Reliability and Sensitivity Analysis of Multibody System Due to Uncertainty Parameters: A Case Study of Addis Ababa Light Rail Transit (AALRT)

Abstract

A multibody system is one of the complex mechatronic system whose dynamic performance is influenced by its connected components and the mechanical structure. However, during the service life, the system is subjected to degradation of different components whose conditions may greatly impact the vehicles running characteristics like stability and reliability. The suspension system is one of the key systems which ensures that better and reliable running behaviors are achieved and hence any uncertain changes in its performance characteristics becomes of significant interest and must be treated with utmost attention. This research presents a relevant study on how suspension system degradation affects the dynamic performance and reliability of multibody rail vehicles and provides a model which can be applied to evaluate the performance of the vehicle at various levels of suspension design parameters. The vehicle is modelled using SIMPACK dynamic software, incorporated with track irregularities from maintenance data and using matlab to estimate various levels suspension design parameters. The dynamic performance of the vehicle is evaluated by using dynamic indexes like derailment coefficient and vibration sensitivity to assess the level of reliability and sensitivity of the vehicle. The results showed that the running safety reliability is more sensitive at low values of damping and stiffness of the primary suspension and stability is achieved as they increase while vibration sensitivity increases with increase in damping and stiffness values of both primary and secondary suspension. Furthermore, secondary suspension damping and stiffness greatly influence vibration sensitivity as opposed to primary suspension damping and stiffness which exhibits little influence on vibration sensitivity hence secondary suspension damping exhibits the greatest influence on vibration sensitivity while primary suspension stiffness exhibits the least influence on vibration sensitivity.