Physical interaction effects of out of plane waviness and impact damages of fiber composite structures

Kurzfassung

This thesis provides the experimental investigations for an improved physical understanding of the interaction behavior between out of plane waviness (OoP) and low velocity impact damages. Plain strength compression (PSC), impact as well as compression after impact (CAI) tests on the compression strength of a quasi-isotropic laminates were conducted. The effects of OoP waviness and impact damages were considered separately and simultaneously. In the PSC case, two thicknesses with different waviness configurations were tested in order to identify the critical waviness parameters and their dependence on the thickness. A corresponding pure waviness Knock-Down-Factor (KDF) was derived. In the CAI case, one thickness with different waviness configurations as well as one configuration without waviness were tested. The CAI tests with and without waviness led to the derivation of three KDFs. The experimental results reveal that the waviness effect in the investigated impact energy level is present, even if the corresponding KDF is not always degraded. Waviness effects cannot compensate impact effects or vice versa, accordingly, the interaction behavior represents approximately a multiplicative relation which can be simplified by superposition of both effects individually.