基于损伤力学的矿用定向钻机金属结构寿命评估

Evaluation of Metal Structure Life of Directional Drilling Rig Based on Damage Mechanics

针对ZYL-15000D型煤矿用履带式全液压定向钻机底座寿命评估,首先通过Q345B钢的脉动循环加载拉伸疲劳试验数据,拟合得到应力幅值和寿命的关系式,经由应力修正和安全系数的选取,转换得到对称循环下的应力幅值和寿命的关系式。结合基于损伤力学推导出的损伤退化模型,根据Q345B钢试验数据拟合确定损伤退化模型中的待定参数,将Q345B钢对称循环下应力幅值和寿命的关系式代入,得到Q345B钢的疲劳损伤退化模型。然后借助ABAQUS对钻机整机进行结构分析,得到钻机底座的危险点位置(即应力最大处),在该型号样机试验台上通过应变片测得钻机底座危险点处的应力—时间历程。最后采用雨流计数和应力修正,对测得的随机载荷谱进行处理得到雨流计数直方图(应力均值-幅值-循环次数),再转换为对称循环载荷的形式,代入确定的疲劳损伤退化模型中,评估钻机底座的疲劳寿命。

In view of the life evaluation of ZYL-15000D type coal mine crawler hydraulic directional drilling rig base.Firstly,the relationship between stress amplitude and life is obtained by fitting the tensile fatigue test data of Q345B steel under pulsating cyclic loading.Then,the relationship between stress amplitude and life under symmetric cyclic loading is transformed by the selection of stress correction and safety factor.Combined with the damage degradation model derived from damage mechanics,the undetermined parameters in the damage degradation model are determined by fitting the test data of Q345B steel,and the fatigue damage degradation model of Q345B steel is derived by using the relationship between stress amplitude and life of Q345B steel under symmetric cycle.Then,the ABAQUS is used to analyze the structure of the whole rig,and the position of the dangerous point of the rig base(i.e.the place where the stress is the greatest)is obtained.The stress-time history of the dangerous point of the rig base is measured by a strain gauge on the prototype test bench.Finally,rain flow counting and stress correction are used to process the measured random load spectrum to obtain rain flow counting histogram(stress mean-amplitude-cycle),and then converted into the form of symmetric cyclic load,which is substituted into the determined fatigue damage degradation model to evaluate the fatigue life of the rig base.