考虑杆件尺寸相关性的受电弓运动可靠性分析

Pantograph Kinematic Reliability Analysis Considering the Correlation of Rod Size

为分析杆件尺寸参数的关联特性对机构运动可靠性的影响规律,提出一种基于Cholesky法则的机构运动可靠性分析方法。首先,根据机构运动学原理构建机构运动学方程;其次,结合有效长度理论,建立考虑运动副间隙的杆件有效长度模型,在此基础上,引入Archard磨损模型量化运动周期对杆件有效长度的影响,通过蒙特卡罗法获取不同运动周期下的杆件尺寸样本数据并计算样本相关系数,进而利用Cholesky法则完成不同运动周期下的杆件样本数据重构,并结合可靠性理论对机构运动可靠性进行评估;最后,以受电弓机构为例,验证了所提方法的有效性。计算分析结果表明:杆件样本数据关联性由于运动副间隙的存在而增强,并随运动副间隙的增加愈加显著;与传统分析方法相比,基于Cholesky法则的机构运动可靠性指标存在一定程度降幅,能够为实际机构可靠性评估提供更为安全的参考价值。

In order to analyze the influence of the correlation characteristics of rod size parameters on the motion reliability of mechanism,a mechanism motion reliability analysis method based on Cholesky rule is proposed.Firstly,the kinematic equation of the mechanism is constructed according to the principle of mechanism kinematics.Secondly,combined with the effective length theory,the effective length model of the rod considering the clearance of the moving pair is established.On this basis,the Archard wear model is introduced to quantify the influence of the motion cycle on the effective length of the rod.The sample size data of the rod under different motion cycles are obtained by monte carlo method,and the sample correlation coefficient is calculated.Then,the sample data of the rod under different motion cycles are reconstructed by Aholesky law.Combined with the reliability theory,the motion reliability of the mechanism is evaluated.Finally,the effectiveness of the proposed method is verified by taking the pantograph mechanism as an example.The results of calculation and analysis show that the correlation of rod sample data is enhanced due to the existence of kinematic pair clearance,and becomes more and more significant with the increase of kinematic pair clearance.Compared with the traditional analysis methods,the mechanism motion reliability index based on Cholesky rule has a certain degree of decline,which can provide a safer reference value for the reliability evaluation of practical mechanisms.