Simulation of precise setforward and setback experiments

The issue of setback and setforward in gun and penetrator systems is potentially very serious given the drive toward new compositions and higher velocities. The only means of assessing this risk in the real system is through simulations and small-scale testing, since onboard instrumentation is not straightforward and is limited in the data generated. However, for this approach to be successful it is important to validate the models used in the simulations to obtain the necessary degree of confidence. This demands the design of experiments coupled with precise instrumentation to replicate the forces observed in the real system. Precise setback and setforward experiments have been performed aimed at providing validation data and understanding the processes involved and both indicating that little slippage of the filling has occurred. The experiments have been simulated using the QinetiQ GRIM hydrocode using a semi-empirical interim model for the visco-elastic filling material. The results are discussed and future studies are outlined.