Geometrically nonlinear impact response of thin laminated imperfect cylindrical panels

Abstract

Although a large number of studies dealing with the impact response of flat laminated panels has been conducted in the past, relatively little work seems to be available on impact of laminated cyclindrical panels. In this paper an analytical study is conducted to predict the nonlinear transient response of thin imperfect laminated cylindrical panels subjected to impact loads. A review is also given regarding the state of the art on the impact response of laminated plates and shells. The imperfect panels are modeled using a 48 degree-of-freedom (DOF) finite element based on the classical laminated plate theory. Linear and nonlinear transient responses are obtained using the modal superposition method (MSM) and a reduction method based on Ritz vectors (R-R), both in conjunction with direct integration schemes (Wilson- θ or Newmark methods). The effect of the number of modes used is also discussed. A modified contact law is incorporated to evaluate the impact loads due to a projectile. Different nondimensional shell radii [ r/h] are used in order to study the effect of nondimensional shell radii [ r/h] on the impact response of laminated cylindrical panels. The effect of geometric imperfections on linear and nonlinear transient response under sudden impact loads is also analyzed. Both the MSM and R-R methods used in the analysis are found to have acceptable accuracy and the accuracy increased with the number of modes used. It is observed that the reduction of the nondimensional shell radius [ r/h] causes significant changes in the impact response of the cylindrical panel: a significant decrease in the central deflection and contact force histories. The introduction of geometric imperfections led to similar conclusions.