Low velocity impact damage characteristics of Z-fiber reinforced sandwich panels - an experimental study

Experimental results related to the initiation of damage in Z-fiber truss-reinforced sandwich panels are presented. Two different orientations of Fin angles are considered. A pendulum-type impactor is used to impart very low levels of impact energy. Threshold energy levels at which the observable damage initiation occurs are determined. Nondestructive evaluation studies conducted prior to the impact are compared with the post-impact status of the panels for assessing the type and magnitude of the damage. These studies include ultrasonic inspection, microscopic inspection and acoustic emission tests. Damage is also evaluated by carrying out vibration tests before and after impact. Static indentation tests are carried out to compare with low velocity impact tests. Effects specific to the impact phenomena are studied by comparing the load displacement characteristics. Compression after impact characteristics are also evaluated. (C) 1999 Elsevier Science Ltd. All rights reserved.