The use of experimentally-determined impact force as a damage measure in impact damage resistance and tolerance of composite structures

An instrumented drop-weight impact rig, ultrasonic C-scan and CAI test rig form a basic experimental system needed for the quantitative investigation of impact damage resistance and damage tolerance assessment. It is shown th at it is essential to have an impact rig designed with certain traits along with other selected impact conditions so that dominant damage mechanisms o ccurring during impact can be identified with the threshold forces of recor ded impact force-time curves. The so-determined impact force data are used to study impact damage resistance. It is demonstrated that the ratio of mea sured threshold impact forces is a useful alternative to residual compressi ve strength usually used for damage tolerance assessment. This provides a f ast and cheap technique without resort to complex and expensive CAI tests. (C) 1998 Elsevier Science Ltd. All rights reserved.