Elastic-plastic Fracture Mechanical Behavior Of Thin-walled Cylindrical Shells With Circumferential Cracks

The demand for steel thin-walled tubes in industrial and civil buildings and structures is increasing.This is because steel structures have many characteristics such as high strength,light weight,short construction period,and recyclable use.However,in the actual steel structure members,cracks always exist due to manufacturing process or other reasons.The actual strength of the material is much lower than the strength of its theoretical model.Therefore,there is a great hidden danger in the safety of the structure.The possible failure behaviors of cracked components include fracture failure and plastic limit failure.In this paper,the plastic zone,J-integral,and plastic limit load of the thin-walled cylindrical shell with circular cracks are studied under the ideal elastic-plastic material model.The size of the plastic zone on the crack front of a thin-walled cylindrical shell was studied.The influence of load size,crack length,yield strength and thickness of cylindrical shell on the results is analyzed when the cylindrical shell is subjected to axial tension.When the cylindrical shell is eccentrically compressed,the effects of load size,crack length and load eccentricity on the results are analyzed.In this paper,the shape of the plastic zone obtained by numerical simulation is consistent with the shape obtained by the analytical solution,and the change law of the plastic zone with increasing load is obtained.The whole process of crack initiation of cracked thin-walled thin-walled columns from small-range yield to large-range yield and eventually to full-scale yield was analyzed.The parameter J-integral describing the stress-strain field strength of elastic-plastic fracture was studied.The influence of load size and crack length of cylindrical shell on the results is analyzed when the cylindrical shell is subjected to axial tension.When the cylindrical shell is eccentrically compressed,the effects of load size,crack length and load eccentricity on the results are analyzed.The relationship between J-integral and stress intensity factor K under small-range yield conditions was verified.The plastic limit load of thin-walled cylindrical shells with circumferential cracks was studied.The influence of load form,crack length and thickness of cylindrical shell on the results is analyzed when the cylindrical shell is subjected to axial tension.When the cylindrical shell is eccentrically compressed,the effects of column length,crack length and load eccentricity on the results are analyzed.For different types of loads,the presence of cracks has different effects on the plastic ultimate load.The smaller the wall thickness of a thin-walled column is,the smaller the ultimate load it can bear.The larger the load eccentricity is,the smaller the ultimate load of thin-walled columns will be.