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FEM simulation of fatigue damage crack nucleation andgrowth in a pre-damaged materialIgor
Last modified: 2013-03-15
Abstract
A FEM-based procedure of fatigue crack growth simulation in the field ofprogressive damage is developed. A new finite element grid is suggested to considerfatigue damage accumulation and crack growth based on a unified point approach. Thegrid design suggested allows saving information on accumulated damage and“natural” tracing of growing crack, which is timely and laborious using the standardFEM-procedures. The basic principles of meshing are formulated and following theseprinciples a two-level finite element grid was designed. With application of the assumedgrid fatigue behavior under cyclic loading of a thin rectangular plate with initialrandomly distributed defects is analyzed. The plate is considered a composition of finiteelements representing material elements with randomly distributed fatigue resistanceparameters. Defects in material structure are modeled by elements with negligibly smallstiffness. The fatigue properties of the material elements are described by the Basquinequation. The trajectories of growing cracks and the damage accumulation in the plateare presented at different phases of fatigue life.The procedure developed is deemed an effective mechanism that allows both tomodel the crack formation from a defect and its further propagation in accordance withthe damage accumulation during all period of loading. It allows to reduce drasticallythe influence of the mesh geometry on the crack growth trajectory.
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