A model for rod ricochet

A model to predict the ballistic ricochet of rod penetrators is presented. The model is based on the premise that the phenomenology of ricochet is one where the impacting rod feeds into a plastic hinge located at the rod/target interface, and is thus diverted from a penetrating trajectory. The model is offered in both a full and simple form. The full form of the model arises from the simultaneous solution of a series of six algebraic equations that constitute the momentum-flux/force and moment balances upon the plastic hinge, subject to various material and kinematic constraints. This full model is not solvable in closed form, but rather by way of algorithm. The simple form of the model, by contrast, dispenses with the moment balance and makes several simplifying kinematic assumptions that permit the ricochet criterion to be expressed as a closed-form inequality. Such a simplified form is along the lines of, and thus directly comparable to, several prior ricochet models in the literature. Compared against 24 ballistic tests, comprising two separate ricochet studies, the current model (in both forms) shows an improved ability to predict the ballistic ricochet of impacting rod projectiles. The simple form of the current ricochet model actually proved the best predictor of the ballistic data.