Research On Mechanical Properties And Design Method Of Aluminum Alloy Bolt-sphere Joints

Aluminum alloy material is an ideal building material because of its excellent corrosion resistance,high strength,low density and light weight.In addition,the aluminum alloy also has easy processing,resistance to cold,good magnetic resistance,high reflectivity of light and other unique properties.Coupled with the recent decline in the price of aluminum alloy raw materials,aluminum alloy will be applied to the building structures more and more common.Aluminum alloy grid structures in the long-span roof structure are widely used,especially coastal buildings and industrial buildings which include corrosive substances.These structures can be said to be one of the most common form of the aluminum alloy structure.The main joints used in the spatial grid structure of aluminum alloy include gusset joints(Temcor joints),bolt-sphere joints,cast aluminum joints,hub joints,and so on.While the current "space grid structure technical code" is mainly aimed at the preparation of steel structures.There are few systematic guidelines for the design and application of aluminum alloy space grid structures.In addition,due to the impact of welding in the hot affected zone,the ultimate strength,tensile strength and plastic properties of aluminum alloy have a great reduction.Therefore,mechanical connections are commonly used in the joints.Due to lack of experimental research of joint connections,it is necessary to carry out research and experiment on the mechanical properties and design methods of aluminum alloy bolt-sphere joints.In this paper,the tensile and bending experimental study on the aluminum alloy bolt-sphere joint,which is applied in the FAST project of the National Astronomy Observatory of China,is carried out.By changing the depth of the stainless steel bolts into the aluminum alloy bolts,the failure mode of the stainless steel bolts was explored,and the minimum screw depth and design method of the bolts for aluminum alloy bolts were proposed.By changing the thickness of the sealing plate and the diameter of the aluminum pipe,the different failure modes of the sealing plate were explored and the failure mechanism was analyzed.The corresponding design methods were put forward,and the tensile mechanics performance of the aluminum alloy bolt-sphere joint was summarized.In addition,the bending test of the aluminum bolt-sphere joints was carried out,and its bending moment-angle curve was drawn.The semi-rigid performance of the joint was explored.In addition,the finite element model of stainless steel bolts and seal plate connections was established by means of correct finite element method,and the ultimate tensile capacity of different tensile specimens was obtained.The effectiveness and feasibility of the finite element simulation are proved by comparing with the actual test results.