Vibration Analysis of a Coupled Multibody Dynamic Model of a Contact Mechanics Roller Rig

This study develops a detailed multi-body dynamic model of the Virginia Tech Roller Rig (VTRR) using multi body simulation software package SIMPACK. The Virginia Tech Roller Rig, a single-wheel roller rig with vertical plane roller configuration, is a state of the art testing fixture for experimental investigation of wheel-rail contact mechanics and dynamics. In order to have a better understanding of the dynamics at the contact, dynamic behavior and interaction of various components and subsystems of the rig need to be understood. In addition, it is essential to make sure that the measurements are only due to particular subject of study and not any intermittent source of disturbance. Any unwanted vibration at the contact needs to be compensated in the data measurements. To this end, a fully detailed model of the rig including all the components is developed in SIMPACK. The coupled multibody dynamic model represents all the major components of the rig and their interactions. The multibody dynamic model is employed for conducting noise, vibration, harshness (NVH) analysis of the rig. An Eigenvalue analysis provides the modal frequencies and mode shapes of the system. The modal analysis predicts the first natural frequency of the rig to be approximately 70 Hz, providing a relatively high bandwidth for evaluating the dynamics at the wheel-rail interface. Only dynamic that could have higher frequencies than the rig’s bandwidth is wheel-rail squeal. The model is also used to evaluate the performance of the contact force measurement system designed for the rig. The results show that the contact forces can be estimated precisely using the force measurement system.