Identification of non-homogeneous stress fields in dynamic experiments with a non-parametric method

Stress and strain fields are generally assumed homogeneous in high strain rate experiments. Therefore, only mean stress and strain are measured. However, this assumption is not valid for soft materials and/or very high strain rates. For heterogeneous dynamic tests, inverse techniques are usually proposed to identify the stress and strain fields. In this paper, a non-parametric method to identify the stress field is presented. This method is based on a force measurement on the specimen boundary and a displacement (strain) field measurement carried out by a digital image correlation technique. It is applied to measure the strain rate sensitivity of a synthetic rubber (Criblex 80). This new technique estimates the stress field with good accuracy.