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Innovative Shape Memory Polymer investigated by IRT and DIC during loading process
by E.A. Pieczyska, M. Staszczak, M. Maj, S. Musiał, K. Takeda, M. Cristea and A.D. Lantada**
Institute of Fundamental Technological Research PAS, Warsaw, Poland
* Aichi Institute of Technology, Toyota-city, Japan
** Institute of Macromolecular Chemistry, "Petru Poni" Iassy, Romania
*** Universidad Politécnica de Madrid (UPM), Madrid, Spain
Shape memory polymers (SMPs) are stimuli-responsive multifunctional materials that can change their shape in a predefined manner under an applied external stimulus, e.g. temperature change. The mechanism is related to the fact that the elastic modulus changes dramatically at the temperatures above and below their glass transition temperature Tg - it is high at low and low at high temperature [1]. Particularly noteworthy is a new generation of multiple-shape memory polymers (mSMPs) that demonstrate the ability to memorize more than two various shapes. The goal is to design and investigate the shape memory micro-actuators (M-As) with triple or quadruple shape memory properties. The M-As are produced by additive and micromanufacturing technologies towards obtaining a product component with different polymerization degrees. To this end, different exposure times of different regions of the tested photopolymer are used. The actuation to trigger the shape change of 4D printed mSMPs is step-by-step heating to various temperatures. Such approach can extend the performance of 4D printed structures and facilitate the design and development of devices featuring intricate structures unattainable through traditional techniques. In this way their functionality is broadened, enabling miniaturization, crucial for robotic and biomedical applications.
The research concerns two SMPs - thermoplastic polyurethane shape memory polymer (PU-SMP) and thermoset photopolymer - shape memory epoxy (SMEp). Investigations addressed both polymer structure and mechanical/thermomechanical behavior—from elastic loading through plastic deformation, localization, to necking and damage—with Infrared Thermography (IRT) applied for the latter [2].
Measurement of the SMPs temperature field during the loading is performed using a fast and sensitive infrared camera FLIR A6753. The field evolution of the heat sources associated with the deformation process at various stages of the loading/deformation is determined experimentally. The displacement fields are measured by Digital Image Correlation (DIC) using the homemade algorithm implemented in the ThermoCorr software [2]. The developed method applied is based on the coupled displacement and temperature fields measured using the DIC and (IRT), incorporating principles of heat transfer theory [3].
REFERENCES
[1] Tobushi H., Matsui R., Takeda K., Pieczyska E.A., Mechanical Properties of Shape Memory Materials. Nova Science Publishers, New York, 2013
[2] Golasiński K., Maj M., Urbański L., Staszczak M., Gradys A. ,Pieczyska E., Experimental study of thermomechanical behaviour of Gum Metal during cyclic tensile loadings: the quantitative contribution of IRT and DIC, Quant Infrared Thermogr J., 1-18, 2023
[3] Musiał S., Maj M., Urbański L., Nowak M., Field analysis of energy conversion during plastic deformation of polycrystalline material, Int. J. Solids Struct., 238, 111411, 2022
Acknowledgments:
The research has been carried out with support of the Polish National Center of Science under Grant UMO-2024/53/B/ST8/03931
