Automotive fatigue Load Spectra: Modeling, Identification and Applications

<div class="section abstract"><div class="htmlview paragraph">Fatigue design is invariably of prior concern for the automotive industry, no matter of the evolution of the mobility market: at first because carmakers must stay compliant with general structural integrity requirements for reliability, notably applicable to the chassis system, then due to the endless competition for lightweighting in order to mitigate product costs and/or enhance vehicle efficiency.</div><div class="htmlview paragraph">In the past, this key performance was often tackled by basic reference load cases, making use of the simplest signal content, e.g. sinus functions, to practice constant amplitude loads on test rigs and for computations, respectively. Nowadays, full time series coming from proving ground measurements, or any corresponding virtual road load data computations, may be applied to feed complex vehicle computations for virtual assessment and complex test facilities for final approval, under variable amplitude loads. In between, the concept of load spectra (i.e. distribution of amplitudes with respect of their occurrences) is here highlighted as relevant and effective to manage the load/stress generation step of the fatigue design.</div><div class="htmlview paragraph">At first, a theoretical model is called from recent papers and detailed. Moreover, it is identified on several proving ground measurements, focusing on wheel force transducer signals. Then, a discussion on the parameters values allows to shape some general trends of the model, which is in return considered trustable for any further inference. This opens the way to two main applications: damage assessment as a function of the material/process of interest, and test acceleration making use of block-type schedules.</div></div>