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| Effect of temperature gradient on the mechanical properties of thermotropic shape memory polymer plates |
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Abstract As a new type of intelligent material, shape memory polymer has been widely used in aerospace, biomedicine and other fields due to its superiorities in light weight, low cost, and large deformation recovery rate. Among them, the research on the mechanical behavior of thermotropic shape memory polymers is mostly focused on the overall temperature change, but the influence of temperature gradient is rarely considered. Existing studies have shown that the temperature gradient has a non-negligible effect on the mechanical properties of materials and the mechanical behavior of engineering structures. Based on the above, under the assumption of uniform stress, combined with heat transfer and thermally induced shape memory polymer phase transition constitutive theory, a new constitutive relationship considering temperature gradient is proposed. The rationality and accuracy of the model are verified by theoretical analysis and experimental test results ,In this work, The effect of continuously changing temperature gradient on the mechanical properties of shape memory polymer in one-dimensional transient heat conduction stage is discussed. The temperature field distribution varying with time and plate thickness position is determined by finite difference method, and the changes of storage strain, elastic modulus and stress at different thickness are analyzed.. In the one-dimensional steady-state heat conduction stage, the temperature gradient is a fixed value, the overall state under different boundary conditions is classified, and the changes in stored strain, elastic modulus and stress at different thicknesses in different states are simulated. The results show that when the temperature gradient changes continuously, the mechanical behavior of position changes significantly when its temperature is in the range where the phase transition occurs, so it should be specially monitored.When the temperature gradient is constant, the overall state and mechanical behavior will be affected by the boundary temperature conditions. The research in this work can not only provide ideas for monitoring the mechanical behavior of shape memory polymers and the realization of functional gradients under different heat conduction conditions, but also provide a theoretical basis for further engineering applications.
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Received: 02 July 2021
Published: 19 April 2022
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2022, Vol. 43 
