【作者】 白瑞；

【导师】 程珩；

【作者基本信息】 太原理工大学 ， 机械电子工程， 2011， 硕士

【摘要】 液压挖掘机是工程机械领域中一种典型的土石方施工机械,在工业与民用建筑、道路建设、农田水利、油田矿由、市政工程、机场港口等部门的土石方施工中起到十分重要的作用。挖掘机在挖掘过程中负载变化剧烈,而其工作装置作为挖掘机完成各项动作的直接实施者,承受着各种各样恶劣工况下载荷的作用,因此挖掘机工作装置的强度、可靠性和耐久性直接关系到挖掘机的工作性能和工作效率,对工作装置的强度及可靠性研究也具有非常重要的意义。本文以某6吨小型挖掘机工作装置为研究对象,利用有限元软件Ansys对挖掘机工作装置进行了整体有限元分析。分析过程中,为使得分析结果更接近实际,将各铰接点处理为接触对,并对液压缸中的液压油进行了实体建模,将油液的相关参数赋予该实体,来模拟固液耦合对其性能的影响。同时利用应变测试系统测得工作装置各个测点的载荷-时间历程,经过分析处理,估算出各个测点的疲劳寿命。具体研究过程如下：(1)通过分析挖掘对象的特点和挖掘机挖掘时的切削动作,以及考虑实际工作条件下各种限制因素的制约,对挖掘机的挖掘阻力和整机理论挖掘力进行了系统分析,确定了挖掘机工作装置的6种典型工况,作为力学分析的主要姿态,并计算出了各种工况下的理论挖掘力。(2)对挖掘机工作装置进行整体有限元分析和模态分析,确定出工作装置在相应工况下的应力集中和刚度薄弱部位,为工作装置的维修和改进提供参考依据。(3)利用动态应变测试系统实测出挖掘机工作装置危险点的载荷历程,然后对载荷历程进行滤波、雨流计数统计后得到载荷历程中的各级循环应力,结合线性累积损伤理论和工作装置的S-N曲线,推导出各个危险点的疲劳寿命。更多还原

【Abstract】 Hydraulic excavator is a typical construction engineering machinery, which is widely used in industrial production, civil construction, road construction, water conservancy, oil mining, public works, airport and port construction, and other departments of the earth. The load changed violently in the mining process, and excavator working device, which is the direct implementation to complete working, bears the harsh load in the bad conditions, so excavator working device’s strength, reliability and durability is directly related to the excavator performance and efficiency. Therefore, the study of excavator working device’s intensity and reliability has a very essential significance.In this paper, a mini hydraulic excavator’s working device is researched, which is analyzed using finite element software Ansys, based on the overall finite element analysis method. In order to make the analysis more realistic, the hinge point is treated as contact, and the hydraulic oil in the hydraulic cylinder build as solid model. The relevant parameters will be given to the oil entity, in order to simulate the influence of the solid-liquid coupling to its performance. At the same time, the load time history of each test point is measured using strain test system, and the fatigue life of each point is estimated after analyzing the test result. A specific course of the study is as follows:(1) The excavator’s digging resistance and theory excavating force are analyzed systematic through analyzing the characteristics of digging objects and excavator’s digging action and considering the various constraints factors under actual operating conditions. The six typical conditions are determined as a major attitude of mechanical analysis, and the theoretical digging forces are calculated under various conditions.(2) In order to make the analysis more realistic, the hinge point is treated as contact, and the hydraulic oil in the hydraulic cylinder build as solid model. The relevant parameters will be given to the oil entity, in order to simulate the influence of the solid-liquid coupling to its performance. Through the overall finite element analysis and modal analysis of the excavator’s working devices, the weak parts of the stress concentration and stiffness are determined in the corresponding condition, which provide reference for the maintenance and improvement of the working device.(3) By using the strain measurement system, the load histories of the weak parts are measured in the paper. The load histories are analyzed with rain-flow counting method, and the structural S-N curve is corrected based on the fatigue test data of the material. The fatigue life of every test point is estimated by using the nominal stress method, which achieves the goal of fatigue life prediction of the working mechanism. This method can also give reference for the similar mechanism.更多还原