Deriving the Compressed Accelerated Test Cycle from Measured Road Load Data

Validation of vehicle structure is at the core of reduction of product development time. Robust and accelerated validation becomes an important task. In service the vehicle is subjected to variable loads. These act upon the components that originate from road roughness, manoeuvres and powertrain loads. Majority of the body in white and chassis structural failures are caused due to vertical loading. Measured road load data in test track have variable amplitude histories. These histories often contain a large percentage of small amplitude cycles which are non damaging. This paper describes a systematic approach to derive the compressed load cycle from the measured road load data in order to produce representative and meaningful yet economical load cycle for fatigue simulation. In-house flow was developed to derive the compressed load time history. Different parameters and checks related to window length assessment, range cycle plot comparison for the base and compressed data is explained. Further to this potential damage approach was used to map the conventional static durability load-cases to block cycle fatigue to increase the confidence in simulation results. The complete exercise had helped to improve the quality and time to market with minimum mass addition.