ON PLANE-STRESS PLANE-STRAIN INTERACTIONS IN FATIGUE-CRACK GROWTH

Fatigue crack growth studies have been carried out on steel and alumin um specimens of two thicknesses, 0.3 and 6.35 mm. For fatigue crack gr owth rates in the range 10(-5)-10(-4) mm/cycle, the process of fatigue crack growth in plane stress (as well as in the surface layer of a no minally plane strain specimen) was discontinuous in nature, whereas fa tigue crack growth in plane strain occurred on a cycle-by-cycle basis. A slower rate of fatigue crack growth was also observed in the thinne r specimens, a circumstance attributed to a higher level of crack clos ure. (C) 1998 Elsevier Science Ltd.