Papers by Keyword: Damage Mechanic

Abstract: Applied damage mechanics and coupled finite element method, to study the fatigue crack initiation life problem. Application of coupling finite element method, the damage coupling effect can be modified through the global stiffness matrix to achieve. The step length of the damage evolution is divided by the damage variable of the critical element, and then the damage evolution is analysised. The corresponding stiffness matrix and loading matrix can be obtained continually under the condition of increasing the damage evolution step of the critical element,then the equivalent stress can be calculated. The corresponding fatigue crack initiation life can be calculated by using the damage evolution equation, the progress will not stop until the damage degree of the critical element reaches to one. The fatigue crack initiation life is obtained by adding the fatigue crack initiation lives with different damage variable.

Abstract: Using coupied variational principle, predicting fatigue crack initiation life of plane stress state plate-like component which leads to large range damage is analysed. The closed form solution about predicting fatigue crack initiation life of plane stress state plate-like component which leads to large range damage is derived. The method adopted in this paper is definite in mechanical concept，it can be widely used in analysis of predicting fatigue crack initiation life of various plate-like component which leads to large range damage. A new thinking and new method is provided for predicting crack initiation life of plate-like component.

Abstract: The interfacial fracture strength in polymer blends is investigated in this study. The constitutive relations of polymeric matrix and inclusions are both approximately described by linear viscoelastic models. It is assumed that the interfacial de-boding between inclusions and matrix is dominantly induced by the hydrostatic component of remote stress. Based on the assumption, the interfacial de-bonding of a viscoelastic inclusion embedded in an infinite polymeric matrix is analyzed. It is found that the size of inclusion will strongly affect the magnitude of critical stress, and the effect of Poisson’s ratio on the de-bonding is so small that can be ignored.

Abstract: The Continuum Damage Mechanics is a branch of applied mechanics that used to predict the initiation of cracks in metal forming process. In this article, damage definition and ductile damage model are explained, and also ductile damage model is applied to predict initiation of fracture in gas metal forming process with ABAQUS/EXPLICIT simulation. In this method instead of punch, the force is applied by air pressure. In this study, first the ductile damage criterion and its relations are taken into account and, subsequently, the process of gas-aid formation process is put into consideration and ductile damage model for prediction of rupture area is simulated using ABAQUS simulation software. Eventually, the process of formation via gas on the aluminum with total thickness of 0.24 [mm] was experimentally investigated and the results acquired from experiment were compared with relating simulations. The effect of various parameters such as radius of edge matrix, gas pressure and blank temperature has been evaluated. Simulation was compared with experimental results and good agreement was observed.