ANALYSIS AND TESTING OF SURFACE COLD-WORK PROCEDURES APPLIED TO NOTCHED, FLAT ELEMENTS

Several surface cold work procedures are developed to induce compressi ve residual stresses adjacent to a notch in a flat element. It would a ppear that they should all lead to fatigue life enhancement. For sharp notched specimens excellent fatigue life enhancement is observed. For moderately notched specimens only one of the procedures produces this enhancement. In order to shed light on the shortcomings of two of the procedures, the residual stress field is determined by means of finit e element analyses in two and three dimensions. It is observed that th e two-dimensional analyses predict a residual stress field which shoul d lead to fatigue life enhancement. It is the three-dimensional analys es which help to explain why two of the cold work procedures fail.