脉冲荷载激励下扣件弹条扣压力检测方法

Detection Method of Clamping Force of Fastener Elastic Rod Under Impulse Load Excitation

为了更准确检测出高速铁路扣件弹条扣压力不足,提出了利用脉冲荷载激励下扣件弹条模态特征来快速无损检测扣压力的方法。通过对不同扣压力状态下的扣件弹条进行力锤激励试验,获得相应的弹条模态参数,进而得到扣压力与弹条固有频率的对应关系,最后通过测试弹条模态频率推算出其扣压力。结果表明:标准安装状态下的WJ-7型扣件弹条在0~1200 Hz内共有两阶模态,分别为781.60、922.86 Hz;移动激励点得到的加速度导纳值有差异,但固有频率相同;不同扣压力下弹条第1阶模态振型特点主要为两侧肢的垂向振动,后肢承受较大扭矩;扣件弹条扣压力与弹条第1阶频率基本呈线性关系,实际线路中可通过测试弹条固有频率来得到扣压力。

In order to detect the insufficient clamping force of high speed railway fastener elastic rod more accurately,a fast nondestructive testing method based on the modal characteristics of fastener under pulse load excitation was proposed.Through the force hammer excitation test on the fastener elastic rod under different clamping force conditions,the corresponding modal parameters of the elastic rod were obtained,and then the corresponding relationship between the clamping force and the natural frequency of the elastic rod was obtained.Finally,the clamping force was calculated by testing the modal frequency of the elastic rod.The results show that there are two modes of WJ-7 fastener elastic rod in the standard installation state with the range of 0~1200 Hz,which are 781.60 and 922.86 Hz respectively.The acceleration admittance values obtained by moving excitation points are different,but the natural frequencies are the same.The characteristics of the first order mode vibration shape of the elastic rod under different clamping force are mainly the vertical vibration of the two limbs,and the hind limbs bear large torque.The clamping force of the fastener elastic rod is basically linear with the first order frequency of the elastic rod.In the actual track,the clamping force can be obtained by measuring the natural frequency of the elastic rod.