Abstract
The fracture mechanical behaviour of thin-walled structures with cracks is highly significant for structural strength design, safety and reliability analysis, and defect evaluation. In this study, the effects of various factors on the fracture parameters, crack initiation angles and plastic zones of thin-walled cylindrical shells with cracks are investigated. First, based on the J-integral and displacement extrapolation methods, the stress intensity factors of thin-walled cylindrical shells with circumferential cracks and compound cracks are studied using linear elastic fracture mechanics, respectively. Second, based on the theory of maximum circumferential tensile stress of compound cracks, the number of singular elements at a crack tip is varied to determine the node of the element corresponding to the maximum circumferential tensile stress, and the initiation angle for a compound crack is predicted. Third, based on the J-integral theory, the size of the plastic zone and J-integral of a thin-walled cylindrical shell with a circumferential crack are analysed, using elastic-plastic fracture mechanics. The results show that the stress in front of a crack tip does not increase after reaching the yield strength and enters the stage of plastic development, and the predicted initiation angle of an oblique crack mainly depends on its original inclination angle. The conclusions have theoretical and engineering significance for the selection of the fracture criteria and determination of the failure modes of thin-walled structures with cracks.
Highlights
Designed thin shells can withstand considerable loads, making them superior to thin plates
By applying the theory of maximum circumferential tensile stress of compound cracks, the node of the element corresponding to the maximum circumferential tensile stress is and plastic zones are investigated
For the cylindrical shell with a transverse crack subjected to a uniform tensile load in reference [29], the stress intensity factor (SIF) of the tensile mode is as follows
Summary
Designed thin shells can withstand considerable loads, making them superior to thin plates. Xie and Wang [4] proposed a simple method to determine the SIFs based on a new concept of crack surface widening energy release rate. Zhou and Huang [18] developed a method to determine the elastic deflection of the eccentric thin-walled columns containing some model-I cracks. The fracture parameters, plastic zones and crack initiation angles of thin-walled cylindrical shells with cracks are investigated using the finite element method. The finite element models of thin-walled cylindrical shells with circumferential cracks and compound cracks are established, respectively, and different loads such as axial tension, eccentric compression and the combination of tension and bending moment are applied. For the constitutive relationship of linear elastic materials, the SIFs of thin-walled cylindrical shells with circumferential cracks and compound cracks are calculated, based on the J-integral and the displacement extrapolation methods, respectively. By applying the theory of maximum circumferential tensile stress of compound cracks, the node of the element corresponding to the maximum circumferential tensile stress is and plastic zones are investigated
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