SHORT FATIGUE CRACK GROWTH UNDER MEAN STRESS, UNIAXIAL LOADING
单向加载,平均应力下的疲劳短裂纹生长

An investigation of the effects of mean and alternating stresses on short fatigue crack growth under uniaxial loading is reported. Tests under stresscontrolled conditions with different combinations of mean and alternating stresses were conducted at room temperature using a 1.99% NiCrMo steel. The fatigue process was divided into three phases: Plasticity Localization, Microstructural Short Crack (MSC) growth, and Physically Short Crack (PSC) growth. The effect of mean stress on the above three phases is studied and a set of equations is obtained which can predict the early stage and growth behaviour of short cracks under various mean and alternating stresses. Satisfactory predictions of fatigue endurance curves at different mean stresses have been achieved. This approach provides an alternative method, based on the physics of the fatigue process, for use by designers who currently rely on conventional Goodman-type diagrams.