Investigations of Laminated FRP Composites for Low Velocity Impacts

Fibre reinforced composites have become increasingly important over the past few years and are now the first choice for fabricating structures where low weight in combination with high strength and stiffness are required. Many of the new and innovative products are influenced by impact damage, whether by design or by accident. Impact properties such as damage resistance are crucial to product design. The present work is aimed at gaining an initial understanding of the impact behavior of fiberglass reinforced laminates with vinylester and isopolyester resins. The purpose of this research is to characterize the damage done to fiberglass laminates subjected to low velocity, high mass impact. The effect of adding a protective layer of rubber to the laminates is also investigated. Finite element models are created with ANSYS/Ls-Dyna nonlinear finite element software. These models are used to simulate the drop tower tests and extended to thicker laminates as well as different impact speeds and impact or mass. Several models are also created to predict the effects of the rubber protective layer. Several drop tower impact test were performed with a relatively high mass (5.5 kgs.) and a low velocity (2-4 m/s). These impacts produced severe damage in some of the laminates with only one impact. These models are able to predict approximate stresses and strains induced in the laminates during the impact which are compared to the damage from the drop tower tests. The models predicted that the rubber layer decreased the stress and strain in the laminate up to 50%. The drop tower tests confirmed that the rubber aided the impact resistance significantly.