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A unified approach to thermo-mechano-caloric-characterization of elastocaloric materials
This paper presents a novel approach to characterizing the relevant mechanical, thermal and
caloric properties of elastocalorics material in a single testing device. Usually, tensile experiments
are performed to determine the rate- and process-depending stress/strain behavior of
nickel-titanium-based shape memory alloys and potentially other elastocaloric materials made
from metallic alloys. These tests are relevant for, e.g., characterization of hysteresis properties and
subsequent calculation of mechanical work input. In addition, simultaneous observation with an
infrared camera is useful to understand temperature evolution and maximum temperature changes
achievable during the loading/unloading process. Characterization of the caloric properties of the
materials determines latent heats and, together with the mechanical work, also the material
coefficient of performance. It is typically carried out via differential scanning calorimetry (DSC),
which is performed in a separate device and requires a second experiment with different types of
samples. Furthermore, DSC measurements do not reflect the way mechanically induced phase
transformations trigger the release and absorption of latent heats as it is the case for elastocalorics.
In order to provide a more consistent understanding of the relevant elastocaloric material
properties, we here present a novel method that (a) allows for a systematic determination of
load-dependent latent heats and (b) introduces a comprehensive testing setup and suitable testing
routine to determine the mechanical, thermal and caloric parameters in the same experimental
device and with the same sample, thus greatly simplifying the overall procedure