Research On The Strengthand Fatigue Life Of The V-notched Structures

Based on the combination of Williams series expansions and the boundaryintegral equations, the non-singular stress terms in the full stress field at theV-notch tip are calculated. The effect of non-singular stress terms on the brittlefracture behavior of V-notched structures is assessed. Results show that thenon-singular stress terms have a significant role on the prediction of criticalloading of V-notched structuresespecially when mode-II loading is dominate.Then, the boundary element method is used to investigate the crackpropagation from the notch tip under fatigue loading. A comparison of the fatiguelife between the crack from the notch tip and a purely lateral crack is done by acrack propagation law until these two cracks have the same stress intensity factors.The singular stress gradient associated to a V-notch has a great role on the fatiguelife of V-notched structures. The growth rate of the crack initiated from the notchdepends on the singular stress state at the V-notch tip. The effect of the notchopening angle, the notch depth and the initial crack length on the crack extensionand propagation is analyzed.The tensile experiments on the PMMA V-notched plates are executed. Thecritical loadings achieved by the experiments and predicted by the present methodare compared. The results show that the present method is effective.Finally, the FEM software is applied to analyze the stresses of the joint plateunder different conditions during the construction process. The results are shownthat the maximum stress usually occurred at the notch tip. The existence of theV-notch has a great role on the engineering structures.