DYNAMIC DELAMINATION CRACK PROPAGATION IN A GRAPHITE/EPOXY LAMINATE (COMPOSITE MATERIALS, IMPACT, FRACTURE)
Abstract
Impact tests of 90/0 (,5s) T-300/934 graphite/epoxy laminates of beam-like dimension with embedded delamination cracks were conducted. High speed photography (16000 frames/sec) was used to record the impact response and subsequent crack propagation. From the photographic data, impact characteristics such as the contact duration and the dynamic response of the impact specimen were measured. In addition, the time of initiation of crack propagation and measurements of the subsequent crack length versus time were obtained. By changing the location of the embedded delamination in the specimens relative to the impact point, additional results were obtained on the variation of the threshold impact velocity necessary to cause crack propagation in the different specimen configurations. A further series of impact tests with instrumented targets was used to characterize the dynamic force history resulting from the high speed impact of a rubber ball. A finite element analysis was performed to calculate the dynamic strain energy release rate prior to the onset of delamination. The critical value of the strain energy release rate necessary to initiate propagation of a delamination in this material was investigated.
Degree
Ph.D.
Subject Area
Aerospace materials
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