Polymer Matrix Composite (PMC) Damage Tolerance and Repair Technology.

摘要

The application of composites in space structures such as reusable launch vehicles requires a detailed understanding of their mechanical behavior and damage resistance in the service environment. Experimental and analytical studies were conducted on IM7/977-3, a graphite-toughened epoxy, to characterize the influence of cryogenic service temperatures on the strength, modulus, and fracture of this material system, and on transverse crack initiation in cross- ply laminates at 23, -129, and -196 deg C. Transverse tensile and shear strengths and moduli increased at the cryogenic test temperatures while strain to failure decreased, denoting increased brittleness. The stress for the onset of transverse cracking decreased substantially at cryogenic temperatures, due primarily to an increase in the curing residual stresses. Laminated plate theory, in conjunction with maximum stress criteria, appears to overestimate the onset of the transverse cracking in this laminate.