The Laplace multi-axial response model for fatigue analysis

•Loads with transients caused by obstacles are modeled.•The model is a natural extension of the Gaussian load model.•The model can be used to simulate loads for finite element software.•The ‘transient’ parameter can be estimated by the kurtosis of load.•The damage caused by environment relates to the value of the parameter.

This paper introduces means for fatigue damage rates estimation using Laplace distributed multiaxial loads. The model is suitable for description of stresses containing transients of random amplitudes and locations. Explicit formulas for computing the expected value of rainflow damage index as a function of excess kurtosis are given for correlated loads. A Laplace model is used to describe variability of forces and bending moments measured at some location on a cultivator frame. An example of actual cultivator data is used to illustrate the model and demonstrate the accuracy of damage index prediction.