Temperature- and rate-dependent tensile behaviour of unidirectional carbon/polyamide-6 composite under off-axis loading with oblique tabs

Abstract

Unidirectional carbon/polyamide-6 (CPA6) is a thermoplastic composite with attractive properties for many industrial applications. However, shortage of experimental data may hinder the development of reliable material models. This paper is the first to provide a complete dataset for the tensile behaviour of unidirectional CPA6, including the longitudinal, transverse, in-plane shear, and off-axis response, at different temperatures and (quasi-static) strain rates. The oblique end tab design, already proven in the literature for off-axis testing of composites at room temperature, was successfully extended to the elevated temperature of 120 °C. The use of cardboard tabs and fast-curing adhesive greatly simplified the tab manufacturing and application for all the combinations of fibre angles, temperatures and strain rates. Digital image correlation (DIC) was performed through the window of the temperature chamber to verify the homogeneous strain field produced by the oblique tabs. The in-plane shear behaviour was extracted from the off-axis tests, allowing to estimate the shear modulus and shear strength. Finally, the robustness of the experimental results generated in this study was demonstrated with well-established analytical models that could excellently predict the elastic modulus, Poisson’s ratio, and failure stress at different fibre angles.