The Off-Axis IBII Test for Composites

Abstract

Composite components regularly experience dynamic loads in service. Despite this, it is still difficult to obtain accurate mechanical properties of composite materials under high strain rate conditions. In this study, a new application of the Image-Based Inertial Impact (IBII) test methodology was developed, to generate an accurate in-plane transverse and shear moduli dataset from unidirectional (UD) off-axis composite specimens. The obtained dataset was consistent across different sample configurations, where results from the UD45∘ off-axis specimens agreed well with the UD90∘ values. Validation of the shear modulus identification was also undertaken by comparing the results from the UD90∘ and UD45∘ specimens with a multi-directional (MD) configuration. Here, it was found that MD±45∘ specimen shear modulus values where marginally lower than that from the UD specimens, in accordance with the lower fibre volume fraction of the MD laminate. Low strain rate sensitivities in the 0.5 - 2 × 103 s - 1 regime evidenced in this work suggest previously published data (often from split-Hopkinson bar tests) may include both a material and system i.e. testing apparatus response.