【作者】 何强；

【导师】 王炳乐；

【作者基本信息】 重庆大学 ， 机械电子工程， 2007， 硕士

【摘要】 液压机作为一种重要的锻压设备在机械制造行业中占有重要地位,液压缸是液压机中的关键部件之一,以液压缸的法兰表面作为支承面的液压缸是各种液压机中采用最多的结构形式。其缸底及法兰均承受弯矩,特别是法兰过渡区应力集中表现得相当明显。液压缸的失效形式多数是疲劳破坏,主要是法兰过渡区产生疲劳裂纹。当然,这与实际的制造、安装及使用不当有关,但从设计方面考虑,关键在于过渡形线的好坏。本文对液压缸的法兰过渡区的过渡形线进行形状优化。首先,通过对液压缸破坏原因的探讨,法兰过渡区过渡形线现状的分析,作者研究了法兰过渡区降低应力集中的方法。作者在此基础上提出了两种新颖的过渡形线:内斜直线与圆弧组合过渡形线和内凹双圆弧过渡形线;并对此两种新颖的过渡形线进行了介绍。其次,运用弹性力学理论、环壳联解法编写了计算法兰支承液压缸应力的人机交互程序,并对现在常用的圆弧过渡形线和外斜直线与圆弧组合的过渡形线进行了计算分析。对内斜直线与圆弧组合过渡形线和内凹双圆弧过渡形线,进行了几何尺寸的计算、设计和分析。通过运用弹性力学理论的环壳联解法对上述四种过渡形线进行了较全面的比较、分析,作者认为内斜直线与圆弧组合过渡形线和内凹双圆弧过渡形线优于单圆弧过渡形线和外斜直线与圆弧组合的过渡形线。第三,作者运用有限元分析软件ANSYS对采用四种过渡形线的液压缸进行仿真分析。在分析过程中使用了三维等参元Solid186对液压缸模型进行了计算,然后再采用轴对称单元Plane82对计算结果进行了验证。基于两种单元计算结果的一致,可以确认采用两种新过渡形线液压缸的Von Mises应力较小,应力集中区也相对减少,其应力分布状况明显优于现有的采用其他过渡形线的液压缸。第四,通过ANSYS软件的Design Opt模块以液压缸的总体积为目标函数,以四种过渡形线的几何控制参数为设计变量,以液压缸过渡区的最大Von Mises应力为状态变量分别进行了一系列的优化工作,得到了最优解。通过对过渡形线的优化结果进行分析,作者提出了各过渡形线主要参数的取值范围,以便于工程技术人员参考。经过对四种过渡形线最优解的比较、分析,结果再次表明内斜直线与圆弧组合过渡形线和内凹双圆弧过渡形线优于单圆弧过渡形线和外斜直线与圆弧组合过渡形线。最后,通过ANSYS软件的Fatigue模块进行了疲劳耐久分析,结果表明采用此两种新型过渡形线的液压缸的疲劳耐久性表现良好,适合实际的工程需要。更多还原

【Abstract】 Hydraulic machine as an important forging equipment in machinery manufacturing industry occupies an important position, Hydraulic cylinder is one of the key components. Hydraulic cylinder of the flange surface to the bearing is an ordinary structure used up to the hydraulic machine. Its bottom and flange are under moment, in particular the stress concentration in flange transition zone is shown to be obvious. The failure mode of hydraulic cylinder is fatigue damage, which is fatigue crack in flange transition zone. Of course, the manufacture, installation and use of misconduct are main cause, But as a designer, the quality of transition curve is a key.In this paper, transition-curve of flange transition zone in the hydraulic cylinder will be optimized. Firstly, through researching the causes of damage of hydraulic cylinder, analyzing the transition curve of flange transition zone, the author studied methods of reducing stress concentration in the flange transition zone. Based on above research, the new two transition curve that are the curve of the inner bias and arc and the curve of the double arc were introduced. Secondly, depending the elasticity theory and the method of ring and shell combination, calculation program of the stress of bearing flange cylinder has been designed. The curve of single arc and the curve of outer bias and arc had been analyzed. The curve of the inner bias and arc and the curve of the double arc had been designed in geometric analysis. Through the application of elasticity theory and the method of ring and shell combination, above four curve of transition zone had been compared and analyzed. The researching proved that the curve of the inner bias and arc and the curve of the double arc were better than the curve of single arc and the curve of outer bias and arc. Third, the authors used finite element analysis software ANSYS to simulate and analyze the t four hydraulic cylinder. In the process of being analyzed, three-dimensional isoparametric element Solid186 and axisymmetric elements Plane82 were used. Finite element analysis showed that Von Mises stress of two new curve transition hydraulic cylinder was smaller, Stress concentration is correspondingly decreased, and the stress distribution is superior to the other existing transition curve of hydraulic cylinder. Fourth, in the Design Opt module of ANSYS software, the total volume of hydraulic cylinder was objective function, geometric parameters of transition zone were design variables, the largest Von Mises stress of the hydraulic cylinder were state variables. the optimal solution were found by a series of optimization. Through the optimization analysis, the authors listed the the main parameters value of transition curve. After analysis and comparison to the optimal solution, the result once again shows that the curve of the inner bias and arc and the curve of the double arc were better than the curve of single arc and the curve of outer bias and arc. Finally, using the Fatigue module of ANSYS software, hydraulic cylinder was loaded fatigue and durability analysis. The results show that two new curves of the transition zone had a good performance in fatigue durability and was suitable for the actual works.更多还原