The use of quasi-static testing to obtain the low-velocity impact damage resistance of marine GRP laminates

The use of more economical quasi-static testing to predict the dynamic impact behaviour of marine GRP composites has been evaluated by comparing equivalent impact and quasi-static test results. Static tests predicted well the initial impact behaviour and onset of delamination damage, which is likely to be the key impact resistance design variable. However, only very conservative estimates of the final fibre failure and total energy absorption capacity were achieved, except for the thickest specimens where fibre damage occurred at similar loads for both static and impact tests. Quasi-static testing avoided the problems associated with oscillations in the force signal, and delamination force showed a very strong linear relationship with laminate thickness3/2 as predicted by two simplified models. It was inferred that the undamaged and delaminated responses are not strain rate dependant, but that the fibre failure mechanisms are.