A solution to the double crack's J-integral in the plain plate

Based on the relevant criteria and theory of fracture mechanics and the description and definition of corresponding fracture parameters, the J integral factor of double crack propagation in plain plate is analyzed. In order to obtain the J integral factor of double crack propagation, the method of defining seam is used to preset the path of crack's propagation. With the variation of load, the crack would be acquired a propagation forward to the presetting seam, furthermore, and simulated the singularity of crack tip, the stress field, displacement field and strain field at the crack tip are analyzed for the causes and regular changes. The model under the same load is also calculated using the model of the viscoelastic plate, and the corresponding regular changes and discussions are also given. The result is showed that the distribution of stress about crack tip is more larger than other district, concentration of stress is so obvious, the value of stress is more decreasingly less than other distribution; the strain of crack tip would acquire an increasing tendency to the direction of crack propagation, the displacement's magnitude also presents a significantly growth across the central point toward both sides, and the value of displacement is largest of the both sides of plate. Compared to the classical elastic plate, the J integral factor is smaller, and the strain energy according to the crack tip is less. (paper)