液压挖掘机工作装置的疲劳寿命研究
发布时间：2019-05-24 15:20
【摘要】：液压挖掘机是广泛应用于工程建设、道路施工、农田水利建设的土方作业工程机械,其整机由上部回转平台、下部行走机构以及工作装置三大模块构成。工作装置是实现其功能的主要模块,由三组液压缸的伸缩运动控制。因液压挖掘机作业环境恶劣,作业对象复杂,工作装置作为直接进行挖掘作业的部分,其结构受力情况复杂多变,能否在服役年限内保证结构的疲劳强度是评价液压挖掘机性能的重要指标。工作装置在设计时一般采用校核挖掘机处于危险姿态、使用最大挖掘力挖掘时结构静强度指标的方法,然而工程机械的结构失效很大一部分是由于疲劳破坏,针对这一问题,论文以小型液压挖掘机为研究对象,结合计算机仿真与动态应力实验,计算了工作装置疲劳危险点的疲劳寿命。使用ADAMS建立液压挖掘机工作装置的刚体模型,分析了它的运动学特性并绘制挖掘轨迹包络图,得出挖掘机的各项性能参数。利用ADAMS和Ansys建立工作装置的刚柔耦合分析模型,模拟典型挖掘循环,获得了动臂和斗杆的动态应力—时间历程,为动态应力实验提供了参考。结合刚柔耦合仿真,对挖掘机样机的工作装置疲劳危险点进行了动态应力测试实验,实验数据经滤波、计算处理后获得了各点的动态应力—时间历程,在nCode DesignLife疲劳分析软件中使用雨流计数法进行了载荷统计,得到用于疲劳寿命估算的疲劳载荷谱。运用古德曼方法修正各级载荷平均应力的影响,用线性疲劳累积损伤理论的Miner法则对各点的疲劳寿命进行计算,得出了危险点的疲劳寿命。课题研究为液压挖掘机工作装置的动态应力仿真以及结构疲劳寿命计算提供了方法指导,同时此研究思路和实施方法也可应用于其它承受随机载荷的机械结构的疲劳强度研究。本课题得到建设机械国家重点实验室开放基金支持。
[Abstract]:Hydraulic excavator is a kind of earthwork construction machinery widely used in engineering construction, road construction and farmland water conservancy construction. its whole machine is composed of three modules: upper rotating platform, lower walking mechanism and working device. The working device is the main module to realize its function, which is controlled by the telescopic motion of three groups of hydraulic cylinders. Because the working environment of hydraulic excavator is bad and the working object is complex, the working device, as the part of direct excavating operation, has complex and changeable structural force. Whether the fatigue strength of the structure can be guaranteed during the service life is an important index to evaluate the performance of hydraulic excavator. In the design of the working device, the method of checking the excavator's dangerous attitude and using the maximum excavating force to excavate the static strength index of the structure is generally adopted. However, a large part of the structural failure of the construction machinery is due to fatigue failure. Taking the small hydraulic excavator as the research object, combined with computer simulation and dynamic stress experiment, the fatigue life of the fatigue dangerous point of the working device is calculated in this paper. The rigid body model of the working device of hydraulic excavator is established by using ADAMS, its kinematic characteristics are analyzed and the envelope diagram of mining trajectory is drawn, and the performance parameters of excavator are obtained. The rigid-flexible coupling analysis model of the working device is established by using ADAMS and Ansys to simulate the typical mining cycle, and the dynamic stress-time history of the moving arm and bucket rod is obtained, which provides a reference for the dynamic stress experiment. Combined with rigid-flexible coupling simulation, the dynamic stress test experiment is carried out on the fatigue dangerous point of the working device of the excavator prototype. The experimental data are filtered and the dynamic stress-time history of each point is obtained after calculation and processing. The load statistics are carried out by using rain flow counting method in nCode DesignLife fatigue analysis software, and the fatigue load spectrum for fatigue life estimation is obtained. Goodman method is used to correct the influence of load average stress at all levels, and the Miner rule of linear fatigue cumulative damage theory is used to calculate the fatigue life of each point, and the fatigue life of dangerous point is obtained. The research provides a method guide for the dynamic stress simulation and structural fatigue life calculation of the working device of hydraulic excavator. At the same time, this research idea and implementation method can also be applied to the fatigue strength of other mechanical structures subjected to random loads. This topic is supported by the Open Fund of the State key Laboratory of Construction Machinery.
【学位授予单位】：山东大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU621
本文编号：2484973
[Abstract]:Hydraulic excavator is a kind of earthwork construction machinery widely used in engineering construction, road construction and farmland water conservancy construction. its whole machine is composed of three modules: upper rotating platform, lower walking mechanism and working device. The working device is the main module to realize its function, which is controlled by the telescopic motion of three groups of hydraulic cylinders. Because the working environment of hydraulic excavator is bad and the working object is complex, the working device, as the part of direct excavating operation, has complex and changeable structural force. Whether the fatigue strength of the structure can be guaranteed during the service life is an important index to evaluate the performance of hydraulic excavator. In the design of the working device, the method of checking the excavator's dangerous attitude and using the maximum excavating force to excavate the static strength index of the structure is generally adopted. However, a large part of the structural failure of the construction machinery is due to fatigue failure. Taking the small hydraulic excavator as the research object, combined with computer simulation and dynamic stress experiment, the fatigue life of the fatigue dangerous point of the working device is calculated in this paper. The rigid body model of the working device of hydraulic excavator is established by using ADAMS, its kinematic characteristics are analyzed and the envelope diagram of mining trajectory is drawn, and the performance parameters of excavator are obtained. The rigid-flexible coupling analysis model of the working device is established by using ADAMS and Ansys to simulate the typical mining cycle, and the dynamic stress-time history of the moving arm and bucket rod is obtained, which provides a reference for the dynamic stress experiment. Combined with rigid-flexible coupling simulation, the dynamic stress test experiment is carried out on the fatigue dangerous point of the working device of the excavator prototype. The experimental data are filtered and the dynamic stress-time history of each point is obtained after calculation and processing. The load statistics are carried out by using rain flow counting method in nCode DesignLife fatigue analysis software, and the fatigue load spectrum for fatigue life estimation is obtained. Goodman method is used to correct the influence of load average stress at all levels, and the Miner rule of linear fatigue cumulative damage theory is used to calculate the fatigue life of each point, and the fatigue life of dangerous point is obtained. The research provides a method guide for the dynamic stress simulation and structural fatigue life calculation of the working device of hydraulic excavator. At the same time, this research idea and implementation method can also be applied to the fatigue strength of other mechanical structures subjected to random loads. This topic is supported by the Open Fund of the State key Laboratory of Construction Machinery.
【学位授予单位】：山东大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU621
【引证文献】
相关硕士学位论文 前4条
1 柳明珠;液压挖掘机斗杆结构的疲劳寿命研究[D];大连理工大学;2018年
2 董可心;斗轮堆取料机臂架疲劳寿命的仿真分析研究[D];吉林大学;2017年
3 李维多;WK-75型机械式挖掘机动臂的疲劳裂纹扩展寿命预测与分析[D];太原理工大学;2016年
4 李志勇;挖掘机工作装置力学分析系统开发与斗杆载荷谱编制[D];长安大学;2016年
，本文编号：2484973
本文链接：https://www.wllwen.com/jingjilunwen/jianzhujingjilunwen/2484973.html
