The Residual Strength of Cracked Specimens Representing a Section of the Mirage IIIO Wing Main Spar.
Abstract
The discovery of fatique cracks at bolt holes in the wing main spar of many RAAF Mirage IIIO aircraft prompted an investigation into the residual strength of cracked specimens representing the critical section of the spar. Fatique cracks were grown at the bolt holes of the specimens, which were frequently inspected to monitor the crack length. The specimens were then broken in static tension, the fracture surfaces photographed and the lengths, depths and areas of the fatique cracks measured. Using only the data available from the non-destructive inspection made just prior to the static failure it was not possible to predict accurately the specimen residual strength though it was possible to estimate a lower bound. Crack lengths, as estimated by the NDI technique used, were close to the measured crack lengths, though usually greater. Using the measured crack lengths, depths and areas it was no possible to predict accurately specimen residual strengths, though results were better than if information obtained only by NDI were used. Fracture mechanics techniques could not be used to predict residual strengths because of a lack of suitable Stress Intensity factor solutions. Additional keywords: Australia; fracture strength; aluminum; eddy currents; fatique life.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 01, 1984
- Accession Number
- ADA153615
Entities
People
- A. S. Machin