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Modern fatigue analysis techniques, that can provide reliable estimates of the service performance of components and structures, are finding increasing use in vehicle development programs. A major objective of such efforts is the prediction of the field performance of a fleet of vehicles as influenced by the host of design, manufacturing, and performance variables. An approach to this complex problem, based on the incorporation of probability theory in established life prediction methods, is presented. In this way, quantitative estimates of the lifetime distribution of a population are obtained based on anticipated, or specified, variations in component geometry, material processing sequences, and service loading. The application of this approach is demonstrated through a case study of an automotive transmission component.

The incorporation of reliability theory into a fatigue analysis algorithm is studied. This probabilistic approach gives designers the ability to quantify “real world” variations existing in the material properties, geometry, and loading of engineering components. Such information would serve to enhance the speed and accuracy of current design techniques. An automobile wheel assembly is then introduced as an example of the applications of this durability/reliability design package.

A concise method for modeling nonstationary fatigue loading histories is presented. The mininum number of model parameters is achieved by fitting the variations in mean and variance by a truncated Fourier series. An autoregressive moving average (ARMA) model is used to describe the stationary component. Justification of the method is made by comparing fatigue relevant parameters obtained when subjected to the original and reconstructed histories. In spite of a relatively small number of parameters required, the model is shown to give good results that fall within the bounds predicted by the orginal history.

An exact approach to the aeroelastic spanwise lift distribution and divergence instability of swept (aft and back) uniform composite wing structures is developed in this paper. The approach based on the Laplace transform technique enables one to solve in a unified manner both aeroelastic problems. The analysis encompasses the cases of free and restrained warping models for the wing twist. Numerical results are finally presented to demonstrate the effects played by the fiber-orientation, ply lay-up, warping restraint and wing geometry both on the subcritical static aeroelastic response and on the divergence instability of composite swept wings.