【作者】 潘翔；

【导师】 陈铭年；

【作者基本信息】 福建农林大学 ， 机械设计及理论， 2009， 硕士

【摘要】 我国的大中型客车车身骨架绝大多数是由型钢焊接而成的。受载后,高应力出现在型钢杆件的接头处。在接头处加焊角板是提高骨架强度和刚度以及提高轻量化水平的重要措施。然而,目前客车生产企业在生产实际中,对所添加角板的位置和参数仅凭经验,带有盲目性。因此,探讨接头角板对客车车身基本结构静态和动态性能的影响,寻找其影响规律,对指导客车车身设计是很有意义的。本文采用有限元分析法,使用ANSYS软件逐步探讨接头角板及其位置对客车车身基本结构静动态承载性能的影响。这些基本结构包括空间三杆结构,平面框架结构和箱型框架结构。此外,还研究了角板对客车基本结构轻量化的影响。通过有限元计算分析和归纳,得出以下结论:1)在接头处添加角板可以显著提高接头不规则的空间三杆结构的承载能力。对于主杆与两支杆接头无法平齐的情况,采取封闭主杆端面开口和添加角板的方法能够非常显著地提高该形式空间三杆结构的刚度和强度,应力减小系数达到80%以上。2)在接头处添加角板有效提高平面框架结构和箱型框架结构的承载性能,平面框架应力减小系数达到30%以上,箱型框架应力减小系数达到70%以上。3)采用分块Lanczos法分析客车车身基本结构的固有频率是可行的。ANSYS计算结果与解析法分析结果相比:截面相同的杆件,误差随着杆件长度的增加而减小;长度相同的杆件,误差随着杆件截面的增大而增大;截面、长度相同的杆件,单元划分精度对误差的影响小于1%4)在接头处添加角板,客车基本结构各阶振型特征不产生改变,但对固有频率产生影响。相对于其他振型特征,角板对框架结构各阶垂直弯曲固有频率的影响较大,但不超过5.5%。5)对客车车身基本结构加角板并减小杆件壁厚的轻量化改进方案是合理可行的,在本文所计算的例子中,减重效果达到7.5%以上。6)对空间三杆结构静态性能进行了电测试验,有限元计算结果与试验结果吻合良好,验证了所建有限元模型的合理性,也证明了有限元计算的可靠性。本文研究结果对客车车身结构的优化设计具有一定的参考和借鉴价值。对农业机械结构及其它工程结构设计等也有普遍的参考意义。更多还原

【Abstract】 The large-bus manufactured by our factory what’s body frame is mostly welded by section steel.The high stress will appears on the joints of section steel when it is loaded.Adding bracket on joints is the import measure to improve the load-carrying capacity and lightening of bus body frame.Actually,in the factory adding bracket joint all by experience,the method is cecity.Therefore, discuss the influence of adding bracket joint and its place on on static and dynamic performance of bus basic structure, in order to seek its law. So it can offer theoretical basis for bus body design.This thesis analyses the influence of adding bracket joint and its place on on static and dynamic performance of bus basic structure step by step through ANSYS software based on the finite element analysis.These structure include space bar stucture,frame stucture and box- stucture. From the calculation and experimental analysis, the following results can be summed up:1) Adding bracket joints can apparently raise the rigidity of space bar stucture with irregular joints.Obturateing the end hatch of main-bar and adding bracket joints of space bar stucture and can apparently raise the rigidity for it.The maximum equivalent stress drops by more than 80%.2) Adding bracket joints can apparently raise the rigidity of frame stucture, the maximum equivalent stress drops by more than 30% for the frame-stucture.the maximum equivalent stress drops by more than 70% for the box-stucture.3)It is feasible to analysis the natural frequency of bus basic stucture by Lanczos method. contrast the result of ANSYS software and analytical method,the following results can be summed up:for the bar with same size section,the error decrease with the length of bar increase.For the bar with same length,the error increase with the section of bar increase. For the bar with same length and section,the influence of the precision of element meshing is less than 1%.4) Adding bracket joints on bus basic structure,the vibration-type of bus basic structure is not change,but it make effect for the natural frequency of bus basic structure. Relative to other vibration-type, adding bracket joints make more effect on bend of frame stucture,less then 5%.5) It is feasible to lightning the body stuctrue by adding bracket joints and reduces the thickness of bar,the weight reduces more then 7.5%.6) Makes a electric measurement experiment for the static performance of space bar stucture, the calculation results accords with the experimental data well. It proves the rationality of models and the Reliability of FEM calculating.The research findings can offer the reference for optimization design of bus body.It also can be widely referred in agricultural mechanical structure and other engineering structural design etc.更多还原