Low-Velocity Impact and Damage Process of Composite Laminates

Abstract

Several important issues regarding damage simulation of composite laminates due to low velocity impact were investigated including contact law, damage initiation and the corresponding change of stiffness, and damping. Continuum damage mechanics was applied to account for the change of mechanical properties of damaged materials. The Hertzian contact law was modified in order to accommodate the serious damage in the plate. A semi-empirical delamination damage criterion was introduced. A finite element program was written in FORTRAN using twenty-noded solid elements with layered structure to analyze the transient dynamic response of composite laminates. In the simulation computations, variable material damping coefficients were applied to the elements according to damage in order to stabilize the computation. Damage in the forms of matrix cracking, delamination, and fiber breakage were included and analyzed. Results including the force history and delamination areas were found to correlate well with the experiments.

Evaluation of Force-Time Changes During Impact of Hybrid Laminates Made of Titanium and Fibrous Composite

“…1) and often considered as composites resistance to impacts. As indicated by Guan et al [14] and by Bienias et al [7], further oscillations of force in this stage may result in the occurrence of next local structural damages or in development of already occurred matrix damages. However continuous growth of force suggests that the material is still capable to carry the loads associated with impact and to absorb the energy transferred by the impactor.…”

“…1). The first visible disturbance of force is interpreted as the damage initiation moment in composite [14]. In many scientific studies e.g.…”

“…In many scientific studies e.g. [12,13,14], the authors suggest that it is the damage initiation moment in polymer matrix which is the weakest component of composite in terms of strength and formability. The first damage initiation moment is defined as P i point ( Fig.…”

“…The force vs. time curves represent the information about the values of forces causing gradual degradation of material as well as about the intensity and scale of initiating and developing damages. The authors of studies [12,13,14] [12].…”

Behaviour of multiple composite plates subjected to ballistic impact

“…By this time, a number of studies have been carried out in this direction, but most of them are concerned with low velocity impact [9][10][11][12][13][14][15][16][17][18]. For high velocity impact, specifically for the range of impact considered in the present problem where the impactor penetrates the panel completely and exits with a residual velocity, the numbers of reported studies are very few.…”