Influence of thermal cycling on the low velocity impact response of CFRP laminates

Low velocity impact tests were carried out on unidirectional CFRP laminates previously aged with up to 80 thermal cycles between temperatures of -16 °C/+80 °C, in order to assess the effect of repeated temperature changes on the impact behavior of the material. The specimens subjected to the highest numbers of thermal cycles present a lower energy absorption during impact. In addition, the load drops that are usually visible in the contact force history of impacted laminates, and are attributed to the propagation of delamination, tend to disappear as the number of thermal cycles increases. On the other hand, both visual inspection and optical microscope analysis showed that no significant difference is induced by thermal cycling in the extent of delaminations. Thermal aging probably induced an embrittlement in the material, due to matrix microcracks that are generated at the lowest temperatures.