Leszek Urbański

Department of Mechanics of Materials (ZMM)
Thermoplasticity Laboratory (LT)
position: senior technician
telephone: (+48) 22 826 12 81 ext.: 405
room: 217
e-mail: lurban

Recent publications
1.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

Affiliations:
Staszczak M.-IPPT PAN
Pieczyska E.A.-IPPT PAN
Maj M.-IPPT PAN
Urbański L.-IPPT PAN
Odriozola I.-IK4-CIDETEC (ES)
Martin R.-IK4-CIDETEC (ES)
2.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

Affiliations:
Pieczyska E.A.-IPPT PAN
Maj M.-IPPT PAN
Kowalczyk-Gajewska K.-IPPT PAN
Staszczak M.-IPPT PAN
Urbański L.-IPPT PAN
Tobushi H.-Aichi Institute of Technology (JP)
Hayashi S.-SMP Technologies Inc. (JP)
Cristea M.-Petru Poni Institute of Macromolecular Chemistry (RO)
3.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

Affiliations:
Staszczak M.-IPPT PAN
Pieczyska E.A.-IPPT PAN
Maj M.-IPPT PAN
Urbański L.-IPPT PAN
Tobushi H.-Aichi Institute of Technology (JP)
Hayashi S.-SMP Technologies Inc. (JP)
4.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

Affiliations:
Oliferuk W.-IPPT PAN
Maj M.-IPPT PAN
Litwinko R.-other affiliation
Urbański L.-IPPT PAN

Conference papers
1.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

Affiliations:
Staszczak M.-IPPT PAN
Pieczyska E.A.-IPPT PAN
Maj M.-IPPT PAN
Urbański L.-IPPT PAN
Odriozola I.-IK4-CIDETEC (ES)
Martin R.-IK4-CIDETEC (ES)

Conference abstracts
1.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

Affiliations:
Kowalczyk-Gajewska K.-IPPT PAN
Frydrych K.-IPPT PAN
Maj M.-IPPT PAN
Urbański L.-IPPT PAN
2.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

Affiliations:
Staszczak M.-IPPT PAN
Pieczyska E.A.-IPPT PAN
Maj M.-IPPT PAN
Urbański L.-IPPT PAN
Tobushi H.-Aichi Institute of Technology (JP)
Hayashi S.-SMP Technologies Inc. (JP)