SEDL / STP / STP797-EB / STP28544S

Effect of Microstructure on the Mechanical Behavior of Sheet Molding Compound Composites

Kline, RA
Senior Research Engineer, Engineering Mechanics Department, General Motors Research Laboratories, Warren, Mich

Pages: 24    Published: Jan 1983

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Abstract

Mechanisms for damage initiation and growth in sheet molding compound composites were studied with several nondestructive testing techniques. Damage was found to initiate by matrix cracking at relatively low stress levels. Fiber bundles were found to be effective in impeding the progress of these matrix cracks. At higher stress levels, however, the fiber bundles can no longer resist matrix crack propagation and specimen fracture occurs principally by fiber-matrix debonding. Specimen inhomogeneity was found to play an important role in these materials, with large variability in local fiber content being observed. Resin-rich regions of the specimens were identified as being likely failure sites.