Wojciech Moćko, Ph.D., Dr. Habil., Eng.

Department of Experimental Mechanics (ZMD)
position: project manager

Doctoral thesis
2005-04-20Zastosowanie scalonych przetworników obrazu do analizy kolorymetrycznej 
supervisor -- Prof. Wojciech Żagan, Ph.D., Dr. Habil., Eng., PW
733 
Habilitation thesis
2016-09-29Zastosowanie metody pręta Hopkinsona do analizy wpływu wstępnych obciążeń zmęczeniowych na lepko-plastyczne charakterystyki stali i stopów 
Recent publications
1.Moćko W., Radziejewska J., Sarzyński A., Strzelec M., Marczak J., Analysis of the plastic deformation of AISI 304 steel induced by the nanosecond laser pulse, OPTICS & LASER TECHNOLOGY, ISSN: 0030-3992, DOI: 10.1016/j.optlastec.2016.11.022, Vol.90, pp.165-173, 2017
Abstract:

The paper presents result of experimental and numerical tests of plastic deformation of austenitic steel generated by a nanosecond laser pulse. The shock wave generated by the laser pulse was used to induce local plastic deformation of the material. The study examined the possibility of using the process to develop a laser forming of materials under ultra-high strain rate. It has been shown that the laser pulse with intensity 2.5 GW/cm2 induces a repeatable plastic deformation of commercially available 304 steel without thermal effects on the surface

Keywords:

Laser pulse, Plastic deformations, Microstructure, Numerical simulations

Affiliations:
Moćko W.-other affiliation
Radziejewska J.-IPPT PAN
Sarzyński A.-other affiliation
Strzelec M.-other affiliation
Marczak J.-other affiliation
2.Moćko W., Grzywna P., Kowalewski Z.L., Radziejewska J., An influence of cyclic loading on the form of constitutive relationship for DP500 steel, MATERIALS AND DESIGN, ISSN: 0261-3069, DOI: 10.1016/j.matdes.2016.04.075, Vol.103, pp.183-193, 2016
Abstract:

Fatigue loading induces a microstructure evolution leading to the change of macroscopically observed mechanical behavior of a dual phase DP500 steel. It was assumed that stress–strain characteristic of a pre-fatigued material may be determined using constitutive equation taking into account damage parameter. To estimate development of the fatigue damage in specimen a variation of the inelastic strain component was applied.

The flat "dog-bone" specimens were initially loaded using stress controlled cycles. When the strain reached a given value the fatigue process was stopped. Subsequently, the specimens with introduced fatigue damage were subjected to tensile tests. Next, the Johnson-Cook's constitutive equation was calibrated separately for each pre-fatigue case. Finally, a new constitutive relationship, based on the Johnson-Cook's model was proposed. It reflects the hardening and softening effects by taking into account both a change in the dislocation structure and development of fatigue microdamage. Proposed model shows a very good agreement with experimental data.

Keywords:

Constitutive model, Dual-phase steel, Fatigue, Stress–strain curve, Fatigue damage, Inelastic strain

Affiliations:
Moćko W.-other affiliation
Grzywna P.-IPPT PAN
Kowalewski Z.L.-IPPT PAN
Radziejewska J.-other affiliation
3.Moćko W., Janiszewski J., Radziejewska J., Grązka M., Analysis of deformation history and damage initiation for 6082-T6 aluminium alloy loaded at classic and symmetric Taylor impact test conditions, INTERNATIONAL JOURNAL OF IMPACT ENGINEERING, ISSN: 0734-743X, DOI: 10.1016/j.ijimpeng.2014.08.015, Vol.75, pp.203-213, 2015
Abstract:

Taylor impact tests in the classic and symmetric configurations were applied to analyse the development of plastic deformation and damage in Al-6082-T6 rods. Deformation histories during impact were recorded using high-speed photography, while internal axial damage was identified using metallography. The axial damage observed during the symmetric test were initiated during stress triaxiality peaks under tensile loading conditions. Variations of the stress state are the result of superimposed lateral mechanical waves reflected from the perimeter of the specimen. The fracture strain decreases with the increase of the stress triaxiality; it is thus possible to initiate damage at relatively low strain values under high-stress triaxiality values. During classic Taylor test because of the deflection of the elastic steel anvil in the rod on anvil test, the oscillations are smaller and quickly damped in comparison to the rod on rod experiment. Therefore, the initiation of axial damage is impossible. The cracks on the specimen edge are due to tensile loadings. For both the symmetric and classic Taylor tests, the damage conditions are comparable, i.e., a stable increase of strain combined with tensile loadings.

Keywords:

Taylor impact, Numerical modelling, High-speed photography, Damage initiation, Constitutive relation

Affiliations:
Moćko W.-other affiliation
Janiszewski J.-other affiliation
Radziejewska J.-IPPT PAN
Grązka M.-other affiliation
4.Moćko W., Brodecki A., Radziejewska J., Effects of pre-fatigue on the strain localization during tensile tests of DP 500 steel at low and high strain rates, JOURNAL OF STRAIN ANALYSIS FOR ENGINEERING DESIGN, ISSN: 0309-3247, DOI: 10.1177/0309324715599132, Vol.50, No.8, pp.571-583, 2015
Abstract:

The analysis involved subjecting DP 500 steel to pre-fatigue loads, and then tension at high strain rates using Hopkinson bar. Digital image correlation method was used to investigate how the pre-fatigue loads change the strains’ distribution on the surface of the sample subjected to tension. The analysis involved both films recorded at low rates of deformation (1.0 × 10−2 s−1) using ARAMIS system and the images captured with a high-speed camera during dynamic deformations with a Hopkinson bar (6.0 × 102 s−1). It was noted, based on the micro-structural analysis, that pre-fatigue loads cause the formation of micro-damages in the examined material. Thus, macroscopically observed stress–strain characteristic as well as Huber–Mises substitute strains’ distribution determined locally by the image correlation method is also subject to changes. The observed effects include the following: reduction of deformation corresponding to the tensile strength, decrease in elongation at break, and increase in yield limit and tensile strength. The observed effects are intensified with an increased stress value and pre-fatigue cycles’ number. Furthermore, these phenomena are more intensive in the conditions of dynamic deformation.

Keywords:

Hopkinson bar, fatigue, viscoplastic response, damage, stress–strain, tensile, high strain rate

Affiliations:
Moćko W.-other affiliation
Brodecki A.-Motor Transport Institute (PL)
Radziejewska J.-IPPT PAN
5.Moćko W., The influence of stress-controlled tensile fatigue loading on the stress–strain characteristics of AISI 1045 steel, MATERIALS AND DESIGN, ISSN: 0261-3069, DOI: 10.1016/j.matdes.2014.02.021, Vol.58, pp.145-153, 2014
Abstract:

This study analyses the influence of fatigue loading on the residual tensile properties of AISI 1045 steel. The fatigue tests were carried out under stress-controlled tensile loadings at a stress ratio equal to 0. The maximum applied stresses were within the range from 550 MPa to 790 MPa. An analysis of ratcheting strain and plastic strain amplitude evolution due to fatigue loading was performed on the experimental data. In the next stage of this study, the initial fatigue loadings were introduced. Two maximum stresses, 550 MPa and 750 MPa, and three cycle lengths, 25%, 50% and 75% of the total number of cycles required to fracture the material at a given stress, were used. The pre-fatigued specimens were subjected to tensile testing at strain rates from 10−4 to 100 s−1. A large number of fatigue cycles, equal to 75% of the fatigue life, induces material softening as well as a drop in elongation and a reduction of area. Pre-fatigue at maximum stress equal to 550 MPa results in the increase of the elastic limit and offset yield point as well. Both parameters reach almost constant value after number of cycles equal to 25 % of the fatigue life. The further increase in the number of cycles does not affect elastic limit and offset yield point in a clearly visible way. The increase of maximum stress of the initial fatigue loadings up to 750 MPa induces similar but stronger effect i.e. increase and stabilization of elastic limit and offset yield point values, however decrease of both parameters value is observed at large number of pre-fatigue cycles corresponding to 75% of the fatigue life.

Keywords:

Pre-fatigue, Cumulative fatigue damage, Stress–strain, Tensile test, Strain rates

Affiliations:
Moćko W.-other affiliation
6.Moćko W., Comparison of energy absorption properties of high nitrogen austenitic steel and cast alloy determined using low velocity perforation test, ARCHIVES OF METALLURGY AND MATERIALS, ISSN: 1733-3490, DOI: 10.2478/amm-2014-0011, Vol.59, No.1, pp.65-69, 2014
Abstract:

The results of energy absorbing analysis of VP159 austenitic steel and LH556 cast alloy were presented in this article. The assessment was carried out on the basis of drop-weight tower perforation test at impact energy equal to 500J and striker velocity equal to 12,5 m/s. Moreover, the basic mechanical properties of both tested materials were estimated in order to calibrate coefficients of the Johnson-Cook visco-plasticity model and Johnson-Cook damage initialization criterion as well. Subsequently, both models were applied for the finite element method simulation of perforation process. The reasonable agreement between measured and calculated shape of energy absorption curves were obtained for steel and cast alloy as well.

Keywords:

Energy absorption, austenitic steel, cast alloy, constitutive modeling, damage initiation criterion

Affiliations:
Moćko W.-other affiliation
7.Moćko W., Szymańska M., Śmietana M., Kalisz M., Simulation of nanoindentation experiments of single-layer and double-layer thin films using finite element method, Surface and Interface Analysis, ISSN: 0142-2421, DOI: 10.1002/sia.5473, Vol.46, No. ECASIA Special issue paper, pp.1071-1076, 2014
Abstract:

In this work, we focused on investigations of mechanical properties of SiNx and diamond-like carbon thin films deposited by plasma-enhanced chemical vapour deposition method for application in optical devices or solar cells. Mechanical properties of thin films deposited on clean and oxidized silicon substrates were determined by nanoindentation. The main difficulty with the characterization of thin films using nanoindentation method is related to the influence of the substrate on the measured properties of thin layers. We proposed a method to determine the mechanical properties (hardness and Young's modulus) of thin films in single-layer/substrate or double-layer/substrate system through combining the finite element method, nanoindentation experiments and numerical simulations. In this study, a three-dimensional numerical model of nanoindentation tests performed with Vickers diamond indenter was examined to determine the stress distributions during measurement with various maximum loads. The hardness and Young's modulus of the examined layers were determined using two types of procedures, depending on the von Mises equivalent stress distribution obtained at the maximum load. If the size of an elastically deformed region was sufficiently small compared with the thickness of the measured layers, we applied a standard method of measuring at the depth equal to 10% of the layer thickness; otherwise, an approximation method was used to reduce the substrate influence.

Keywords:

silicon nitride, DLC, PECVD, mechanical properties, nanoindentation, FEM

Affiliations:
Moćko W.-IPPT PAN
Szymańska M.-other affiliation
Śmietana M.-other affiliation
Kalisz M.-other affiliation
8.Moćko W., Kowalewski Z.L., Evolution of tensile properties of the tial6v4 alloy due to the prior cyclic loading history, JOURNAL OF THEORETICAL AND APPLIED MECHANICS, ISSN: 1429-2955, Vol.52, No.3, pp.847-851, 2014
Keywords:

fatigue, metals and alloys, deformation and fracture, cumulative fatigue damage

Affiliations:
Moćko W.-other affiliation
Kowalewski Z.L.-IPPT PAN
9.Moćko W., Janiszewski J., Grązka M., Application of an extended Rusinek-Klepaczko constitutive model to predict the mechanical behavior of 6082-T6 aluminum under Taylor impact test conditions, JOURNAL OF STRAIN ANALYSIS FOR ENGINEERING DESIGN, ISSN: 0309-3247, DOI: 10.1177/0309324713488885, Vol.48, No.6, pp.364-375, 2013
Abstract:

The application of an extended Rusinek–Klepaczko constitutive equation to predict the mechanical response of 6082-T6 aluminum under the Taylor impact test conditions was presented in this article. The numerical results obtained in the study were verified through a comparison with the experimental data extracted from the Taylor anvil-on-rod impact experiments. It was concluded that the extended Rusinek–Klepaczko constitutive model predicts the behavior of the tested aluminum alloy under applied loading conditions with satisfactory accuracy. Moreover, it was found that the plastic wave phenomenon in this material is very limited and that there was no region of constant plastic wave velocity. Strain rates up to 1.6 × 104 s−1 were recorded during the Taylor impact experiments; therefore, this value may be set as the upper limit of the extended Rusinek–Klepaczko model for the alloy, which was validated with the anvil-on-rod experiment.

Keywords:

Taylor test, split Hopkinson pressure bar, direct impact compression test, 6082-T6 aluminum alloy, plastic wave propagation

Affiliations:
Moćko W.-other affiliation
Janiszewski J.-other affiliation
Grązka M.-other affiliation
10.Moćko W., Kowalewski Z.L., Application of FEM in the assessment of phenomena associated with dynamic investigations on a miniaturised ICT testing stand, KOVOVE MATERIALY-METALLIC MATERIALS, ISSN: 0023-432X, Vol.51, pp.71-82, 2013
Abstract:

This paper presents the assembly of the miniaturised direct impact compression test method (MDICT) developed at the Institute of Fundamental Technological Research at the Polish Academy of Sciences (IFTR PAS). Additionally, this method was used to investigate the mechanical properties of tantalum at the strain rate of 8×10^5 s−1 .To analyse the phenomena occurring during the tests, a numerical model of the testing stand was developed and validated. The finite element (FEM) model was expanded to estimate the sources of error achieved in the results using the analytical methods. The effects related to friction, inertia, specimen ratio, adiabatic heating, stress equilibration and strain rate on the stress-strain characteristic observed before and after the analytical correction were discussed.

Keywords:

miaturised Hopkinson bar, tantalum, high strain rates, direct impact, finite element method

Affiliations:
Moćko W.-IPPT PAN
Kowalewski Z.L.-IPPT PAN
11.Moćko W., Kowalewski Z.L., Perforation test as an accuracy evaluation tool for a constitutive model of austenitic steel, ARCHIVES OF METALLURGY AND MATERIALS, ISSN: 1733-3490, DOI: 10.2478/amm-2013-0133, Vol.58, No.4, pp.1105-1110, 2013
Abstract:

In this paper, a new method for assessing the accuracy of a constitutive model is proposed. The method uses perforation test done by drop weight tower. The assessment is carried out by comparison of striker velocity curve obtained using experiment and FEM simulation. In order to validate proposed method the various constitutive equations were applied i.e. Johnson-Cook, Zerilli-Armstrong and the extended Rusinek-Klepaczko to model mechanical behaviour of X4CrMnN16-12 austenitic steel. The steel was characterized at wide range of strain and strain rates using servo-hydraulic testing machine and split Hopkinson pressure bar. The relative error calculated as a difference between measured and constitutive model based stress-strain curve was applied as a reference data (classic approach). Subsequently, it was compared with relative error determined on the basis of experimental and FEM calculated striker velocity (new approach). A good correlation between classic and a new method was found. Moreover, a new method of error assessment enables to validate constitutive equation in a wide range of strain rates and temperatures on the basis of a single experiment.

Keywords:

plastic behaviour, fracture properties, constitutive modeling, perforation, austenitic steel

Affiliations:
Moćko W.-other affiliation
Kowalewski Z.L.-IPPT PAN
12.Moćko W., Analysis of the impact of the frequency range of the tensometer bridge and projectile geometry on the results of measurements by the split Hopkinson pressure bar method, METROLOGY AND MEASUREMENT SYSTEMS, ISSN: 0860-8229, DOI: 10.2478/mms-2013-0047, Vol.XX, No.4, pp.555-564, 2013
Abstract:

The paper presents the results of the analysis of the striker shape impact on the shape of the mechanical elastic wave generated in the Hopkinson bar. The influence of the tensometer amplifier bandwidth on the stress-strain characteristics obtained in this method was analyzed too. For the purposes of analyzing under the computing environment ABAQUS / Explicit the test bench model was created, and then the analysis of the process of dynamic deformation of the specimen with specific mechanical parameters was carried out. Based on those tests, it was found that the geometry of the end of the striker has an effect on the form of the loading wave and the spectral width of the signal of that wave. Reduction of the striker end diameter reduces unwanted oscillations, however, adversely affects the time of strain rate stabilization. It was determined for the assumed test bench configuration that a tensometric measurement system with a bandwidth equal to 50 kHz is sufficient

Keywords:

Hopkinson bar, tensometer bridge, amplifier bandwidth, strain measurement

Affiliations:
Moćko W.-IPPT PAN
13.Moćko W., Kaźmierczak P., Kalisz M., Influence of the lighting surface and luminance of the brake lamp on the observation comfort, PRZEGLĄD ELEKTROTECHNICZNY, ISSN: 0033-2097, Vol.89, No.1a, pp.116-121, 2013
14.Moćko W., Gis W., Development and validation of model of the electric car energy consumption, PRZEGLĄD ELEKTROTECHNICZNY, ISSN: 0033-2097, Vol.89, No.11, pp.141-143, 2013
Abstract:

This paper presents the proposed new model of energy consumption by electric car, determined based on the course of the velocity. The model has been verified by comparing with the results obtained on a chassis dynamometer under the conditions described in the New European Driving Cycle (NEDC). A good compliance with both momentary and total electrical energy consumption while driving was obtained. The model can be used to analyze the distribution of charging stations locations that will allow quick charging or replacement of traction batteries to extend the range of electric cars.

Keywords:

electric car, energy consumption, traction batteries, chassis dynamometer

Affiliations:
Moćko W.-other affiliation
Gis W.-other affiliation
15.Moćko W., Szymczak T., Kowalewski Z.L., Mechanical Properties of AW8S-V Polyester Composite under Various Loading Conditions, ENGINEERING TRANSACTIONS (ROZPRAWY INŻYNIERSKIE), ISSN: 0867-888X, Vol.61, No.4, pp.289-300, 2013
Abstract:

This article presents the results of an analysis of the mechanical properties of the AW8S-V polyester composite reinforced by a roving fabric under tensile loading. The stress-strain curves show an increase of the maximum stress and elastic modulus with increasing strain rate. By contrast, an increase of the temperature led to decrease of the maximum stress and elastic modulus. It is also shown that, failure mechanisms are dependent on the loading type. Shear cracks occurred in the specimens under quasi-static loading whereas composite layers damage was observed under dynamic loading. Temperature increase resulted to stronger fragmentation of the specimens.

Keywords:

polyester composite, Hopkinson bar, high strain rate, damage

Affiliations:
Moćko W.-other affiliation
Szymczak T.-Bialystok University of Technology (PL)
Kowalewski Z.L.-IPPT PAN
16.Moćko W., Ornowski M., Szymańska M., Badanie zużycia energii przez samochód elektryczny w czasie testów drogowych, ZESZYTY PROBLEMOWE - MASZYNY ELEKTRYCZNE, ISSN: 0239-3646, Vol.99, No.2, pp.31-35, 2013
17.Moćko W., Szymańska M., Wojciechowski A., Opracowanie i kalibracja modelu matematycznego akumulatorów trakcyjnych przeznaczonych do samochodu elektrycznego, ZESZYTY PROBLEMOWE - MASZYNY ELEKTRYCZNE, ISSN: 0239-3646, Vol.99, No.2, pp.25-30, 2013
18.Moćko W., Szymańska M., Kalisz M., Model elektryczny ładowania akumulatorów trakcyjnych za pomocą energii z ogniw fotowoltaicznych, ELEKTRONIKA - KONSTRUKCJE, TECHNOLOGIE, ZASTOSOWANIA, ISSN: 0033-2089, Vol.7, pp.45-46, 2013
19.Moćko W., Kruszka L., Results of strain rate and temperature on mechanical properties of selected structural steels, Procedia Engineering, ISSN: 1877-7058, DOI: 10.1016/j.proeng.2013.04.100, Vol.57, pp.789-797, 2013
Abstract:

The article presents results of application of Rusinek-Klepaczko (RK) constitutive equation for the purposes of modelling of mechanical behaviour of four grades of structural steels. In order to calibrate the RK model a series of compression tests at wide range of strain rates were carried out using two testing stands: servo-hydraulic machine and split Hopkinson bar. The results were analysed to determine influence of temperature and strain rate on visco-plastic response of tested steels. It was concluded that at low temperatures the thermally activated mechanisms of plastic deformation results in the strong strain rate hardening effects, whereas at high temperatures they are limited.

Keywords:

Structural steels, Rusinek-Klepaczko constitutive model, Hopkinson bar, High strain rates

Affiliations:
Moćko W.-other affiliation
Kruszka L.-Military University of Technology (PL)
20.Moćko W., Rodriguez-Martinez J.A., Kowalewski Z.L., Rusinek A., Compressive Viscoplastic Response of 6082-T6 and 7075-T6 Aluminium Alloys Under Wide Range of Strain Rate at Room Temperature: Experiments and Modelling, STRAIN, ISSN: 0039-2103, Vol.48, pp.498-509, 2012
21.Moćko W., Kowalewski Z.L., Dynamic Properties of Aluminium Alloys Used in Automotive Industry, JOURNAL OF KONES, ISSN: 1231-4005, Vol.19, No.2, pp.345-351, 2012
Abstract:

Around 20% of CO2 emitted as a result of human activity on Earth comes from transportation. One of the ideas, which lead to diminishing of the greenhouse gases e mission, is reducing of fuel consumption. It may be achieved by introducing a new powertrain solutions as well as lowering overall vehicle weight. The reduction of vehicle weight may be obtained by both a new design of part and structures and application of a new materials i.e. aluminium alloys. It has to be emphasised that weight reduction is very important for combustion engine driven vehicles and electric driven vehicles as well. Mass lowering is especially desirable in the case of electric vehicles because they typically have a very narrow operational range usually lower than 200 km. Therefore even small weight reduction de creases energy consumption of EV and as a consequence increases its range, which is a crucial parameter for users.
The results presented in this article were focused on high strength aluminium alloys of 6082-T6 and 7075-T6 types. Applying of those materials enables mass lowering of structures up to 50%, maintaining original functionality. Moreover, aluminium alloys may be also used in energy absorbing structures. The goal of tests was to obtain data required in FE analysis. In order to simulate dynamic phenomenon i.e. vehicle crash investigation of the stress-strain curves of alloys were carried out at wide range of strain rates using Hopkinson bar.

Keywords:

road transport, simulation, combustion engines, air pollution, environmental protection

Affiliations:
Moćko W.-IPPT PAN
Kowalewski Z.L.-IPPT PAN
22.Barnat W., Kordys M., Moćko W., Dybcio P., Panowicz R., Numerical simulation of dynamic weld compression, JOURNAL OF KONES, ISSN: 1231-4005, Vol.19, No.2, pp.35-43, 2012
23.Staniak P., Iwański G., Moćko W., Koncepcja modułowego elektronicznego systemu przekształcania energii paneli fotowoltaicznych dla stacji wymiany akumulatorów trakcyjnych, ELEKTRONIKA - KONSTRUKCJE, TECHNOLOGIE, ZASTOSOWANIA, ISSN: 0033-2089, Vol.7, pp.99-101, 2012
24.Moćko W., Wojciechowski A., Staniak P., Zastosowanie odnawialnych źródeł energii w transporcie, ZESZYTY PROBLEMOWE - MASZYNY ELEKTRYCZNE, ISSN: 0239-3646, Vol.95, No.2, pp.99-105, 2012
25.Moćko W., Kowalewski Z.L., Wojciechowski A., Rudnik D., Badania właściwości mechanicznych staliwa LH556 i stali VP159 pod kątem zastosowania w osłonach balistycznych, BIULETYN WOJSKOWEJ AKADEMII TECHNICZNEJ, ISSN: 1234-5865, Vol.LXI, No.2, pp.449-462, 2012
Abstract:

Praca przedstawia charakterystyki naprężenie-odkształcenie stali austenitycznej VP159 oraz staliwa austenitycznego LH556, o dużej zawartości azotu, przy różnych prędkościach odkształcania. Do badań w zakresie obciążeń statycznych zastosowano serwohydrauliczną maszynę wytrzymałościową, natomiast w zakresie obciążeń dynamicznych metodę pręta Hopkinsona. Otrzymane rezultaty przedstawiono w formie wykresów naprężenia rzeczywistego w funkcji odkształcenia rzeczywistego. Na podstawie statycznej próby rozciągania wyznaczono również podstawowe parametry badanych materiałów, takie jak: E, R0,05, R0,2, Rm. Na podstawie badań stwierdzono, że stal VP159 ma znacznie lepszą ciągliwość niż staliwo LH556, natomiast pozostałe parametry i charakterystyki były zbliżone. Otrzymane wyniki można wykorzystać do wyznaczenia parametrów równań konstytutywnych opisujących termomechaniczne właściwości materiałów na potrzeby symulacji komputerowych.

Keywords:

mechanika, pręt Hopkinsona, duże prędkości odkształcania, stal wysokoazotowa, charakterystyka naprężenie-odkształcenie

Affiliations:
Moćko W.-IPPT PAN
Kowalewski Z.L.-IPPT PAN
Wojciechowski A.-other affiliation
Rudnik D.-other affiliation
26.Moćko W., Kowalewski Z.L., Zastosowanie wybranych równań konstytutywnych do opisu właściwości mechanicznych stali wysokoazotowej typu VP159, MODELOWANIE INŻYNIERSKIE, ISSN: 1896-771X, Vol.12, No.43, pp.203-210, 2012
27.Moćko W., Kowalewski Z.L., Dynamic Compression Tests – Current Achievements and Future Development, ENGINEERING TRANSACTIONS (ROZPRAWY INŻYNIERSKIE), ISSN: 0867-888X, Vol.59, No.3, pp.235-248, 2011
28.Moćko W., Kowalewski Z.L., Opracowanie i weryfikacja modelu MES zminiaturyzowanego stanowiska do badań metodą bezpośredniego uderzenia pocisku w próbkę, TRANSPORT SAMOCHODOWY, ISSN: 1731-2795, Vol.2, pp.97-105, 2011
29.Moćko W., Kowalewski Z.L., Mechanical Properties of the A359/SiCp metal matrix composite at wide range of strain rates, APPLIED MECHANICS AND MATERIALS, ISSN: 1662-7482, Vol.82, pp.166-171, 2011

Conference papers
1.Moćko W., Effects of Cumulative Fatigue Damage under Tensional Cyclic Loading on the Constitutive Relation of AISI 1045 Steel, 4th International Conference on Nonlinear Dynamics, 2013-06-19/06-22, Sevastopol (UA), pp.412-418, 2013
2.Szymańska M., Kalisz M., Śmietana M., Moćko W., Wyznaczanie twardości warstw azotku krzemu i DLC wytworzonych metodą RF PECVD, XII Krajowa Konferencja Elektroniki, 2013-06-10/06-13, Darłówko Wschodnie (PL), Vol.II, pp.74-79, 2013
3.Moćko W., Kowalewski Z.L., Impact resistance of VP159 high nitrogen steel, ICEM15, 15th International Conference on Experimental Mechanics, 2012-07-22/07-27, Porto (PT), No.1, pp.613-614, 2012
Abstract:

This work presents the impact resistance results of investigation on the VP159 high nitrogen steel. The tests were carried out using the Instron impact system at the projectile velocity equal to 12,5 m/s. The experimental results were compared to the FE predictions. The Rusinek-Klepaczko constitutive model was applied to describe mechanical response of tested material. It was concluded that the FE results were in a good agreement with the experiment.

Affiliations:
Moćko W.-IPPT PAN
Kowalewski Z.L.-IPPT PAN
4.Pieczyska E.A., Tobushi H., Takeda K., Kulasiński K., Kowalewski Z.L., Moćko W., Luckner J., Temperature assessment of TiNi shape memory alloy subjected to compression at quasistatic and dynamic strain rates, ICEM15, 15th International Conference on Experimental Mechanics, 2012-07-22/07-27, Porto (PT), No.1, pp.1145-1146, 2012
Abstract:

This work compares the thermomechanical behavior of TiNi shape memory alloy subjected to the compression test performed under various strain rates. The mechanical characteristics of the material were elaborated. The specimen temperature changes related to the exothermic martensitic forward and endothermic reverse transformation were measured in a contact-less manner by a very fast and sensitive infrared camera. It has been found that in this experimental conditions the stress-induced transformation and reorientation processes occurred homogeneously, since the temperature distribution observed on the specimen surface was uniform. The obtained temperature variation depends on the strain rate applied. At the higher strain rate the higher temperature changes were obtained, because the heat flow to the surroundings was lower and the process was closer to adiabatic conditions. The temperature changes influence significantly the SMA stress-strain curves and their mechanical properties.

Keywords:

shape memory alloy, various strain rates, compression tests, exothermic martensitic forward, endothermic reverse transformation, fast and sensitive infrared camera

Affiliations:
Pieczyska E.A.-IPPT PAN
Tobushi H.-Aichi Institute of Technology (JP)
Takeda K.-Aichi Institute of Technology (JP)
Kulasiński K.-IPPT PAN
Kowalewski Z.L.-IPPT PAN
Moćko W.-IPPT PAN
Luckner J.-IPPT PAN
5.Staniak P., Iwański G., Moćko W., Układ przekształcania energii paneli fotowoltaicznych na potrzeby systemu ładowania baterii elektrochemicznych, III Sympozjum “Fotowoltaika i Transparentna Elektronika – Perspektywy Rozwoju”, 2012-03-29/04-01, Świeradów-Zdrój (PL), Vol.1, pp.118-126, 2012
6.Moćko W., Kowalewski Z.L., Application of miniaturized direct impact compression method in characterization of mechanical behavior of materials, Annual International Workshop on Dynamic Behaviour of Structures and Materials, 2011-06-13/06-15, Metz (FR), Vol.1, pp.1-6, 2011
Abstract:

The paper presents the results of tests on polycrystalline tantalum at very high strain rates (7.5x104 s-1). The measurements were carried out using miniaturized Direct Impact Compression Test (DICT) method. The transmitting bar diameter was 3mm, and the tested specimens were cylindrical shape of 1.5 mm diameter and 0.55 mm thickness. A numerical model of the testing stand was developed in the ABAQUS environment to trace the phenomena occurring during specimen deformation and to evaluate their influence on the final result. The test stand dimensions and the test parameters used in the calculations were this same as for DICT experiments. The results of computer simulations demonstrated good agreement with experimental results, which proves that the Finite Element Method (FEM) reproduces well the behavior of the stand and can be applied in analyses performed to find the reasons of errors in plastic stress flow measurements.

Keywords:

Direct Impact Compression Tests, Tantalum, high strain rates, compression tests, Hopkinson bar

Affiliations:
Moćko W.-IPPT PAN
Kowalewski Z.L.-IPPT PAN

Conference abstracts
1.Radziejewska J., Sarzyński A., Strzelec M., Hoffman J., Moćko W., Evaluation of dynamic hardness and adhesion of thin layer using nanosecond laser pulse, SolMech 2016, 40th Solid Mechanics Conference, 2016-08-29/09-02, Warszawa (PL), No.P232, pp.1-2, 2016
2.Moćko W., Grzywna P., Kowalewski Z.L., Radziejewska J., Constitutive behaviour of DP500 steel exposed to prior cyclic loadings, SolMech 2016, 40th Solid Mechanics Conference, 2016-08-29/09-02, Warszawa (PL), No.P188, pp.1-2, 2016
3.Libura T., Moćko W., Kowalewski Z.L., A new version of Hopkinson bar testing stand for determination of dynamic tensile characteristics, SolMech 2014, 39th Solid Mechanics Conference, 2014-09-01/09-05, Zakopane (PL), pp.311-312, 2014
4.Moćko W., Influence of the fatigue loadings on the residual stress-strain characteristic of the engineering materials, SolMech 2014, 39th Solid Mechanics Conference, 2014-09-01/09-05, Zakopane (PL), pp.163-164, 2014
5.Kruszka L., Moćko W., Cadoni E., Fenu L., Effect of fibre content on static and dynamic properties of fibre reinforced concrete, SolMech 2014, 39th Solid Mechanics Conference, 2014-09-01/09-05, Zakopane (PL), pp.127-128, 2014
6.Kruszka L., Kowalewski Z.L., Moćko W., Grązka M., Experimental analysis of dynamic plastic behavior of materials by the Hopkinson bar technique, Plasticity 2013, 19th International Symposium on Plasticity and Its Current Applications, 2013-01-03/01-08, Nassau (BS), pp.190-192, 2013
Abstract:

In this paper original experimental methodologies of dynamic plastic behavior of various structural materials in a wide range of strain rates up to 10 5 s - 1 , and at selected temperatures are presented. Identification of constitutive models and their verification are also included

Affiliations:
Kruszka L.-Military University of Technology (PL)
Kowalewski Z.L.-IPPT PAN
Moćko W.-other affiliation
Grązka M.-other affiliation
7.Kowalewski Z.L., Nowak Z., Moćko W., Direct impact compression test of tantalum – experimental investigation and model identification, SolMech 2012, 38th Solid Mechanics Conference, 2012-08-27/08-31, Warszawa (PL), pp.128-129, 2012
8.Moćko W., Kowalewski Z.L., Mechanical properties of selected aluminium alloys at wide range of strain rates, SolMech 2012, 38th Solid Mechanics Conference, 2012-08-27/08-31, Warszawa (PL), pp.136-137, 2012
9.Moćko W., Kowalewski Z.L., Compressive behavior of 6082-T6 and 7075-T6 aluminium alloys at very high strain rates, Workshop on Dynamic Behavior of Materials and Stafety Structures, 2012-05-02/05-04, Poznań (PL), pp.x1-x3, 2012
10.Moćko W., Kowalewski Z.L., Wojciechowski A., Numerical modelling of the miniaturized direct impact compression test method, 28th Danubia-Adria-Symposium on Advances in Experimental Mechanics, 2011-09-28/10-01, Siófok (HU), Vol.1, pp.119-120, 2011
11.Moćko W., Pietrzak K., Kowalewski Z.L., Stoberska K., Sienicki E., An analysis of mechanical behaviour of tantalum over a wide range of strain rate, SolMech 2010, 37th Solid Mechanics Conference, 2010-09-06/09-10, Warszawa (PL), pp.200-201, 2010