Improving the Fatigue Performance of Thick Aluminium Alloy Bolted Joints by Hole Cold-Expansion and the Use of Interference-Fit Steel Bushes
Abstract
Fatigue tests under a flight-by-flight loading sequence have been carried out on small bolted joint specimens of 23 mm thickness representing part of the spar rear flange/skin attachment in Mirage III aircraft. The investigation has shown that by cold-expanding the bolt holes to take standard oversize bolts, or by installing interference-fit bushes, the fatigue life can be more than doubled compared with the use of standard close-fit bolts in reamed holes. No significant differences were found between the fatigue lives of specimens embodying low-alloy steel or stainless steel bushes. When small-sized residual fatigue cracks are present, hole cold-expansion may be a suitable process for extending the fatigue life. The use of interference-fit bushes is not likely to be an effective method for extending the fatigue lives when large- size residual cracks are present. However, if such cracks can be machined out, the incorporation of large-size interference-fit bushes has the greater potential for providing not only significant extensions in life but also significantly longer lives than the original design detail.
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 01, 1983
- Accession Number
- ADA137771
Entities
People
- G. W. Revill
- J. Y. Mann
- W. F. Lupson