20.500.12556/RUL-141266 Experimental investigation of buckling stability of superelastic Ni-Ti tubes under cyclic compressive loading towards defining functionally stable tubes for elastocaloric cooling Elastocaloric cooling technology recently attracted significant attention as an environmental friendly alternative to vapor-compression technology. It is based on the elastocaloric effect, which occurs in superelastic shape memory alloys (SMAs) during stress-induced martensitic transformation. To date, several proof-of-concept devices (mostly based on tensile loading) have been developed, but limited fatigue life was shown to be one of the major issues. Compressive loading improves the fatigue life of such devices significantly, but in return buckling of SMA structure might occur. To overcome this challenge, it is crucial to understand the buckling phenomena of SMA structures, especially for thin-walled tubes that seem to be ideal candidates for application in elastocaloric cooling devices. Here, we experimentally investigated the effects of the diameter-to-thickness ratio (D$_{out}$/t) and slenderness (λ) on buckling stability of Ni-Ti tubes that were subjected to cyclic compressive loading. In total, 161 superelastic Ni-Ti tubes with outer diameter (D$_{out}$) ranging from 2 mm to 3 mm, D$_{out}$/t ranging from 5 to 25 and gauge lengths (L$_g$) ranging from 6 to 20 mm were tested. The loading procedure consisted of 3 parts: (I) 1 isothermal full-transformation loading cycle, (II) 50 training cycles, and (III) 20 adiabatic cycles to simulate loading conditions in elastocaloric device. We constructed experimental phase diagrams of buckling modes in λ – D$_{out}$/t space for constant D$_{out}$ and in λ – D$_{out}$ space for constant D$_{out}$/t ratio. Marked areas of functionally stable tubes in these phase diagrams give the design guidance for future developments of durable and efficient elastocaloric devices and other applications, e.g. actuators and dampers. shape-memory materials elastocaloric effect stability of cylindrical shells shape-memory buckling mode shape cyclic loading compression materiali z oblikovnim spominom elastokalorični učinek stabilnost cilindričnih lupin true false true Angleški jezik Slovenski jezik Članek v reviji 2022-09-27 10:54:50 2022-09-27 10:54:51 2023-01-17 03:37:17 0000-00-00 00:00:00 2022 0 0 15 str. Vol. 256, art. 111948 Dec. 2022 0000-00-00 Zaloznikova Objavljeno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 539.3 0020-7683 10.1016/j.ijsolstr.2022.111948 122518275 Porenta...-Experimental_investigation_of_buckling_stability_of_superelastic_Ni-Ti_tubes_under_cyclic_compressive_loading.pdf Porenta...-Experimental_investigation_of_buckling_stability_of_superelastic_Ni-Ti_tubes_under_cyclic_compressive_loading.pdf 1 5BB286CD19C75DE55332733C89CBF918 7d9d8611fd5bc5106d99239fe35238ed548baedeec2864fdab09604151bbf598 fe5c2a33-3e42-11ed-9c94-00155dcfd717 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=162251 https://www.sciencedirect.com/science/article/pii/S0020768322004012 1 0b28124a-3e42-11ed-9c94-00155dcfd717 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=162250 Fakulteta za strojništvo 0 0 0