THE EFFECTS OF SIMULTANEOUS OVERLOAD AND SPOT HEATING ON CRACK-GROWTH RETARDATION IN FATIGUE

A new method for the retardation of fatigue crack growth, spot heating at the crack tip combined with an overload, is described in this paper. A theoretical analysis indicates that the plastic zone size and the crack tip residual compressive stress region are larger using this method than is the case for simple overload. It is therefore suggested that fatigue crack retardation will be greater for the new method than for a simple tensile overload. Experimental investigations with single-edge cracked steel specimens were carried out. For the conditions investigated, crack arrests were observed after the application of the method, and the retardation effect was, indeed, far greater than that obtained with simple overload alone.