Synchrotron Strain Mapping of the Residual Strain Distribution around Foreign Object Damage in Laser Shock Peened Ti-6AL-4V Alloy
The current study investigates the effect of foreign object damage (FOD) on the pre-existing compressive residual stress field associated with laser shock peening (LSP) and its evolution upon combined LCF/HCF cycling. FOD was introduced onto an aerofoil-shaped specimen that had been previously LSP treated through ballistic impacts at angles of 0° and 45° to the leading edge. It is shown that the FOD notch created by 45° impact was asymmetric in shape and smaller in depth compared to that created at 0° impact. Significant through thickness compression was introduced parallel to the leading edge as a result of the LSP process. The residual strain distribution was mapped around the FOD notch by synchrotron X-ray radiation. The results show predominantly compressive stresses ahead of the notch, being greater for the 0 compared to 45 impact. No significant stress relaxation was observed after a combined (1000 HCF cycles superimposed on 1 LCF cycle) cycle.
Y. Akiniwa, K. Akita and H. Suzuki
S. Zabeen et al., "Synchrotron Strain Mapping of the Residual Strain Distribution around Foreign Object Damage in Laser Shock Peened Ti-6AL-4V Alloy", Materials Science Forum, Vol. 652, pp. 19-24, 2010