Abstract:
The process of occurrence of an internal crack of a mixed type (I and II fracture modes) in the wall of a pipe made of an ideal elastoplastic material under the action of combined tensile (compression) and bending loads has been studied. The process of destruction of such materials is described using a modified Leonov–Panasyuk–Dugdale model, which uses an additional parameter – the diameter of the plastic zone (prefracture zone width). The case of complex loading is considered, when the crack trajectory is necessarily curved, therefore the angle of the trajectory break is determined using a force integral criterion based on the asymptotics of the stress field in the vicinity of the crack tip. To obtain critical fracture parameters, a two-parameter (dual) strength criterion is proposed in the case of a complex stress state. An analysis of the parameters included in the resulting analytical model was carried out. The dimensionless geometric parameters of the structure are found numerically using the finite element method. Diagrams of quasi-brittle fracture have been constructed.
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