【作者】 程宏川；

【导师】 王欣；

【作者基本信息】 大连理工大学 ， 机械工程， 2012， 硕士

【摘要】 在众多工程机械产品中,挖掘机占有重要的一席之地,被广泛的应用于道路施工等领域。从功能角度来说挖掘机一般被划分成三部分,即工作装置、回转机构和行走装置。工作装置(斗杆、动臂和铲斗)直接完成挖掘等任务,各部件的运动分别通过各自的油缸驱动来实现,姿态多样而灵活。行走装置能够保证整机的稳定性。由于挖掘机具有功能多等特点,同时能够实现灵活多样的工作姿态,其作业的复杂性主要体现在：(1)复杂的作业对象,由于挖掘的物料多种多样,如不同密度、不同硬度的土质、岩石等,导致挖掘机的受力情况复杂多变,实际挖掘力更是难以确定。(2)工作姿态的多样性,挖掘机的工作姿态是由工作装置的相对位置确定的,挖掘机属于多自由度系统,因此挖掘机能够实现多种姿态。疲劳破坏是机械结构主要的失效方式。小吨位的挖掘机由于使用量大,工作频次高,引起破坏的现象多而严重。因此针对以上问题,主要做了以下工作：(1)现场应力测试试验。通过测试挖掘机各个结构典型位置的应力应变,了解整车结构的应力分布状态,确定关键点的应力水平与变化规律,评价结构强度。同时获取实测载荷谱,作为疲劳分析的基础。(2)有限元分析。通过分析挖掘机的危险工况,了解结构的应力水平及状态分布,从而从强度角度判断结构的应力情况,同时ANSYS分析的结果文件作为疲劳寿命分析的输入文件输入到疲劳寿命分析软件中。(3)在疲劳寿命分析专业软件MSC.Fatigue2005中,通过加载实测载荷谱以及材料的S-N曲线,对原有结构进行寿命分析,据此结果改进挖掘机原有结构,与此同时,分析在相同工况、相同载荷谱、相同S-N曲线情况下改进后挖掘机的寿命。(4)对比ANSYS静力学分析结果和寿命分析结果,得出新的设计方案,并进行可行性分析,对今后挖掘机结构设计及改进提供了参考。更多还原

【Abstract】 Excavator, as a kind of important engineer machinery, is widely used in road engineering and other fields. It has three parts:working device, rotary device and running gear. For the working device, being articulated by arm、boom and bucket, it can complete mining tasks directly. All various and flexible movements are achieved by the relevant hydraulic cylinders. The running gear is used to ensure the stability of the whole machine.The versatility function is the typical characterization of an excavator, the complex are reflected in the following aspects:(1) the complexity of working objects. Various mining materials, such as soil and rock in different densities, lead to complicated force and elusive actual digging force of an excavator.(2) the diversity of working positions. The working position of excavator is determined by the relative position of the inclusive working device; importantly, excavator operating belongs to a multiple-degree-of-freedom system.Fatigue failure is the principle failure of mechanical structure. On account of being used extensively and frequently, excavators with small tonnage tend to damaged easily and seriously. In order to solve the problems aforementioned, this paper investigated the following questions:(1) Stress test. By testing the strain of typical positions for the structures, the stress distribution of vehicle structure is achieved. Then the stress levels and changing regularities of critical points can be determined further. In this way structural strength is evaluated and the actual load spectrum being treated as the basis of the fatigue analysis is obtained finally.(2) Finite element analysis. The stress levels and distribution of the structures are labeled by analyzing dangerous working conditions of excavator. To determine the stress of the structures from the perspective of strength, files for fatigue life analysis with results from finite element analysis are input into MSC.Fatigue2005.(3) Life calculation for excavator structure by loading actual load spectrum and the S-N curve of materials is analyzed by MSC.Fatigue. Then the original structures will be improved according to analytical results. Meanwhile, the improvement scheme life will be analyzed again to ensure the same condition, same load spectrum and same S-N curve.(4) The novel design scheme can be drawn out by comparing the static analysis of ANSYS and the results of fatigue life. Through the available structure improvements, to pave a reliable way for further structure design of excavators.更多还原