An analysis of impact force in plain-weave glass/epoxy composite plates subjected to transverse impact

In the present study, a new analytical method is developed for predicting the impact force from the dynamic strain of composite plates subjected to transverse impact. For this, two assumptions are introduced in this study. Firstly, the impact force and dynamic strain can be separated into frequency and amplitude. Secondly, the amplitude of the impact force corresponds to that of the dynamic strain at any frequency. By applying the Rayleigh–Ritz energy method and Lagrange’s principle to a rectangular plate, the governing equation is derived, and the equation is solved by an optimal design technique. To verify this analytical method, impact tests are performed on plain-weave glass/epoxy composite plates having various thicknesses. The impact forces obtained by this analytical method agree well with the experimental results for all plate thicknesses studied. Additionally, the dynamic response, such as the impact force, is greatly influenced by the thickness. This behavior is attributed to the different energy absorbing mechanisms: the absorbed energy is governed by the plate deflection in a thin plate, whereas the energy is governed by the local indention in a thick plate.