Effect Of Local Imperfection On Buckling Failure Of Thin-wall Structure

Thin-walled structures are very popular in the fields of aviation and aerospace,marine, automobile, chemical, construction and other engineering practice in whichbuckling failure of thin-walled structures under the surface pressure is the commonfailure mode, especially for structures containing defects. Take account of access forinspection, maintenance or simply weight loss, openings in such thin-walled structuremay be required. However, the presence of such openings in thin-walled structureselements leads to change in stress distribution within the member and variations inbuckling characteristics of the element. In the case that the thin-walled structures aresubjected to axial compression load, the stress and deformation around the openingincreases and the buckling bearing capacity decreases, which make them prone toinstability or buckling. The investigation of the buckling failure behavior ofthin-walled structures with opening under loads and the analysis of the effect of holesize, hole locations and other geometric parameters on buckling bearing capacity canprovide reference for openings design of engineering structures.Considering the working environment of thin-walled plate, it is often subject tothe effect of temperature changes. If the deformation is constrained, a compressivestress block will be presented. When the temperature rises to a certain value, thestructural buckling happens and resultantly rapid destruction is suddenly emergedwhich is named as thermal buckling. Generally, the structure will be influenced bymechanical loads simultaneously which will bring complexity of thermal bucklinganalysis. Thermal expansion and the material properties changes caused by localheating of thin-walled structures will affect the bearing capacity of thin-walledstructures and buckling failure mode. It has an important application value toinvestigate buckling failure mode of thin-walled structures on condition of localheating and analyze the effect of temperature on the bearing capacity of the structurefor the high temperature protection materials research and the protection structuredesign.Based on numerical simulation method, the main contents of the article include:(1) Linear and nonlinear buckling of thin-walled structures with opening underin-plane loading were investigated by subspace iteration method and riks method,which considered the effect of geometric parameters such as boundary conditions, hole shape, hole size and hole location on buckling bearing capacity. The change ruleof buckling bearing capacity with the changing of geometric parameters wassummarized. Based on the theory of elastic buckling, the empirical expressionsabout the relationship of critical buckling load and various geometrical defects such ashole shape, hole size and hole position were obtained through fitting calculation,providing reference for openings design of sheet structure.(2) Through thermal analysis of local heating thin-walled structures, temperaturedistribution and change rule of temperature variation of nodes to time of structureunder different time were obtained; Stress distribution of structure at differenttemperatures was obtained through extracting temperature distribution at differenttimes and conducting thermal stress analysis of thin-walled structures; Consideringthe material parameters change with temperature, take the thermal stressaforementioned as the initial stress, buckling analysis of thin-walled structures wasconducted, the critical buckling load of the structure was obtained and influence ruleof temperature on the buckling capacity was summarized.(3) Linear and nonlinear buckling of thin-walled cylindrical shell with openingunder axial compression were investigated by lanczos method and riks method.Fitting formulas of elastic buckling load of cylindrical shell structure with openingwas obtained and the effects of hole size and hole location on buckling bearingcapacity were analyzed. The results show that the buckling analysis considering thedouble nonlinearity of geometric and material, the critical buckling load of thincylindrical shell structure decreased rapidly as the hole size increased and therelationship between them is approximately exponential; critical buckling load of thincylindrical shell decreased linearly as the distance of the hole center along the fixedend of the cylindrical shell increased.