【作者】 徐建全；

【导师】 陈铭年；

【作者基本信息】 福建农林大学 ， 农业机械化工程， 2004， 硕士

【摘要】 本文论述了客车车身结构杆连接改进的重要性，综述了国内外研究汽车车身结构接头的进展。本文选择由闭口薄壁矩形钢管焊成的二杆结构，探讨L型接头加角板及其参数对客车车身基本结构刚度和强度的影响，以寻找其中的规律，从而为客车车身结构接头设计提供理论依据。 本文采用有限元法和ANSYS结构分析软件进行计算，并进行了实验验证。从计算和实验分析可归纳出下列结果： (1)加角板可显著提高客车车身基本结构的刚度。角板越大，位移减小系数也越大。位移减小系数几乎与所加的角板边长呈线性关系。在弯曲工况下，当角板边长≥38mm，位移减小系数都在10％以上。 (2)加角板可大幅度地降低客车车身基本结构接头处的最大米塞斯应力。角板越大，最大米塞斯应力下降得越多。角板边长≥38mm，最大米塞斯应力下降了25％以上。对于由两根等截面的方管或矩形管焊接而成的基本结构，在弯曲工况下，当角板边长与基本结构的厚度之比约为1.2时，应力下降趋于平缓。加角板后，最大米塞斯应力出现的位置有的发生了转移，有的没有发生转移。 (3)角板厚度对接头处的最大米塞斯应力影响较小。建议对于L型接头，若两根杆件壁厚一样，取角板厚度与杆件的壁厚一样。若两根杆件壁厚不一样，取角板厚度与两根杆件中壁厚较薄的一样。 (4)L型接头加直角边长不等的三角板后，基本结构产生的最大米塞斯应力，总体来说，介于加边长等于短边的等直角边三角板与边长等于长边的等直角边三角板之间。 (5)不加封闭板的圆弧角板，应力减小系数比同直角边长的三角板来得小。圆弧角板的圆弧半径越大，应力减小系数越大。 (6)加了带封闭板的圆弧角板后，应力减小系数比没加封闭板时来得大。但它与同直角边长的三角板比，并没有明显的规律。带封闭板的圆弧角板的圆弧半径越大，应力减小系数也越大。 本项研究成果对农业机械结构和其它工程结构设计等也有普遍的参考意义。更多还原

【Abstract】 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.更多还原