Stability Reserch Of Thin-wall Structure With Compound ?-? Cracks

With the advancement of science and technology and the diversification of human needs for various types of structures,thin-walled components are increasingly used in modern construction,bridges and other engineering projects.However,during the processing,transportation and use of materials,bubbles,initial bending and cracks are unavoidable.Since the wall thickness of the thin-walled member is small compared to the cross-sectional dimension,and the cross-sectional size is relatively small compared to the length of the rod of the structure,the stability problem of the thin-walled member is particularly prominent.However,for the stability analysis of thin-walled components,the influence of cracks on the critical load of thin-walled components is less considered.Therefore,this topic is of great significance.The stability of thin-walled shell structures with cracks is a new problem that the engineering community needs to pay close attention to.To establish a thin-walled cylindrical shell structure design method with oblique cracks,we must study for the buckling analysis of thin-walled cylindrical shell structures with I-II composite cracks under different stress conditions and different cracking conditions,and the influence of various factors on the buckling load.To find the universally applicable relationship between buckling loads and cracks in thin-walled structures.Based on this,the research content of this paper mainly includes:Analysis of structural stability of axially loaded thin-walled cylindrical shells with oblique cracks,using finite element buckling analysis theory,the stability of axially compressed thin-walled cylindrical shells with oblique cracks was studied.A preliminaryanalysis of the equilibrium path of the structure was conducted,and the influence of the crack length ? and the crack angle ? on the equilibrium path of the thin-walled cylindrical shell with cracks was analyzed.The buckling loads of thin-walled cylindrical shells with I-II complex cracks under axial pressure are calculated.The influences of crack length and crack angle on the buckling load of thin-walled cylindrical shell structures with different slenderness ratios and different ratios of diameter to thickness were analyzed.Stability analysis of thin-walled cylindrical shell with inclined crack under eccentric compression.Based on the finite element buckling analysis theory,the stability of the thin-walled cylindrical shell with oblique cracks under eccentric compression is studied.The influence of eccentricity on the equilibrium path of thin-walled cylindrical shells with oblique cracks was analyzed.The buckling loads of thin-walled cylindrical shells with I-II composite cracks with different eccentricities under eccentric pressure are studied.The effect of cracks on the buckling load is analyzed by changing the eccentricity of the structure.The effects of crack length and crack angle on the buckling load of eccentric thin-walled cylindrical shells were studied.From the above studies,we find that the crack length ?,the crack angle ?,and the structural eccentricity ? all affect the equilibrium path of the structure.When the crack length ?>0.35 and the structural eccentricity ?>3.5,the structure will be more susceptible to instability.But the change of the crack angle ? will have different effects on the equilibrium path of the structure.The increase of crack length ? and eccentricity ?will reduce the buckling load of the structure.When the crack angle ? is between 0° and 25°,the buckling load of the structure decreases rapidly.The buckling load of the thin-walled cylindrical shell members with slenderness ratio ?<120 and diameter-to-thickness ratio ?<20 is more sensitive to changes in crack length.