Abstract
Three-dimensional computation was carried out on the dynamic response of metal plate embedded at the different inclined cracks under parallel impact load. To describe the elastic-plastic material, an increase type of constitutive relationship was adopted and governing equation in Lagrangian form was solved by finite element method(FEM). Referring to LS-DYNA commercial code, six types of failure criteria based on stress and strain respectively indicate the fatigued elements which represent the cracks. During the loading, stress waves are generated which propagate inwards the plate and lead to the stress concentration around the crack tips. Meanwhile, new cracks are formed evolving from the crack tips. In contrast to the loading, the vertical cracks propagate perpendicularly and the parallel ones propagate horizontally. But these new cracks are independent of the inclination of the embedded cracks. The stress time history at each point in the plate is approximately related to the distance to the tips and either independent of the crack inclination. Moreover, the distances to the tips and plate frontier, and loading walls mainly affect the local strain time history. This means that the local strain is determined by the time integration of the plate loading. If the load amplitude is below a threshold value, the cracks do not prolong further. Otherwise, it takes a long time to release the strain energy concentrated around the tips, which postpones the appearance of the parallel cracks.
Abstract
Three-dimensional computation was carried out on the dynamic response of metal plate embedded at the different inclined cracks under parallel impact load. To describe the elastic-plastic material, an increase type of constitutive relationship was adopted and governing equation in Lagrangian form was solved by finite element method(FEM). Referring to LS-DYNA commercial code, six types of failure criteria based on stress and strain respectively indicate the fatigued elements which represent the cracks. During the loading, stress waves are generated which propagate inwards the plate and lead to the stress concentration around the crack tips. Meanwhile, new cracks are formed evolving from the crack tips. In contrast to the loading, the vertical cracks propagate perpendicularly and the parallel ones propagate horizontally. But these new cracks are independent of the inclination of the embedded cracks. The stress time history at each point in the plate is approximately related to the distance to the tips and either independent of the crack inclination. Moreover, the distances to the tips and plate frontier, and loading walls mainly affect the local strain time history. This means that the local strain is determined by the time integration of the plate loading. If the load amplitude is below a threshold value, the cracks do not prolong further. Otherwise, it takes a long time to release the strain energy concentrated around the tips, which postpones the appearance of the parallel cracks.
Open Access
JUSTC
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