Experimental investigation and nonlinear modeling of steady arm installation defects in catenary–pantograph systems

Dynamic analysis of catenary–pantograph systems is an important engineering issue because it contributes to predicting current collection performance and understanding accident phenomena. This field has been active since around the 1960s, and many models have been developed and experimentally validated. More recently, installation defects and their effects on current collection performance have also been studied. However, experimental validation of models under defective conditions remains limited. In particular, installation defects in the steady arm, an important component of the system, have not been sufficiently investigated. Therefore, in this study, full-scale experiments and numerical analysis were combined to investigate the effects of a steady arm installation defect (SAID) on Shinkansen system dynamics. First, excitation tests were conducted by applying impulsive external forces to an actual catenary. The experimental results revealed that SAIDs exhibit nonsmooth nonlinear behavior. The validity and limitations of the linear catenary model were clarified through comparison with the experimental results. Full-scale running tests further showed that SAID-induced nonlinearity significantly affects contact wire uplift in the high-speed range. Subsequently, a bilinear stiffness model was introduced to represent a SAID, and its parameters were identified by minimizing the residual sum of squares between the excitation test results and simulation results. The developed model was also shown to reproduce transient responses observed in running tests with a SAID. These findings clarify the range of validity and the limitations of the linear model under conditions with SAIDs and provide a methodology for identifying the nonlinear characteristics associated with such defects. The findings of this study are expected to contribute to efficient maintenance based on digital technologies, the importance of which is increasing in response to the aging of railway infrastructure and the shrinking labor force.