基于ANSYS的自动扶梯桁架结构优化设计

发布时间：2018-10-13 17:57

【摘要】：自动扶梯的桁架结构起到支撑扶梯构件自重和外加荷载的作用。为了扶梯运转的安全稳定,采用过大规格型钢生产自动扶梯的桁架结构,使桁架的强度和刚度裕量过大,会带来钢材的大量损耗。随着数目增多,自动扶梯桁架的材料消耗问题日益突出。本文使用ANSYS软件来分析自动扶梯桁架结构,开展桁架的优化设计,为桁架的绿色制造、节材设计奠定基础。首先,结合桁架结构特点,利用ANSYS构建扶梯桁架中间段结构的有限元模型,根据现有扶梯桁架的实际载荷和几何参数,对桁架的受力状态、强度、刚度进行了分析,分析结果表明,现有桁架结构设计裕量过大,尚有很大的节材空间。通过静力学分析,揭示了桁架应力应变之间的本构关系,为桁架结构部分节材设计提供理论依据。接着,在扶梯桁架结构设计中引入了预应力技术。对桁架的应力应变关系进行分析与综合。即:在规定的荷载下求解桁架挠度及应力,分析各组实验数据后得出最佳拉力值;通过改变桁架结构,增加腹杆长度使扶梯桁架在制造后就产生内部初始应力,在规定的荷载下分析扶梯桁架结构的挠度,并加以有效控制。最后,对单边扶梯桁架结构进行最优化分析,以单边扶梯桁架结构的钢材体积为目标函数,在桁架结构最大位移与最大应力范围内,求解出扶梯桁架结构各梁杆的截面参数的最优化值。使用与该值最大近似的标准型钢规格更新桁架模型,验证分析得桁架仍然具有足够的安全系数。主要研究结论如下:(1)原扶梯桁架采用的型钢规格过大。将原扶梯桁架结构杆件更换为规格较小的型钢后,其强度和刚度仍能满足规范要求;分析扶梯桁架结构上下弦杆内应力情况得:减小下弦杆型钢规格,可进一步减少钢材消耗。(2)在自动扶梯的桁架制造或安装过程中引入预应力技术,扶梯桁架结构挠度能有效控制,内部应力状态更为理想。施加预应力的扶梯桁架可减小梁杆截面参数,节约钢材。(3)运用ANSYS结构有限元高级分析方法对自动扶梯桁架结构进行最优化分析。参考最优化梁杆截面参数更新桁架模型,经验证优化后桁架强度刚度满足要求,而且大幅降低扶梯桁架的钢材使用量。
[Abstract]:The truss structure of the escalator plays the role of supporting the dead weight and the external load of the escalator member. In order to ensure the safety and stability of escalator operation, too large size steel is used to produce the truss structure of escalator, so that the strength and stiffness margin of the truss is too large, which will bring a large loss of steel. As the number of escalator trusses increases, the material consumption of escalator truss becomes more and more serious. In this paper, the ANSYS software is used to analyze the escalator truss structure and carry out the optimization design of the truss, which lays the foundation for the green manufacture and the material saving design of the truss. Firstly, according to the characteristics of truss structure, the finite element model of the middle segment of escalator truss is constructed by using ANSYS. According to the actual load and geometric parameters of the existing escalator truss, the stress state, strength and stiffness of the truss are analyzed. The results show that the design margin of the existing truss structures is too large, and there is still a lot of room for saving materials. The constitutive relationship between stress and strain of truss is revealed by statics analysis, which provides a theoretical basis for the design of some sections of truss structure. Then, the prestressed technology is introduced in the design of escalator truss structure. The stress-strain relationship of truss is analyzed and synthesized. That is to say, the deflection and stress of truss are solved under specified load, and the optimum tensile force is obtained after analyzing each group of experimental data. By changing the truss structure and increasing the length of web bar, the initial internal stress of the escalator truss is produced after manufacture. The deflection of the escalator truss structure is analyzed under the specified load and effectively controlled. Finally, the optimization analysis of the single side escalator truss structure is carried out. Taking the steel volume of the single side escalator truss structure as the objective function, the maximum displacement and stress range of the truss structure are obtained. The optimum values of the cross-section parameters of each beam and rod of the escalator truss structure are obtained. The truss model is updated with the standard steel specification which is similar to the maximum value, and it is verified that the truss still has enough safety factor. The main conclusions are as follows: (1) the size of section steel used in the original escalator truss is too large. The strength and stiffness of the members of the original escalator truss structure can still meet the requirements of the code after replacing the members of the original escalator truss structure with the section steel of smaller specification, the stress in the upper and lower chords of the escalator truss structure is analyzed, and the following conclusions are obtained: reducing the steel specification of the lower chord, The steel consumption can be further reduced. (2) the prestressed technology is introduced in the manufacture or installation of the escalator truss. The deflection of the escalator truss structure can be effectively controlled and the internal stress state is more ideal. The prestressed escalator truss can reduce the cross section parameters of the beam bar and save steel. (3) the optimization analysis of the escalator truss structure is carried out by using the advanced finite element analysis method of ANSYS structure. The truss model is updated with reference to the optimized beam and rod cross-section parameters. It is verified that the strength and stiffness of the optimized truss meet the requirements and the steel usage of the escalator truss is greatly reduced.
【学位授予单位】：江苏大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TH236

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