Analysis of Equibiaxial Tension Tests for Hyperelastic EAP Film

Abstract Equibiaxial tension tests for hyperelastic electroactive polymers (EAPs) are important means to obtain the mechanical properties. There are three main methods: equibiaxial planar tension, radial tension and bulge test. The finite element analysis software is used to model and analyze the influence of testing apparatus, specimen geometric parameters on the test results and accuracy. The results show that the uniformity of the deformation of the square film can be effectively improved by using single corner point fixed tension in equibiaxial planar tension test, and the force error also decreased; the number of the cuts and the size of punched holes should be appropriate in radial tension test of circular diaphragm specimen to avoid the material strength failure caused by excessive tension along the edge of transition arc between grips and excessive deformation of tensile belt between the cuts; in bulge test, the sampled deformation data should be near the spherical pole to obtain more accurate stress-strain relationship owing to contour error and non-uniform deformation, a certain range of model parameters will limit the scope of simulation analysis. This paper proposed research provides guidance for the design of equibiaxial tension test apparatus and method to obtain more accurate test results.