High strain rate elasto-plasticity identification using the image-based inertial impact (IBII) test part 1: Error quantification

Current high strain rate testing procedures generally rely on the split Hopkinson bar (SHB). In order to gain accurate material data with this technique, it is necessary to assume the test sample is in a state of quasi-static equilibrium so that inertial effects can be neglected. During the early portion of an SHB test, it is difficult to satisfy this assumption making it challenging to investigate the elastic-plastic transition for metals. With the development of ultra-high speed imaging technology, the image-based inertial impact (IBII) test has emerged as an alternative to the SHB. This technique uses full-field measurements coupled with the virtual fields method to identify material properties without requiring the assumption of quasi-static equilibrium. The purpose of this work is to develop the IBII method for the identification of elasto-plasticity in metals. In this paper (part 1), the focus is on using synthetic image deformation simulations to analyse identification errors for two plasticity models, a simple linear hardening model and a modified Voce model. Additionally, two types of virtual fields are investigated, a simple rigid body virtual field and the recently developed sensitivity-based virtual fields. The results of these simulations are then used to select optimal processing parameters for the experimental data analysed in part 2.

Automated summary

The assumption of quasi-static equilibrium is crucial for obtaining accurate data in split Hopkinson bar testing. Image-based inertial impact (IBII) testing has emerged as an alternative that does not require this assumption, utilizing virtual fields for material property identification. The aim of the study is to develop the IBII method for identifying elasto-plasticity in metals.