British Crystallographic Association Industrial Group

IG Home Newsletters Group Meetings Administration Industrial Applications Hints & Tips Group Information Site Map

Industrial Group of the BCA

Industrial Applications of Crystallography

The Metals and Alloys Industry

Aircraft Manufacture

Residual Stress Measurement Around Cold-Expanded Holes in High Strength Al Alloys

Cold-expansion of fastener holes to enhance fatigue resistance of aircraft structural joints is now widespread
At present, it is difficult to predict fatigue resistance through modelling and testing is still extensively used
To help improve models for predicting crack growth, the induced residual stress field can be measured
X-ray diffraction is the ideal non-destructive method to achieve this

Example

Experimental set-up showing a Posit ion Sensitive Detector being used to reduce data collection time. A fine collimated beam is used to enable the residual stress field to be mapped around the cold-expanded hole

Photograph of equipment

Plot showing hoop stress after cold-expansion as a function of pre-crack length in Al 7050 alloy



RS2 (0.5mm)

RS3 (1mm)

RS4 (3mm)

Stress Plot

Last updated 26 August 2002