Primary aerospace composite structures are often joined by bolted joints dueto its capability in transferring high loads and ease in disassembling and assemblingfor inspections and repairs. Joint strength in composites can be significantlyreduced with operational use beyond originally intended design life due to theaccumulation of internal damage which necessitates more frequent inspections.Internal damage (delamination, matrix cracks) can continue to propagate withoutbeing seen through visual inspections, thus nondestructive testing is required.However, this may be costly, particularly for a full-scale aircraft. Thus, acomprehensive understanding of joint damage growth behavior is necessary toguide what damage modes to inspect for as well as the frequency of inspection. Inthis work, an experimental investigation was performed on single-countersunkbolted-joint specimens and semi-circular through-hole and countersunk holespecimens under static load to study the effect of pin bending on bearing damage(i.e. shear cracks). The static tests results were compared to cyclic loadedspecimens from previous published work to develop a greater understanding of therelationship between hole elongation and damage growth in a double lap shear testconfiguration [1]. The static test results indicate pin bending did not contribute tothe bearing failure. Shear crack formation at the shank was found to be caused bythe compression-induced instability of fibers (fiber kinking) near the free surface ofthe laminate.
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