High temperature in situ impact testing of hybrid thermoplastic polyether ether ketone laminates

Abstract

In order to evaluate the severity of thermal degradation on the impact response of carbon (C) and glass (G) fibers reinforced polyether ether ketone laminates, low velocity impact tests have been conducted at a temperature higher than the glass transition temperature (150°C). An instrumented Charpy pendulum (CP) equipped with a heating device was specifically designed to estimate its capability to perform low velocity impact tests at high temperature. The first important effect resulting from temperature increase is a reduction of the impact energy required to induce the barely visible impact damage (BVID), whose role is utmost important regarding the damage tolerance. The second effect is that temperature has also a tremendous influence on the internal damage as there is virtually no delamination at high temperature for impact energies. Finally, compared with the impact behaviors observed with the same laminates impacted with a drop tower and quasi‐static indentation, the impact velocity is about 2.5–3 times as low during CP impacts. As a result, slow loading rates are instrumental in increasing both the dissipated energies and the permanent indentation (PI) values (1.6–2 times as high) that are always higher than the BVID. Ultimately, as higher PI is usually correlated to higher impact damage tolerance.