Combined effects of end-shortening strain, lateral pressure load and initial imperfection on ultimate strength of laminates: nonlinear plate theory

  • Ghannadpour, S.A.M. (New Technologies and Engineering Department, Shahid Beheshti University) ;
  • Barvaj, A. Kurkaani (New Technologies and Engineering Department, Shahid Beheshti University)
  • Received : 2019.05.03
  • Accepted : 2019.10.02
  • Published : 2019.10.25


The present study aims to investigate the ultimate strength and geometric nonlinear behavior of composite plates containing initial imperfection subjected to combined end-shortening strain and lateral pressure loading by using a semi-analytical method. In this study, the first order shear deformation plate theory is considered with the assumption of large deflections. Regarding in-plane boundary conditions, two adjacent edges of the laminates are completely held while the two others can move straightly. The formulations are based on the concept of the principle of minimum potential energy and Newton-Raphson technique is employed to solve the nonlinear set of algebraic equations. In addition, Hashin failure criteria are selected to predict the failures. Further, two distinct models are assumed to reduce the mechanical properties of the failure location, complete ply degradation model, and ply region degradation model. Degrading the material properties is assumed to be instantaneous. Finally, laminates having a wide range of thicknesses and initial geometric imperfections with different intensities of pressure load are analyzed and discuss how the ultimate strength of the plates changes.


ultimate strength;geometric nonlinearity;lateral pressure;initial imperfection;Ritz method;Hashin criteria