Numerical and Experimental Studies of Damage Generation in Multi-Layer Composite Materials at High Strain Rates

摘要

This report concerns the results of a S.T.I.R. Program carried out between March and November 2005. The general objectives of the program were to demonstrate the feasibility and utility of a novel use of the Split Hopkinson Pressure Bar (SHPB) as a tool for the investigation and development of multi- layered materials for high strain rate applications. Here, the SHPB is not used as a device for generating mechanical property data but is, instead, used as a probe to generate input and output signals which are then used to validate numerical models. The principle of the method is to perform an experiment on the SHPB and collect the usual data which accurately define the input wave and the exit waves. Strain gages on the sample itself can provide extra data at specific locations on the sample surface. The numerical model is then developed, based on properties from tests conducted on simple single layer samples. The model comprises the incident and transmitter bars of the SHPB set-up plus the sample: the known incident wave is the model input. Then, when the numerically calculated exit waves exactly match the experimentally determined exit waves the model must be accurately capturing the details of wave propagation, transmission and reflection within the sample itself. This provides the basic validation of the model.