Toe Load Detection and Test Verification Based on the Natural Frequency of Fastener Elastic Rod

Objective The insufficient toe load of the fastener elastic rod will induce loosening of the surrounding fasteners, aggravate the dynamic response between wheels and rails, affecting the service life of the track components. Compared with the missing and breaking of the fastener elastic rod, fastener elastic rod loosening is more difficult to be spotted by routine manual inspection, so the toe load detection method of the fastener elastic rods needs to be studied. Method Taking WJ-7 fastener elastic rod of high-speed railway as an example, a refined model of fastener system is established, the modal characteristics of fastener elastic rod under different toe load states are analyzed, corresponding relationship between the toe load of fastener elastic rod and the natural frequency is obtained, and a rapid non-destructive testing method for calculating the toe load by testing the modal frequency of elastic rod is proposed accordingly. The high-speed railway line at the track test base of a State Key Laboratory is selected as the test site, and the test verification of the detection method is carried out. Result & Conclusion Under different toe load states, the 1st modal shape characteristics of elastic rods all manifest as vertical vibration and torsion on both side legs of the elastic rod. The maximum absolute value of the difference ratio between the simulation value and the measured value of the elastic rod 1st order natural frequency is 3.24%, so the test method can be considered as effective.