Effect Of Bracket Joints On Bearing Capacity Of Bus Basic Structure

The importance of joint improvement of bus structure has been discussed in this paper. And the domestic and international progress of studying the joints of automobile structure has been summarized. This paper selects two members which are welded by close thin wall rectangle steel tubes, discusses the influence of L-joint of adding bracket joint and its parameter on the rigidity and strength of bus basic structure, in order to seek its law. So it can offer theoretical basis for bus joint design.In this paper, it is calculated with finite element method and structural analysissoftware--ANSYS, and which is verified by the tests. From the calculation andexperimental analysis, the following results can be summed up:(1) Adding bracket joints can apparently raise the rigidity of bus basic structure. The bigger is bracket joint, the greater is the displacement relief coefficient. The relation between displacement relief coefficient and the side length of bracket joints that are added is nearly linear. Under bending loads, when bracket joint side length 38 mm; the displacement relief coefficient drops by more than 10%.(2) Adding bracket joints can greatly reduce the maximum equivalent stress of joints for bus basic structure. The bigger bracket joint is, the more maximum equivalent stress drops. Bracket joint side length 38 mm, the maximum equivalent stress drops by more than 25%. For the basic structure that is welded by two rectangle steel tubes or two square steel tubes, under bending loads, when the thickness of basic structure is divided by bracket joint side length, which is approximately 1.2, the stress decrease tends to be smooth. After adding bracket joints, transfer occurs to some of the locations of the maximum equivalent stress.(3) The thickness of bracket joint has less influence over the maximum equivalent stress of joints. For L-joint, we suggest that if two members have the same thickness, we take the same thickness of bracket joints as the members. If the thickness of twomembers is different, we take the thickness of bracket joints as the thinner member.(4) In general, L-joint of adding triangle bracket joints of different side lengths, the maximum equivalent stress of basic structure is situated between the triangle bracket joint that is equal to short side and the triangle bracket joint that is equal to long side.(5) As to the arc bracket joint which carries no adding close board, stress relief coefficient is less than the same right-angled triangle bracket joint. The bigger is the radius of arc bracket joints, the greater is the stress relief coefficient.(6) As to the arc bracket joint which carries adding close board, stress relief coefficient is bigger than arc bracket joint which carries no adding close board. But it is compared to the same right-angled bracket joint, which has no obvious law. The bigger is the radius of arc bracket joints which have adding close board, the greater is its stress relief coefficient.The research findings can be widely referred in agricultural mechanical structure and other engineering structural design etc.