techniques, PACAM, 14th Pan-American Congress of Applied Mechanics, 2014-03-24/03-28, Santiago (CL), pp.1-6, 2014

Abstract:
The paper presents experimental evaluation and modelling of effects of thermomechanical couplings in shape memory alloy (SMA) and shape memory polymer (SMP). TiNi SMA and polyurethane PU-SMP are subjected to tension on MTS Testing machine. Fast infrared camera (IR) Phoenix FLIR System enable obtaining temperature distribution and average temperature changes of the specimens during the deformation process. Mechanical and infrared characteristics recorded during the SMA loading show that after initial, macroscopically homogeneous deformation a localized transformation develops, accompanied by significant temperature changes. Inclined bands of higher temperature accompanying exothermic forward transformation are recorded during the loading, whereas bands of lower temperature related to endothermic reverse transformation are observed during the unloading process. The infrared imaging and average temperature of the SMA sample compared to their mechanical characteristics allow to investigate the current stage of the stress-induced transformation process. A decrease of the specimen temperature reveals the saturation stage of the transformation. Both mechanical and thermal effects significantly depend on the strain rate; the higher the strain rate, the higher the temperature and stress are obtained. Similar experimental methodology is applied to investigate effects of thermomechanical couplings in shape memory polyurethane subjected to tension at various strain rates. Constitutive model valid in finite strain regime is proposed, where the SMP is described as a two-phase material composed of hyperelastic rubbery phase and elastic-viscoplastic glassy phase, while the volume content of phases is specified by the current temperature. Experimental results and modelling show that the SMP deformation process strongly depends on the strain rate, much stronger than for metals and alloys. At higher strain rate higher stress and temperature changes are obtained, since the deformation process is more dynamic and occurs in almost adiabatic conditions. It is shown that during the SMP loading process various deformation mechanisms are active at various strain rates.

Keywords:
shape memory alloy, transformation bands, infrared camera, constitutive model, shape memory polymers, elastic modulus, yield stress, glass transition temperature, shape fixity, shape recovery

8.Staszczak M., Pieczyska E.A., Maj M., Kowalczyk-Gajewska K., Cristea M., Tobushi H., Hayashi S., Mechanical and infrared thermography analysis of shape memory polymer - focus on thermoelastic effect, QIRT 2014, 12th International Conference on Quantitative Infrared Thermography, 2014-07-07/07-11, Bordeaux (FR), pp.183-1-9, 2014
Staszczak M., Pieczyska E.A., Maj M., Kowalczyk-Gajewska K., Cristea M., Tobushi H., Hayashi S., Mechanical and infrared thermography analysis of shape memory polymer - focus on thermoelastic effect, QIRT 2014, 12th International Conference on Quantitative Infrared Thermography, 2014-07-07/07-11, Bordeaux (FR), pp.183-1-9, 2014

Abstract:
Experimental results of effects of thermomechanical couplings occurring in polyurethane shape memory polymer (PU-SMP) subjected to cyclic loading at , are presented. Stress-strain characteristics were recorded by the testing machine, whereas the specimen temperature changes were measured by a fast and sensitive infrared camera. The influence of strain rate on the polymer thermomechanical behaviour is studied. It was found that PU-SMP is very sensitive to the strain rate. The higher the strain rate, the higher the values of stress and temperature changes were obtained. In the initial stage of deformation a drop in temperature called thermoelastic effect was recorded determining a limit of the material reversible deformation.

Keywords:
thermomechanical couplings, polyurethane shape memory polymer, cyclic loading, different strain rates, infrared camera, thermoelastic effect

9.Oliferuk W., Maj M., Distribution of energy storage rate in area of plastic strain localization during tension, 3rd International Conference Topical Problems of Continuum Mechanics, 2012-10-08/08-12, Tsakhkadzor (AM), No.1, pp.282-286, 2012
Oliferuk W., Maj M., Distribution of energy storage rate in area of plastic strain localization during tension, 3rd International Conference Topical Problems of Continuum Mechanics, 2012-10-08/08-12, Tsakhkadzor (AM), No.1, pp.282-286, 2012

Abstract:
The presented work is devoted to the new method of energy storage rate detrmination that allows to obtain distribution of this quantity on the surface of deformed specimen. The method is based on the experimental procedure for simultaneous measurements of themperature and displacement distributions on the surface of tested specimen during tensile deformation. This procedure involves two complementary imaging techniques: CCD technique and infrared thermography (IRT). It has been shown experimentally that during evolution of plastic strain localization the energy storage in some zones of deformed specimen dropes to zero even to negative values. To interpret this results in terms of micromechanisms, microstructural obserwations using electron back scattered diffraction (EBSD) and transmission electron microscopy (TEM) were performed on specimens in different states of deformation.

Keywords:
energy storage rate, infrared thermography, plastic strain localization, texture evolution

10.Maj M., Oliferuk W., Pre-strain direction effect on microstructure evolution and energy storage process during uniaxial tension of austenitic steel, 15th International Conference on the Strength of Materials, 2009-08-16/08-21, Dresden (DE), DOI: 10.1088/1742-6596/240/1/012143, Vol.240, pp.012143-1-4, 2010
Maj M., Oliferuk W., Pre-strain direction effect on microstructure evolution and energy storage process during uniaxial tension of austenitic steel, 15th International Conference on the Strength of Materials, 2009-08-16/08-21, Dresden (DE), DOI: 10.1088/1742-6596/240/1/012143, Vol.240, pp.012143-1-4, 2010

Abstract:
In the present paper the influence of pre-strain direction on energy balance during deformation of austenitic steel was investigated and the analysis of microscopic phenomena responsible for this influence was performed. The specimens with different pre-strain directions were prepared and the ratio of the stored energy increment to plastic work increment, called energy storage rate, as a function of plastic strain was experimentally determined. At the initial stage of plastic deformation of annealed materials this quantity vs. plastic strain has a maximum. It has been shown that for specimens strained in the same direction as pre-strain the energy storage rate decreases monotonically with deformation while for specimens where strain path was changed, the maximum of the energy storage rate is observed (as in case of annealed material). The study of slip and microstructure evolution at meso- and micro-scales have shown that the change in pre-strain direction leads to the redistribution of internal stresses generated by incompatible slip in neighbouring grains of different orientation. Just after change in strain direction the accommodation of these stresses takes place not only by generation of geometrically necessary dislocations but also by micro-shear banding.

Keywords:
energy storage rate, pre-strain direction, slip evolution, long-range internal stresses, geometrically necessary dislocations, micro-shear bands

11.Oliferuk W., Maj M., Identification of energy storage rate components. Theoretical and experimental approach, 15th International Conference on the Strength of Materials, 2009-08-16/08-21, Dresden (DE), DOI: 10.1088/1742-6596/240/1/012144, Vol.240, pp.012144-1-4, 2010
Oliferuk W., Maj M., Identification of energy storage rate components. Theoretical and experimental approach, 15th International Conference on the Strength of Materials, 2009-08-16/08-21, Dresden (DE), DOI: 10.1088/1742-6596/240/1/012144, Vol.240, pp.012144-1-4, 2010

Abstract:
The subject of the present paper is decomposition of energy storage rate into terms related to different mode of deformation. The stored energy is the change in internal energy due to plastic deformation after specimen unloading. Hence, this energy describes the state of the cold-worked material. Whereas, the ratio of the stored energy increment to the appropriate increment of plastic work is the measure of energy conversion process. This ratio is called the energy storage rate. Experimental results show that the energy storage rate is dependent on plastic strain. This dependence is influenced by different microscopic deformation mechanisms.

It has been shown that the energy storage rate can be presented as a sum of particular components. Each of them is related to the separate internal microscopic mechanism. Two of the components are identified. One of them is the storage rate of statistically stored dislocation energy related to uniform deformation. Another one is connected with non-uniform deformation at the grain level. It is the storage rate of the long range stresses energy and geometrically necessary dislocation energy. The maximum of energy storage rate, that appeared at initial stage of plastic deformation is discussed in terms of internal micro-stresses.

Keywords:
stored energy, deformation mechanisms, statistically stored dislocations, geometrically stored dislocations, long-range internal stresses


Abstrakty konferencyjne
1.Pieczyska E., Golasiński K., Staszczak M., Maj M., Furuta T., Kuramoto S., High elasto-plastic properties of new titanium alloy gum metal in wide spectra of the strain rates, 17th International Conference on Experimental Mechanics, 2016-07-03/07-07, Rhodes (GR), No.388, pp.1-2, 2016
Pieczyska E., Golasiński K., Staszczak M., Maj M., Furuta T., Kuramoto S., High elasto-plastic properties of new titanium alloy gum metal in wide spectra of the strain rates, 17th International Conference on Experimental Mechanics, 2016-07-03/07-07, Rhodes (GR), No.388, pp.1-2, 2016

Abstract:
Results of investigation of mechanical properties and the related temperature changes in a β-Ti alloy, Gum Metal, subjected to tension in a wide spectrum of the strain rates are presented. The stress-strain curves have been obtained by MTS testing machine while fast and sensitive infrared camera Phoenix Flir Co. allowed estimating temperature changes accompanying the specimen deformation process. The obtained mechanical curves confirm an ultra- low elastic modulus and high strength of Gum Metal. The yield point was estimated with high accuracy basing on the thermoelastic effect measured by the advanced infrared technique. Furthermore, it was observed that the stress-strain characteristics change from hardening to softening beyond the Yield point depending on the strain rate applied.

Keywords:
Gum metal, Titanium alloy, Superelastic nonlinear properties, strain rate

2.Pieczyska E.A., Golasiński K., Staszczak M., Maj M., Furuta T., Kuramoto S., Gum metal subjected to cyclic tension loading analysed by fast and sensitive infrared camera, ICMFM18, XVIII International Colloquium MECHANICAL FATIGUE OF METALS, 2016-09-05/09-07, Gijón (ES), pp.1, 2016
Pieczyska E.A., Golasiński K., Staszczak M., Maj M., Furuta T., Kuramoto S., Gum metal subjected to cyclic tension loading analysed by fast and sensitive infrared camera, ICMFM18, XVIII International Colloquium MECHANICAL FATIGUE OF METALS, 2016-09-05/09-07, Gijón (ES), pp.1, 2016

Abstract:
Gum Metal, a new multifunctional titanium alloy combining high elasticity of rubber and strength of metal, has been mechanically and thermomechanically tested. The subsequent tension deformation cycles have been conducted. At the strain rate of 10-2s-1 and step of 0.005 - 37 loading-unloading cycles until rupture were performed. Comparison of stress and temperature changes vs. strain for 2nd, 20th and 36th loading-unloading cycles is discussed.

Keywords:
Gum Metal, cyclic loading, infrared camera, thermomechanical coupling

3.Golasiński K., Pieczyska E., Maj M., Staszczak M., Takesue N., Investigation of Gum Metal under compressive cyclic loading, Plastmet 2016, Jubileuszowe X Seminarium Naukowe ZINTEGROWANE STUDIA PODSTAW DEFORMACJI PLASTYCZNEJ METALI , 2016-11-22/11-25, Łańcut (PL), pp.41-42, 2016
Golasiński K., Pieczyska E., Maj M., Staszczak M., Takesue N., Investigation of Gum Metal under compressive cyclic loading, Plastmet 2016, Jubileuszowe X Seminarium Naukowe ZINTEGROWANE STUDIA PODSTAW DEFORMACJI PLASTYCZNEJ METALI , 2016-11-22/11-25, Łańcut (PL), pp.41-42, 2016

Abstract:
Preliminary results of mechanical behavior of Gum Metal compressed along the swaging direction during cyclic loading were presented. The unique mechanical performance of Gum Metal - low Young’s Modulus and high strength were confirmed. During the cyclic loading the curves profiles change significantly with each cycle and reveal a clearly pronounced yield points for the 4th and further cycles. Compression tests along perpendicular direction to the swaging one will be considered for our future research.

Keywords:
Gum Metal, polycrystal, compression loading, cyclic loading, digital image correlation

4.Golasiński K., Pieczyska E., Staszczak M., Maj M., Furuta T., Kuramoto S., Infrared thermography applied for experimental investigation of thermomechanical couplings in Gum Metal, QIRT 2016, XIII International Quantitative InfraRed Thermography Conference, 2016-06-04/06-08, Gdańsk (PL), pp.318-319, 2016
Golasiński K., Pieczyska E., Staszczak M., Maj M., Furuta T., Kuramoto S., Infrared thermography applied for experimental investigation of thermomechanical couplings in Gum Metal, QIRT 2016, XIII International Quantitative InfraRed Thermography Conference, 2016-06-04/06-08, Gdańsk (PL), pp.318-319, 2016

Abstract:
Results of investigation of thermomechanical couplings in innovative β-Ti alloy (Gum Metal) subjected to tension are presented. The experimental set-up, consisting of testing machine and infrared camera, enabled to obtain stress-strain curves with high accuracy and correlate them to estimated temperature changes of the sample during the deformation process. Both ultra-low elastic modulus and high strength of Gum Metal were confirmed. The infrared measurements determined average and maximal temperature changes accompanying the alloy deformation process, allowed to estimate thermoelastic effect, which is related to the alloy yield point. The temperature distributions on the sample surface served to analyze localization effects leading to the sample necking and rupture.

Keywords:
Gum metal, nonlinear elasticity, thermomechanical couplings

5.Golasiński K., Pieczyska E., Staszczak M., Maj M., Furuta T., Kuramoto S., Thermomechanical behavior of gum metal under cyclic loading, SolMech 2016, 40th Solid Mechanics Conference, 2016-08-29/09-02, Warszawa (PL), No.P208, pp.1-2, 2016
Golasiński K., Pieczyska E., Staszczak M., Maj M., Furuta T., Kuramoto S., Thermomechanical behavior of gum metal under cyclic loading, SolMech 2016, 40th Solid Mechanics Conference, 2016-08-29/09-02, Warszawa (PL), No.P208, pp.1-2, 2016

Abstract:
This work presents thermomechanical characterization of a new multifunctional class of β-Ti alloy called Gum Metal subjected to cyclic tensile loading. Being developed in the Toyota Central R&D Laboratory (CRDL), Gum Metal has attracted remarkable attention due to its exceptional properties, i.e. low elastic modulus, high strength, nonlinear elastic deformation, excellent cold workability as well as Invar- and Elinvar-like behavior. Typical composition of Gum Metal is Ti-Nb-Ta-Zr-O, where oxygen content plays a key role. Its fabrication route consists of powder metallurgy forging method with subsequent cold working usually up to 90% in area reduction. The latter is critical for the unique mechanical performance but deformation mechanisms occurring in Gum Metal are unconventional and still unclear.

Keywords:
Gum metal, cyclic loading, titanium alloy, thermomechanical behavior

6.Pieczyska E., Maj M., Furuta T., Kuramoto S., Gum Metal – unique properties and results of initial investigation of the new titanium alloy, PCM-CMM 2015, 3rd Polish Congress of Mechanics and 21st Computer Methods in Mechanics, 2015-09-08/09-11, Gdańsk (PL), pp.145-146, 2015
Pieczyska E., Maj M., Furuta T., Kuramoto S., Gum Metal – unique properties and results of initial investigation of the new titanium alloy, PCM-CMM 2015, 3rd Polish Congress of Mechanics and 21st Computer Methods in Mechanics, 2015-09-08/09-11, Gdańsk (PL), pp.145-146, 2015

Abstract:
Initial results of effects of thermomechanical couplings in the β-Ti alloy, Gum Metal, subjected to tension are presented. An MTS testing machine allows obtaining stress-strain curves with high accuracy, while fast and sensitive infrared camera allows estimating temperature changes of the sample during the deformation process. The obtained mechanical characteristics confirm an ultra-low elastic modulus and high strength of the Gum Metal. The infrared measurements enable to indicate average or maximum temperature change accompanying the alloy deformation process, to estimate thermoelastic effect, related to the yield point in solids, whereas the temperature distribution on the sample surface enables to investigate localisation effects, leading to the sample necking and rupture.

Keywords:
Gum Metal, Titanium alloy, Elastic properties, Nonlinear elasticity, thermomechanical couplings, infrared camera

7.Staszczak M., Pieczyska E., Maj M., Kowalczyk-Gajewska K., Cristea M., Tobushi H., Hayashi S., Shape memory polymer – shape fixity and recovery in cyclic loading, PCM-CMM 2015, 3rd Polish Congress of Mechanics and 21st Computer Methods in Mechanics, 2015-09-08/09-11, Gdańsk (PL), pp.147-148, 2015
Staszczak M., Pieczyska E., Maj M., Kowalczyk-Gajewska K., Cristea M., Tobushi H., Hayashi S., Shape memory polymer – shape fixity and recovery in cyclic loading, PCM-CMM 2015, 3rd Polish Congress of Mechanics and 21st Computer Methods in Mechanics, 2015-09-08/09-11, Gdańsk (PL), pp.147-148, 2015

Abstract:
The paper concerns investigation of polyurethane shape memory polymer (SMP) properties. Shape fixity and shape recovery, important parameters for the SMP applications, were quantitatively estimated in thermomechanical cyclic loading; three subsequent thermomechanical loading cycles were performed. It was observed that the shape fixity is proper and does not depend on the cycle number. The obtained mean values of shape fixity parameters are 97-98 %. Although the shape recovery is poor (=83 %) in the first cycle of the thermomechanical loading, it is excellent in the subsequent cycles (=99-100 %). The evaluated parameters confirm good shape memory properties of the SMP.

Keywords:
Shape memory polyurethane, shape fixity, shape recovery, thermomechanical loading, cyclic loading

8.Kowalczyk-Gajewska K., Frydrych K., Maj M., Urbański L., Micromechanical modelling of magnesium alloy and its experimental verification, PCM-CMM 2015, 3rd Polish Congress of Mechanics and 21st Computer Methods in Mechanics, 2015-09-08/09-11, Gdańsk (PL), pp.677-678, 2015
Kowalczyk-Gajewska K., Frydrych K., Maj M., Urbański L., Micromechanical modelling of magnesium alloy and its experimental verification, PCM-CMM 2015, 3rd Polish Congress of Mechanics and 21st Computer Methods in Mechanics, 2015-09-08/09-11, Gdańsk (PL), pp.677-678, 2015

Abstract:
Micromechanical modelling of magnesium alloys is presented. The applied model combines the crystal plasticity framework accounting for twinning with the self-consistent grain-to-polycrystal scale transition scheme. The mechanical response of the material in the experiments involving the strain path changes is studied, together with the prediction of the accompanying texture evolution. It is demonstrated that the evolution of microstructure has an important impact on the overall material behaviour. The model predictions will be verified in experiments performed on the rolled sheets made of AZ31B alloy

Keywords:
micromechanics, crystal plasticity, twinning, texture evolution

9.Pieczyska E., Staszczak M., Maj M., Kowalczyk-Gajewska K., Tobushi H., Właściwości termomechaniczne i zastosowania polimerów z pamięcią kształtu, XI Konferencja Nowe Kierunki Rozwoju Mechaniki, 2015-03-18/03-20, Sarbinowo (PL), pp.75-76, 2015
Pieczyska E., Staszczak M., Maj M., Kowalczyk-Gajewska K., Tobushi H., Właściwości termomechaniczne i zastosowania polimerów z pamięcią kształtu, XI Konferencja Nowe Kierunki Rozwoju Mechaniki, 2015-03-18/03-20, Sarbinowo (PL), pp.75-76, 2015

Abstract:
Polimery z pamięcią kształtu, podobnie jak niektóre stopy metali, wykazują efekt pamięci kształtu. Wykorzystuje się w nich różnicę właściwości termomechanicznych poniżej i powyżej temperatury zeszklenia Tg, w której polimer radykalnie zmienia swe własności, m.in. wartość modułu sprężystości. Materiały te posiadają możliwość szybkiej zmiany właściwości fizycznych w zależności od temperatury. Stają się miękkie po podgrzaniu powyżej Tg i pozwalają się łatwo formować, a podczas schłodzenia poniżej tej temperatury odzyskują poprzednią sztywność. Nadal pamiętają swój oryginalny kształt i wracają do niego podczas ponownego podgrzania powyżej Tg. Umożliwia to ich różnorodne praktyczne zastosowania, m.in. w przemyśle medycznym i farmaceutycznym, tekstylnym, spożywczym, lotniczym i kosmicznym.

Keywords:
Polimery z pamięcią kształtu, temperatura zeszklenia, wartość modułu sprężystości, kamera termowizyjna

10.Pieczyska E.A., Maj M., Kowalczyk-Gajewska K., Staszczak M., Tobushi H., Hayashi S., Cristea M., Thermomechanical analysis of shape memory polymer under cyclic loading and relaxation conditions, ICEM-16, 16th International Conference on Experimental Mechanics, 2014-07-07/07-11, Cambridge (GB), pp.1-2, 2014
Pieczyska E.A., Maj M., Kowalczyk-Gajewska K., Staszczak M., Tobushi H., Hayashi S., Cristea M., Thermomechanical analysis of shape memory polymer under cyclic loading and relaxation conditions, ICEM-16, 16th International Conference on Experimental Mechanics, 2014-07-07/07-11, Cambridge (GB), pp.1-2, 2014

Abstract:
Experimental evaluation and modeling of a new polyurethane shape memory polymer (SMP) subjected to cyclic tension and stress-relaxation tests are presented. The influence of effects of thermomechanical couplings on the SMP thermomechanical behaviour for various strain rates was studied, basing on the sample temperature changes measured by a fast and sensitive infrared camera. The constitutive model valid in finite strain regime was developed following [5]. In the proposed approach SMP is described as a two-phase material composed of hyperelastic rubbery phase and elastic-viscoplastic glassy phase while the volume content of phases is specified by the current temperature.

Keywords:
Experimental evaluation, constitutive modeling, polyurethane shape memory polymer, cyclic tension, stress-relaxation tests, effects of thermomechanical couplings, thermomechanical behaviour, various strain rates, temperature changes, sensitive infrared camera, hyperelastic rubbery phase, elastic-viscoplastic glassy phase

11.Oliferuk W., Maj M., Energy storage rate components, SolMech 2014, 39th Solid Mechanics Conference, 2014-09-01/09-05, Zakopane (PL), pp.137-138, 2014
Oliferuk W., Maj M., Energy storage rate components, SolMech 2014, 39th Solid Mechanics Conference, 2014-09-01/09-05, Zakopane (PL), pp.137-138, 2014

Abstract:
Decomposition of energy storage rate into terms related to different deformation mechanisms has been presented. The energy storage rate is the ratio of the stored energy increment to the appropriate increment of plastic work. Experimental results show that the energy storage rate is dependent on plastic strain. This dependence is influenced by different microscopic deformation mechanisms. Then, the energy storage rate can be presented as a sum of particular components. Two of them are identified.

Keywords:
Energy storage rate, deformation mechanisms, statistically stored dislocations, geometrically necessary dislocations, long range internal stresses

12.Kowalczyk-Gajewska K., Pieczyska E.A., Maj M., Staszczak M., Majewski M., Cristea M., Tobushi H., Two-phase model of shape memory polymers at finite strains: formulation and experimental verification, SolMech 2014, 39th Solid Mechanics Conference, 2014-09-01/09-05, Zakopane (PL), pp.259-260, 2014
Kowalczyk-Gajewska K., Pieczyska E.A., Maj M., Staszczak M., Majewski M., Cristea M., Tobushi H., Two-phase model of shape memory polymers at finite strains: formulation and experimental verification, SolMech 2014, 39th Solid Mechanics Conference, 2014-09-01/09-05, Zakopane (PL), pp.259-260, 2014

Abstract:
A constitutive model of SMP, formulated at large strain format, is developed. SMP is described as a two-phase material composed of a soft rubbery phase and a hard glassy phase. The volume fraction of each phase is postulated as a logistic function of temperature. Identification of model parameters has been performed using the experimental tensile loading-unloading tests with different strain rates conducted at thermal chamber at different temperatures.

Keywords:
shape-memory polymers, two-phase model, large strain framework

13.Staszczak M., Pieczyska E.A., Maj M., Kowalczyk-Gajewska K., Cristea M., Tobushi H., Hayashi S., Estimation of shape fixity and shape recovery – crucial parameters for shape memory polymer applications, SolMech 2014, 39th Solid Mechanics Conference, 2014-09-01/09-05, Zakopane (PL), pp.267-268, 2014
Staszczak M., Pieczyska E.A., Maj M., Kowalczyk-Gajewska K., Cristea M., Tobushi H., Hayashi S., Estimation of shape fixity and shape recovery – crucial parameters for shape memory polymer applications, SolMech 2014, 39th Solid Mechanics Conference, 2014-09-01/09-05, Zakopane (PL), pp.267-268, 2014

Abstract:
Shape memory polymers (SMP) are new unique and attractive materials which demonstrate shape memory properties. It means that the materials, as a result of an external stimulus such as temperature, can recover their original (permanent) shape from deformed (temporary) shape. The mechanical characteristics of SMP, e.g. the elastic modulus and the yield stress, change significantly below and above their glass transition temperature Tg. It can be explained by differences of molecular motion of the polymer chains below and above Tg [1, 2]. Two phenomena due to this can be observed in the SMP. The first one is a shape fixity which means that it is possible to fix a temporary shape by cooling the deformed SMP below Tg. The second phenomenon, called a shape recovery, denotes the property that the original shape, changed due to deformation, is recovered during subsequent heating above the SMP Tg temperature. Preliminary estimation of these two parameters, crucial to assess SMP potential applications, is the subject of this paper [1].

Keywords:
Shape memory polymers, elastic modulus, yield stress, glass transition temperature, shape fixity, shape recovery

14.Pieczyska E., Tobushi H., Hayashi S., Maj M., Kowalczyk-Gajewska K., Staszczak M., Cristea M., Thermomechanical Analysis of Shape Memory Polyurethane, 4th Integrity, Reliability and Failure of Mechanical Systems, 2013-06-23/06-27, Funchal (PT), pp.1-2, 2013
Pieczyska E., Tobushi H., Hayashi S., Maj M., Kowalczyk-Gajewska K., Staszczak M., Cristea M., Thermomechanical Analysis of Shape Memory Polyurethane, 4th Integrity, Reliability and Failure of Mechanical Systems, 2013-06-23/06-27, Funchal (PT), pp.1-2, 2013

Abstract:
This paper presents experimental evaluation of a new polyurethane shape memory polymer (PU-SMP) produced by SMP Technologies Inc. It discusses mechanical characteristics and temperature changes of the SMP specimens subjected to tension test performed at room temperature with various strain rates. Basing on the mechanical data and the relevant temperature changes, we have studied the thermomechanical properties of the PU-SMP and influence of the strain rate on the strain localization behavior. Finally, we have identified the material parameters for the one-dimensional rheological model of the SMP.

Keywords:
shape memory polyurethane, tension test, dynamic mechanical analysis, infrared camera, temperature change, thermomechanical properties, rheological model

15.Pieczyska E.A., Tobushi H., Hayashi S., Maj M., Staszczak M., Shape memory alloys and polymers studied in tension by advanced infrared technique, DAS 30, 30th Danubia-Adria-Symposium on Advances in Experimental Mechanics, 2013-09-25/09-28, Primosten (HR), Vol.1, pp.24-25, 2013
Pieczyska E.A., Tobushi H., Hayashi S., Maj M., Staszczak M., Shape memory alloys and polymers studied in tension by advanced infrared technique, DAS 30, 30th Danubia-Adria-Symposium on Advances in Experimental Mechanics, 2013-09-25/09-28, Primosten (HR), Vol.1, pp.24-25, 2013

Abstract:
In order to contribute to solving the problems of recourses, energy and environment of the earth, the development of multifunctional smart materials is required. In the intelligent materials, investigation of shape memory alloy (SMA) and shape memory polymer (SMP) has attracted high attention due to their functional properties and high potential in practical applications. In SMA, the shape memory property appears based on the martensitic transformation (MT) in which the crystal structure varies depending on the variation in stress or temperature. In SMP, the elastic modulus and the yield stress are high at temperatures below the glass transition temperature Tg and low at temperatures above Tg. The shape memory property appears based on the glass transition in which the characteristics of molecular motion vary depending on the variation in temperature. Among the shape memory polymers, the polyurethane has been most often practically used.
In this paper, investigation of stress-induced martensitic transformation in TiNi SMA and thermomechanical behavior of SMP (Tg = 19 C) in tension at room temperature (22 C) are presented.

Keywords:
shape memory alloy, shape memory polymer, thermomechanical couplings, tensile test, strain localisation

16.Pieczyska E.A., Maj M., Kowalczyk-Gajewska K., Staszczak M., Mechanical and Infrared Thermography Analysis of Shape Memory Polyurethane, International Conference on Shape Memory and Superelastic Technologies, 2013-05-20/05-24, Praga (CZ), pp.282-283, 2013
Pieczyska E.A., Maj M., Kowalczyk-Gajewska K., Staszczak M., Mechanical and Infrared Thermography Analysis of Shape Memory Polyurethane, International Conference on Shape Memory and Superelastic Technologies, 2013-05-20/05-24, Praga (CZ), pp.282-283, 2013

Abstract:
Initial experimental evaluation of a new polyurethane shape memory polyner (PU-SMP) subjected to uniaxial tension carrięd out at different stlain rates is presented. The stress and strain data were recorded and temperature changes from the SMP specimen surface was deternrined using fast and sensitive infrared camera. Basing on themechanical characteristics and their relevant temperature changes, the SMP thernromechanical properties have been stLrdied. lnfluence of the strain rate on the SMP temperature, its structure and behaviour are discussed. Identification of the PU-SMP parameters for onc-dimensional rheological model proposed by Tobushi et. ttl. will be performed.

Keywords:
Shape memory polymers, elastic modulus, yield stress, glass transition temperature

17.Staszczak M., Pieczyska E.A., Maj M., Urbański L., Tobushi H., Hayashi S., Właściwości mechaniczne oraz zmiany temperatury polimeru z pamięcią kształtu w procesie rozciągania, TTP2013, X Konferencja TERMOGRAFIA I TERMOMETRIA W PODCZERWIENI, 2013-09-24/09-26, Lwów (UA), Vol.1, pp.91-92, 2013
Staszczak M., Pieczyska E.A., Maj M., Urbański L., Tobushi H., Hayashi S., Właściwości mechaniczne oraz zmiany temperatury polimeru z pamięcią kształtu w procesie rozciągania, TTP2013, X Konferencja TERMOGRAFIA I TERMOMETRIA W PODCZERWIENI, 2013-09-24/09-26, Lwów (UA), Vol.1, pp.91-92, 2013

Abstract:
W pracy przedstawiono wyniki badań efektów sprzężeń termomechanicznych poliuretanu z pamięcią kształtu podczas rozciągania z różnymi prędkościami. Zależności zmiany temperatury próbek od czasu wyznaczano za pomocą kamery termograficznej. Zaobserwowano dużą wrażliwość charakterystyk mechanicznych i zmian temperatury poliuretanu na prędkość deformacji. Wykorzystując efekt piezokaloryczny wyznaczano granice plastyczności dla różnych prędkości odkształcenia. Pokazano, że metoda bazująca na minimum temperatury próbki jest przydatna do wyznaczania granicy plastyczności materiałów polimerowych wykazujących nieliniową sprężystość.

Keywords:
poliuretan z pamięcią kształtu, efekty sprzężeń termomechanicznych, kamera termograficzna, efekt piezokaloryczny, granica plastyczności