A METHOD FOR SCALING BALLISTIC PENETRATION PHENOMENA

There are several established formulae for projectile penetration into semi-infinite concrete targets. Most of them include a term which ind icates that regular scaling does not hold in this situation. Most of t hese formulae were derived using curve-fitting procedures, so that the se terms do not represent any physical meaning. Non-scaling is also fo und in long rod penetrations, which cannot be attributed to strain rat e effects. It is suggested here to differentiate the energy spent by t he projectile during the penetration process into two parts, one-the e nergy expended for surface effects and the other-the energy expended f or volume effects. By doing so, it is possible to derive expressions w hich account for the irregularity in scaling. These expressions are de rived from the global, energy balance point of view, so they do not re quire the detailed characterization of the materials involved. They on ly require strict adherence to replica scaling procedures. A similar a pproach is used to account for strain rate effects, but in that case, the results are not as general and can be applied only to a narrow spa n of configurations. Examples are cited from tests with concrete penet ration and long rod penetration into different targets. (C) 1997 Publi shed by Elsevier Science Ltd.