Analysis of Low Velocity Impact on Pultruded Fiber Reinforced Polymer Plates

Abstract

Impact is one of the greatest design limitations involved in designing new composite products. The purpose of this research was to gain an initial understanding of the impact behavior of fiberglass reinforced pultruded laminates with vinylester and isopolyester resins. The effect of adding a protective layer of rubber to the laminates was also investigated.

Several drop tower impact test were performed with a relatively high mass (12 lbs.) and a low velocity (80-150 in/s). These impacts produced severe damage in some of the laminates with only one impact. The 3D stitched laminates and the Duraspan™ laminates, which are used in Martin Marietta Composite's bridge decks, showed the least amount of visible damage of the laminates tested. The Duraspan™ laminates however, had two interlaminar delamination regions while the others only had one. This delamination was seen with C-san images of the impacted laminates. This extra delamination region did not decrease the tensile strength at all. Tensile tests were performed with a 1 in. strip from the center of the impacted samples in order to test the residual tensile strength.

Finite element models were created with ANSYS/ls-Dyna nonlinear finite element software. These models were used to simulate the drop tower tests and then were extended to thicker laminates as well as different impact speed and impactor mass. Several models were also created to predict the effects of the rubber protective layer.

These models were able to predict approximate stresses and strains induced in the laminates during the impact which were 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.