An isogeometric analysis-based investigation of the flexocaloric effect in functionally graded dielectrics

The increasing obligatory demand for clean and environment-friendly alternates for refrigeration and air-conditioning has made solid-state refrigeration more alluring for researchers of the relevant fields. The flexocaloric effect is a mechanism providing solid-state refrigeration in mechanically loaded samples. In this work, we explore the potential of functionally graded (FG) dielectric material with Ba_0.67Sr_0.33TiO₃ (BST) and polyvinylidene fluoride (PVDF) as its constituents to impart the cooling effect via the flexocaloric effect. A theoretical analysis based on the phenomenological thermodynamic theory of caloric effects is performed. The entropy and temperature changes (adiabatic) are derived by including flexoelectricity-induced polarization in Maxwell’s relation for the electrocaloric effect. An average temperature change of 1.82 K was achieved under an applied pressure of 100 MPa, which is not possible in conventionally used homogeneous trapezoid samples. The flexocaloric effect is observed to increase sharply with increasing load due to quadratic proportionality of temperature change with strain gradient. Further, the material composition can be tailored for increased entropy and temperature change by omitting the pure BST and PVDF phases at the top and bottom.