In recent years, elastocaloric cooling technology (ECT), based on the elastocaloric effect of shape memory materials (SMA), has emerged as one of the most promising alternatives to vapor compression cooling technology. The main limitation of ECT is its short fatigue life, which can be significantly improved if compressive loading is applied instead of tensile. One of the major challenges in the development of compression-loaded elastocaloric devices is to find a compromise between the capability of rapid heat transfer, which requires thin-walled structures, and the structural (in)stability to which such structures are prone. Thin-walled tubes with round cross-sections have shown the best compromise so far and have therefore been the main focus of this work. We have experimentally determined stable tube lengths of different cross-sections and defined two phase diagrams of buckling mode shapes. We found that temperature changes reduce the stability due to the elastocaloric effect. It has been shown that the use of intermediate supports increases the stability of long tubes. For the first time, a 3D shell finite element based on large deformation theory with incorporated SMA constitutive equations has been developed. A numerical model for predicting of instabilities of SMA tubes was developed and verified by the experimental results. The developed shell element can be used to model the response of arbitrary thin-walled SMA structures. Its applicability is therefore broader and can be used to design SMA components also in various branches of industry, such as medical, automotive, aerospace, etc.
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