Transient dynamic analysis of laminated composite plates subjected to transverse impact

A transient dynamic finite element analysis is presented for studying the response of laminated composite plates due to transverse foreign object impact. The analysis can be used to calculate displacements of composite plate during impact and the transient stress and strain distributions through the laminate thickness. An 8-point brick element with incompatible modes was developed in the analysis, and the direct Gauss quadrature integration scheme was used through the element thickness to account for the change in material properties from layer to layer within the element. The Newmark scheme was adopted to perform time integration from step to step. A contact law incorporated with the Newton-Raphson method was applied to calculate the contact force during impact. A computer code was developed based on the analysis. The results of calculations from the code were compared with the existing analytical solutions. An excellent agreement was found between the comparisons. Numerical solutions for selected problems were also generated. The effect of the initial velocity of the impactor on the contact force distribution, the displacements, and the transient stress and strain histories inside the plate during impact were studied. In addition, the strain energy density distributions in the plate as a function of time were also calculated for different ply orientations. It seemed to indicate that a correlation between the strain energy density distribution and impact damage existed.