Study On The Stable Bearing Capacity Of Double L Aluminum Alloy Axial Compression Member

Aluminum alloy structure has been developed rapidly in recent years because of its nonmagnetic and good corrosion resistance.At present,due to the node problem of aluminum alloy lattice shell structure,the commonly used lattice shell structure is prone to overall instability under large span,so Tianjin university provides a truss type aluminum alloy double-layer space grid structure,whose members include H type and double L type aluminum alloy members.At present,the research on h-type aluminum alloy components is relatively mature.There is no detailed study on double-jointed bolted aluminum alloy members in China.It is necessary to study the stability of double-jointed L-shaped aluminum alloy members in order to popularize the truss double-layer spatial grid structure.The main research results of this paper are as follows:1.16 double-split-equilateral L-type aluminum alloy axial compression members and 16 double-split-equilateral L-type aluminum alloy axial compression members were designed,the stability bearing capacity was studied,and the influence of the section type,length-fineness ratio,height-width ratio and other parameters on the ultimate load and failure morphology was analyzed.The test results show that :(1)The members with obvious strong and weak axes in section all bend and buckle,and when the length and thickness are small,the overall instability is accompanied by local buckling.The failure mode of members with no obvious strong or weak axis is bending and torsional instability around the axis of symmetry.(2)The stability coefficient of all specimens decreases as the ratio of length to thickness increases;(3)The smaller the aspect ratio,the more prone to local buckling.2.Finite element analysis was carried out on 32 test members by software ABAQUS,and the accuracy and effectiveness of the model in predicting the stability of double-assembld L-type aluminum alloy members under axial compression were verified by comparing the finite element results with the ultimate load and failure mode of corresponding tests.On the basis of this,various factors influencing the stability bearing capacity of the members(including the ratio of width to thickness,initial bending,material characteristics,thickness of the filling plate,etc.)are analyzed by numerical simulation.The results show that :(1)The initial bending,width to thickness ratio and filling plate thickness have certain influence on the stability coefficient of double-split L-type aluminum alloy axial compression members,and the smaller the length to thickness ratio is,the more obvious the influence is.(2)The material hardening index has little influence on the stability coefficient of components.3.The finite element models of L-shaped aluminum alloy members and T-shaped aluminum alloy members were established,and the bearing capacity of double-shaped L-shaped aluminum alloy members was compared with the double bearing capacity of L-shaped aluminum members and T-shaped aluminum members,and the combination effect of double-shaped L-shaped aluminum alloy members was obtained through analysis.In the end,the design method of double spell L-shaped aluminum alloy members under axial compression is studied,and the calculation formula of stability coefficient is given.By comparing the proposed formula with the pillar curve of the European code and the Chinese code,the results show that the pillar curve of the proposed formula is close to the lower envelope and safe,which can be applied in practical engineering.