By the early 1980s, the y emphasis was shifting from development of composite materials to development of tough, durable composite materials. The common catch phrase that emerged was "effects of defects." This new emphasis on toughness dictated the development of test methods that could measure this material property. Defects can occur naturally during composite fabrication, and damage can be induced by impacts in service, but these tend to be relatively uncontrolled events. It was desired to induce an easily reproducible defect and, obviously, one reasonably representative of a service environment. This led to the tensile or compressive test of a specimen containing a carefully drilled hole. This method provides a controlled simulation of a natural defect in a composite structure, but can double as a method for testing fastener holes as well.
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