Bayesian Sequential Experimental Design for Fatigue Tests

Abstract

Summary.A Bayesian sequential experimental design for fatigue testing based on D-optimality and a non-linear continuous damage model was implemented. The model has two asymptotes for the number of cycles to failure: the fatigue limit and the ultimate tensile strength. With the introduction and stochastic handling of these asymptotes, the D-optimal design accounts naturally for the whole range of reasonable testing levels. Sequential design ensures that all the available data is used efficiently while choosing the next test level.

Wärtsilä Digital Design Platform

“…As an example of this, we can take the thermal load on combustion engine components [8] which effectively dictates the lifetime of a given component. That lifetime prediction [10] is not a number in its own right but a result of a chain of simulations, going from fatigue and finite element analysis to a computational fluid mechanics combustion simulation which, in its turn, takes its input from a one-dimensional performance simulation. When looking at the inputs of that performance simulation, we are actually looking already at the high-level product requirements, such as fuel consumption targets.…”

Large bore engine connecting rod fretting analysis

“…In case of crack growth, the failure can be unexpected and catastrophic. The challenge in the fretting is that the phenomenon itself is a complex interaction of friction, wear and fatigue [3,13]. Propagation of fretting-induced cracks can be predicted by using fracture mechanics [2,12], but there is no generalized theory to predict surface damage.…”

Thermomechanical Fatigue Analysis of Cylinder Head

“…Multiple engine cycles are simulated to achieve a stabilized solution ( Figure 1). The lifetime estimation is made by post-processing the FE results with the Z-post software with ONERA fatigue damage model [4,12]. The fatigue model considers nonlinear accumulation of damage, taking into account the full stress-strain history.…”