Defence Science lournal, Vol. 53, No. 1, January 2003, pp. 15-24 O 2003, DESIDOC On the Mass Impact Loading of Ductile Plates* Norman Jones university of Liverpool, Liverpool L69 3GH. UK ABSTRACT This paper examines the response of circular and square plates stluck by a rigid mass at the plate centre with a sufficient initial kinetic energy to produce large inelastic deformations. A simpliiicd analysis, which retains finite-deflection effects and assumes that the plates are made of a rigid, perfectly plastic material, provides a relatively simple theoretical solution for the maximum permanent Inusvet:;: displacement and the response duration. It transpires that the theoretical predictions give reasonable agreement with the maximum v e n t transverse displacements recorded in several experimental studies on fully clamped, circular and square ductile metal plates. The final theoretical expressions for the behaviour are easy to use and ideal for preliminary design purposes and would be sufficiently accurate for final designs in some applications. Keywwds: Impact, square plate,-circular plate, ductile deformations, theoretical analysis, large deformations NOMENCLATURE N Membrane force (per unit length) a Radius of rigid striker No aoH. Full plastic collapse force of a solid cross-section (per unit length) rn Bending resistance factor at supports N,,N, Radial and circumferential membrane forces w Transverse displacement (per unit length), respectively E Young's modulus of elasticity E , Energy ratio G Striker mass H Plate thickness Q, Transverse shear force (per unit length) R Plate radius T Duration of response vo Impact velocity 2L Length of a square plate W,W, Maximum and permanent transverse M Bending moment (per unit length) displacements, respectively Y Mass ratio Mo 00H.!14. Full plastic collapse moment of a solid cross-section of a plate (per unit length) c.6 Strain and strain rate, respectively M*,M, Radial and circumferential bending moments K,, K, Radial and circumferential changes of . - (per unit length), respectively curvature, respectively - Received 24 October 2002 * Dedicated to Professor Narinder K Guptd on his 60'"inhday 15