An approximate theoretical procedure based on a rigid plastic method is developed to give the lower and upper bounds of the dynamic plastic solution to the impacted rectangular plate with finite deflections. The analytical solution obtained is compared with the experimental results and predictions of a numerical program developed by the senior author, in which elasto-plastic workhardening material can be adopted. The analytical solution provides formulae which can be used for the design of fully clamped plates against impact, and provides information on maximum deflection, impact duration and maximum impact force. The design formulae are expressed as a function of geometry and material properties of the struck plate, mass and impact velocity of the striking object. The effect of other boundary conditions is also discussed.
The rectangular plate is a widely used structural type in ships and marine vessels which often suffers from dynamic loads such as slamming collision and grounding. If the dynamic loads are large enough to cause severe deformation of the plates then the response of a structure can be studied with the aid of plasticity theory [Jones, 1972]. Lee and Symonds [1952] were the first to use the rigid perfectly plastic method to predict the inelastic response of beams under dynamic loads. In using the rigid perfectly plastic method, it is usually assumed that elastic effects may be neglected when the dynamic energy is at least three times larger than the maximum elastic stream energy capacity and that the pulse duration is smaller than the fundamental period of the structure. For rectangular plates because of the difficulties arising from the complication of the generalized stresses it is almost impossible to obtain the exact solution for the dynamic response of the rectangular plate at finite deflections.
