Guillaume FISCHER
DOI Number: N/A
Conference number: HiSST-2025-197
Because high velocity means high temperature on airframes, ceramic matrix composites (CMCs) are often seen as very suitable materials for such application. Depending on the family of CMC, they can retain their mechanical properties up to 1000°C (typically oxide-based composites), 1600°C (carbon and silicon carbide-based composites) or even above 2000°C (ultra high temperature ceramic-based materials). The term thermostructural was originally designed for materials with such properties. Airframe parts are intrinsically exposed to any external environment of the vehicle. Having these parts made out of CMCs raises the question of their behaviour regarding these environments. Acceptable
effects of the environments are usually defined in a specification. Among the various effects that can be found in a specification, mechanical impact is a concern for CMCs. Low velocity impact damage can be associated to a falling tool, hail or projected pebbles. Coupons from an oxide-based CMCs were tested with different impact energies at low velocity. Similarly to organic matrix composites (OMCs) different regimes can be identified, based on the rate of absorbed energy. The extent of the internal damage, such as delamination, was also determined and correlated to the damage regime. Gathering the data that can be found in the scientific literature on low velocity impact of CMCs, as well as the
results from the aforementioned tests a comparison was drawn with OMCs. Common principles were interestingly raised but strong differences remained. The transitions between the damage regimes is lower by one order of magnitude for CMCs than OMCs.