Non-destructive Maps of Stress Concentration Effects near Notches
Defence Research Establishment Atlantic Dartmouth, Nova Scotia Canada
Pagination or Media Count:
Recent advances in neutron detector technology and the ability of neutrons to penetrate through many millimetres of most engineering materials have made it feasible to investigate the effects of stress-concentration near notches. To demonstrate this capability, the development of the strainfield near a sharp notch in an HY -100 steel bar is scanned as a three-point bending load is increased to the point of metal-tearing. On unloading, residual stresses are scanned. As a second demonstration, the stress-concentration effects of a blunt notch in a tensile test specimen are presented. These measurements are performed at a temperature of 250 C, which is maintained by a heater that surrounds the specimen. In both examples, the gradients of the strain distribution are substantial, but neutron diffraction has a sufficient spatial resolution to characterize the effects of stress concentration quantitatively.