A case study on fatigue life assessment of an electric bus bodywork

Abstract

Bus bodywork requires a thorough assessment of strength and fatigue life. The rise of battery-powered electric buses in the market brings new challenges due to the weight of the battery containers affecting the dynamic characteristics of the vehicle and the stress on its bodywork and chassis frame. When a manufacturer decides to develop a conceptually new vehicle, it does not initially have the precise input information necessary to assess the strength and fatigue life of the vehicle body. In particular, information about the future operating loads must be more or less estimated at the design stage of the structure and refinement is possible only after measurements with a vehicle prototype. This paper focuses on the fatigue life evaluation of the bodywork of a new articulated electric (battery) bus. The results are confronted with previous experience from the development and testing of the bodyworks of diesel buses and trolleybuses. Experimentally determined and statistically evaluated S-N curves of structural nodes welded from thin-walled profiles and measured stress spectra were used to estimate the fatigue life using the hypotheses of accumulation of fatigue damage. The findings resulted in recommendations to improve the operational reliability of a particular vehicle and provided challenges for future research. However, it should be noted that some of the findings and conclusions presented in this paper relate exclusively to the bodyworks of urban public transport vehicles and not to long-distance passenger transport vehicles