装载机动臂疲劳试验的模拟加载研究

发布时间：2018-03-10 06:02

本文选题：装载机动臂　切入点：载荷谱　出处：《集美大学》2014年硕士论文　论文类型：学位论文

【摘要】：随着装载机朝着大型化、重型化和高速化发展，，对装载机的安全性、可靠性等工作性能提出了更高的要求，装载机车架和执行结构的主要破坏形式是交变载荷作用下长期积累而导致的疲劳失效。本课题建立在与企业联合研究开发的装载机疲劳试验台架的基础上，通过装载机整车疲劳试验，研究装载机台架疲劳试验与实际工况下动臂疲劳失效的等效机理。通过等幅加载疲劳试验推断动臂在现实作业中的疲劳寿命及失效形式、失效位置，以便于进行产品的开发、质量控制等。并为其它型号装载机在该试验台架上的应用以及装载机的加速寿命试验仿真研究奠定基础。本论文主要研究内容包括：（1）装载机铲斗实际受力计算及实验室工况加载谱的编制。根据实验室加载情况对被试装载机铲斗受到的动载荷进行计算；采用库伦土压力理论分析计算装载机从铲斗插入料堆至卸载物料、铲斗降回原处整个过程铲斗受到的铲装阻力计算。根据实验室的加载情况满足正负峰对称分布以及无中间过渡峰的要求，以及理论计算加载得到的载荷循环较平滑、峰值变化频率较平缓的特点，分别采用全峰值计数法和振程计数法对所计算获得的样本进行计数并编制成载荷谱。（2）基于材料S-N曲线，对装载机动臂的S-N曲线进行修正，并进行装载机动臂疲劳寿命预测。本文运用建模软件PRO/E建立装载机的实体模型，并导入前处理软件Hypermesh中进行网格划分、添加实验室工况和理论计算下载荷和约束状态，导入Ansys中计算处理以获得装载机动臂在实验室工况和理论计算下应力分布情况。并计算获得动臂在特定载荷环境下的应力集中系数，基于材料的S-N曲线，结合对动臂S-N曲线影响因素进行分析计算修正得到相应动臂的S-N曲线。通过获得的动臂S-N曲线，并结合线性累积疲劳损伤理论对载荷循环进行统计，预测其疲劳寿命。（3）装载机动臂台架疲劳试验与理论计算疲劳失效的等效机理研究。运用灰色关联度理论对装载机动臂实验室工况与理论计算下疲劳预测曲线二者的相关性进行分析，得到两者关联度系数为0.9012的结果；通过加速因子对实验室工况与理论计算下的疲劳寿命预测折算分析两者关联度密切性；建立基于灰色关联度的等幅谱预测模型，分析实验室等幅谱预测模型与实际疲劳预测曲线的吻合度，并可以通过建立多个预测模型或者建立残差模型提高模型的预测精度。
[Abstract]:With the development of loaders towards large scale, heavy duty and high speed, higher requirements are put forward for the safety and reliability of loaders. The main failure form of loader frame and executive structure is fatigue failure caused by long-term accumulation under alternating load. In this paper, the equivalent mechanism of the fatigue failure of the loader bench fatigue test and the moving arm fatigue under the actual working condition is studied through the fatigue test of the loader, and the fatigue life, failure form and failure position of the arm are inferred through the fatigue test of equal amplitude loading. It is convenient for product development, quality control and so on. It also lays a foundation for the application of other types of loaders on the test stand and the simulation study on the accelerated life test of loaders. The main contents of this thesis are as follows:. 1) calculation of the actual force of the loader bucket and compilation of the loading spectrum of the laboratory conditions. The dynamic load of the hopper of the loader is calculated according to the loading condition in the laboratory; The Coulomb earth pressure theory is used to analyze and calculate the loading machine from the bucket insert material pile to the unloading material. According to the loading conditions of laboratory, the symmetrical distribution of positive and negative peaks and the requirement of no intermediate transition peak are satisfied, and the load cycle obtained by theoretical calculation is smoother. The peak frequency is relatively gentle. The full peak counting method and the vibration range counting method are used to count the calculated samples and the load spectrum is compiled. Based on the material S-N curve, the S-N curve of the loader arm is modified and the fatigue life of the loader arm is predicted. In this paper, the solid model of the loader is established by using the modeling software PRO/E, and the mesh is divided into the pre-processing software Hypermesh. Add laboratory conditions and theoretical calculations to download load and constraint states, In order to obtain the stress distribution of the loader arm under the laboratory condition and the theoretical calculation, the stress concentration factor of the arm under specific load environment is calculated, based on the S-N curve of the material. The S-N curve of the corresponding arm is obtained by the analysis and correction of the influence factors of S-N curve of the arm. The fatigue life of the arm is predicted by the S-N curve of the arm and the statistics of the load cycle combined with the linear cumulative fatigue damage theory. 3) the equivalent mechanism of fatigue test and theoretical calculation fatigue failure of loader arm is studied. The correlation between the fatigue prediction curve and the laboratory condition of loader arm is analyzed by using the grey correlation degree theory. The correlation coefficient is 0.9012; the fatigue life prediction under the laboratory condition and the theoretical calculation is converted by the acceleration factor; the correlation degree between the two is analyzed; and the equal amplitude spectrum prediction model based on the grey correlation degree is established. The prediction accuracy of the model can be improved by establishing multiple prediction models or residual models.
【学位授予单位】：集美大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U653.92

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