ASM Failure Analysis Case Histories: Failure Modes and Mechanisms
A graphite-epoxy tapered-box structure, which consisted of two honeycomb skin panels fastened to a spanwise spar with intermediate chordwise ribs, fractured during testing. Hinge-line deflection of the front spar was revealed. Through-thickness cracks in the forward and trailing edges of the compression-loading skin panel were revealed by nondestructive visual examination. A band of de-lamination between the areas of through-thickness skin fracture at the front and rear spar was revealed. A map of the local directions of crack propagation over the fracture surface was generated by the orientation of river patterns and resin microflow during microscopic examination of sectioned samples of the panel. It was discovered that crack initiation occurred at the periphery of a fastener hole located at the front spar. Propagation occurred chordwise across the compression-loaded skin panel. As a corrective measure, the fastener spacing was reduced to prevent the buckling mode that precipitated fracture.
Distortion (Deformation), ASM Failure Analysis Case Histories: Failure Modes and Mechanisms, ASM International, 2019
Download citation file:
New Handbook: Volume 11B
Volume 11B serves as a reference and guide to help engineers determine the causes of failure in plastic components and make corrective adjustments through design and manufacturing modifications.