Experimental and numerical analysis of low-velocity impact of plastic laminates

Acrylic is extensively used in transparent laminate systems with glass, polycarbonate, polyurethane and other polymers. Impact response of laminated structures is a subject of critical interest because of the high probability of impacts occurring during the manufacture, service or maintenance of structures. The impact loading induces a complex interaction between structural and material behaviour. Impact tests have proven inherently difficult to characterize because of the large number of parameters that play a key role in structural behaviour. Evaluation of impact in the case of ballistic tests is usually in terms of the minimum energy required to cause complete penetration or the maximum energy before penetration. So, metrics like V-100 ballistic limit and V-50 ballistic limit are determined from a series of experiments. However, in low-velocity impacts, these statistical estimates are not appropriate. Furthermore, they do not indicate the failure mechanisms involved, the understanding of which is necessary to select materials for improved impact resistance. Different parameters are required to indicate the severity of the event and provide an understanding of the low-velocity impact behaviour. This paper deals with applying a multi-parameter approach to evaluate the low-velocity impact on circular plates of acrylic. The work presented herein focuses on developing a numerical model to simulate the impact deformation and failure behaviour of brittle polymeric materials such as acrylic. The numerical model was developed using the commercial finite element analysis software ls-dyna, and the results of the simulation is compared with the experimental results obtained from drop tower tests. The dynamic force histories and damage patterns obtained from the finite element simulation show good agreement with the experimental data from drop tower impact tests.