Application of Full-Field Measurements to Analyse the Thermo-Mechanical Response of a Three-Branch Rubber Specimen

Abstract

The study deals with the characterization of the thermomechanical behavior of rubber. A test performed on a three-branch-shaped rubber specimen is used for this purpose. This heterogeneous test simultaneously induces the three types of stretch states classically considered to identify mechanical properties of rubber (uniaxial and equibiaxial tension, and pure shear), as well as the intermediary states. Recent works in which such heterogeneous tests are studied only consider the deformation field, but neither the corresponding thermal field nor the heat sources field are taken into account. The aim of the present study is to push forward the idea of heterogeneous tests by measuring both the displacement and thermal fields on the specimen. During the experiments, the displacement and thermal fields are measured using cameras. Measurements are then processed to associate a temperature and a strain level to each material point using a motion compensation procedure. The heat source fields are then derived from the temperature maps. Indeed heat source appears to be more relevant than temperature for characterizing the thermomechanical response of materials. Results obtained during the experiments will be presented in this paper. A discussion will also be initiated on the influence of the loading conditions on the heat source maps.