Evaluation of impact damage in nonlinear laminates subjected to a transverse concentrated load

Nonlinear response of multiply delaminated plates subjected to a transverse concentrated load is approximately solved to estimate significance of impact damage of composite laminates. The size of damage is given as a function of the impact energy, dimensions of the plates and the material properties such as interlaminar toughness of the laminates based on the expression. The damaged portion is modelled as equally spaced multiply delaminated plates as shown in the figure below. A superposition technique is used on the problem to derive an approximated solution. The one problem is a basic problem that a plate is subjected to a concentrated load at its center. The shape of the plate must not be circular. The intact plate can be lightly nonlinear. The other is a problem that a thin circular plate with the radius and the thickness of the ligaments of the multiply delaminated portion. The edge of the delaminated plate is assumed to be fixed at its periphery. The applied load is assumed to be equal to the bending stiffness loss by the introduction of the multiple delaminations. The results obtained from the present theory agree excellently with finite element results and explains well the experimental results.