Evaluation of Vehicle Systems Structural Durability Using PSD Based Fatigue Life Approach

In current competitive environment automobile industry is under heavy pressure to reduce time to market. First time right design is an important aspect to achieve the time and cost targets. CAE is a tool which helps designer to come up with first time right design. This also calls for high degree of confidence in CAE simulation results which can only be achieved by undertaking correlation exercises.

In automobiles most of the structures are subjected to vibration from dynamic loads. All the dynamic road loads are random in nature and can be very easily expressed in terms of power spectral density functions. In the current scenario structural durability of the parts subjected to vibration is done partially through modal performance and partially though frequency response analysis. The only question that arises is what amplitude to use at what frequency and how to map all the accelerated tests dynamic load frequency spectrum to simulation domain. The paper describes a systematic and economical approach of mapping all the accelerated tests in a single PSD and further using it for vibration fatigue. In addition a good correlation of simulation results with the test data is presented for the PSD based approach.