Moisture Gradient Considerations in Environmental Fatigue of CFRP

Abstract

The evolution of the techniques of conditioning composite material in the laboratory to simulate in service degradation is briefly summarized. The development of environmental fatigue programs, involving simultaneous loading and environmental cycling is seen as introducing new problems, par ticularly if acceleration of ground dwell leads to input frequencies which dif fer from real life values. The frequency effect is illustrated by theoretical ex amples which attempt to evaluate and compare the moisture gradients in duced by an environmental fatigue regime and a typical aircraft outdoor en vironment.

The theoretical method used in this paper would appear to be of general applicability in assessing the realism of accelerated conditioning and testing of CFRP specimens.

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