Influence of impact compressive load on laminated composite strength

High and low velocity impact responses of glass/epoxy laminates were investigated. Six laminate plates having 16 identical layers with different stacking sequence are used. Influences of stacking sequence on the composite compressive strength as well as the failure surfaces are revealed. Results show that the 45 plies must be dispersed between 0 plies and 90 plies to have a maximum strength level. The 45 and 90 plies stacked together show a matrix cracking with low level of composite strength while the 0 plies demonstrate clearly the delamination mode and consequently the splaying of fibers occurred. In the same manner, the mechanical behaviors of a unidirectional glass/epoxy lamina under high and low impact velocity are determined. The influences of fiber orientation on the composite strength and failure modes are discussed. A transverse tensile failure mode appeared due to longitudinal compressive load. A split Hopkinson pressure bar (SHPB) apparatus is used to perform this study at room temperature.