Composite materials, typically consisting of two or more dissimilar materials adhered together in layers, are frequently used for energy absorption applications. The interface and material characteristics strongly influence the global energy absorptive capability of the composite. This research focuses on ceramic-polymer interfaces and, in particular, links between the properties of the composite, the interface and the separate materials. After characterisation of the materials, the effects of impact speed and bond condition were considered for a polymer-ceramic bond in a threepoint bend configuration. Specimens were loaded in a screw-driven machine at 0.05 mm s-1 and through projectile impact at speeds of approximately 50 m s-1. Screw-driven experiments were performed at ambient and sub ambient conditions, with the temperature chosen to simulate the expected polymer performance in the gas gun experiment, making use of the equivalence of rate and temperature for polymers.
Polymers possess a wide range of mechanical behaviours depending upon the temperature and loading rate. An often-overlooked aspect is relaxation, important because it acts over a wide range of time periods and begins as soon as the polymer is loaded. In the research presented, the relaxation behaviour of two polyurethanes (PUs) following deformation was investigated at low-rate, 10
−3
s
−1
, and dynamic, 10
3
s
− 1
, loading rates, with the former exploring temperatures from 20°C to −60°C. These are compared to a predictive Prony series model calibrated using mastercurves produced by applying time-temperature superposition to data obtained using a dynamic mechanical analysis machine. For relaxation after dynamic loading, a recently proposed analysis was used to account for the movement of the bars during relaxation. The model could predict the stress-time response after low-rate deformation to strains of 2%, at all temperatures. As the strains increased, irrecoverable deformation was observed and the model became less accurate. In the dynamic experiments, the model accurately predicted the early stages of relaxation for both PUs but deviated later on. A modification was suggested to account for these observations. Further characterization of the mechanical response under large strain compressive loading is also reported.
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