液压挖掘机动臂疲劳试验载荷谱编制方法

Compilation of load spectrum during fatigue test for boom of hydraulic excavator

为了研究液压挖掘机动臂构件的疲劳性能,提出了一种能够最大程度代表实测载荷数据,并广泛应用于同一吨位下不同机型的液压挖掘机动臂疲劳试验载荷谱编制方法。采集了 4 种典型工况下的载荷信号,并对其进行预处理。建立液压挖掘机的计算坐标系统,求解动臂各铰接点处的载荷,并将其等效为一个垂向载荷后,作为载荷谱编制过程中的输入信号。采用雨流计数法对压缩编辑后的信号进行统计计数。运用力的修正公式将非对称循环载荷谱转化为对称循环载荷谱。利用威布尔分布拟合幅值的概率分布。采用一步合成法实现工况的合成与外推。得到各级幅值及频次,形成 8 级疲劳试验载荷谱。提出的载荷谱编制方法和结果可为液压挖掘机动臂的寿命预测提供参考。

In order to study the fatigue performance of the boom of the hydraulic excavator,a load spectrum compilation method which can represent the measured load data to the greatest extent and is widely used in compilation of load spectrum from fatigue test for the boom of various models of the hydraulic excavator with the same tonnage was proposed.The load data in four typical operation modes were collected and preprocessed.The calculation coordinate system of the hydraulic excavator was established to solve the load at each hinge point on the boom.Then,the load was equaled to a vertical load and taken as the input signal in the process of load spectrum compilation.After that,the rain flow counting method was applied to count the compressed signals,and the force correction formula was applied to transform the unsymmetrical cyclic load into the symmetrical cyclic load.Weibull distribution was applied to fit the probability distribution of amplitude,and one-step synthesis method was used to realize the synthesis and extrapolation of the operation mode.The amplitude and frequency of each level were obtained,and eight-level fatigue test load spectrum formed.The proposed load compilation method and results offered reference for the life prediction of the boom of the hydraulic excavator.