Experimentally Simulating High Rate Composite Deformation in Tension and Compression: Polymer Bonded Explosive Simulant

Abstract

Characterizing the response of composite materials to high strain rate deformation is of great importance for a range of applications; however, the experiments required to do this are challenging. In order to be fully representative, specimens must be large, making it difficult to achieve mechanical equilibrium; furthermore diagnostic tools such as X-ray tomography and electron microscopy cannot be used on the required timescales of ca 10 μs. Many composites consist of a rate and temperature dependent polymer binder, with a filler that is independent of these parameters. In this paper, a simulation technique is applied, in which the high rate mechanical response of a composite is experimentally reproduced in low strain rate experiments by making use of the polymer time–temperature superposition principle. This is a novel application of time–temperature superposition to composite materials in order to experimentally replicate the high-rate response. In order to demonstrate this method on a model composite material, a particulate composite (polymer bonded sugar) and its binder are extensively characterized in compression, and the composite in indirect tension (Brazilian) tests, over a range of strain rates and temperatures. It is then shown that by reducing the temperature, low rate experiments can be performed which faithfully replicate the high rate data, opening up the opportunity for more extensive research programs combining mechanical testing and microstructural characterization of these materials.