Our customer had a problem: Series production was already running when they discovered that part of a conductor was fatiguing under certain conditions and could eventually break. This would result in outages and customer complaints, which of course they wanted to avoid.
Experiments and the experience of the designers had brought no measurable improvements, in as far as the observed outages did not seem to correlate with typical measured variables such as maximum current and static distribution of current peaks.
We were asked to create a “Joule heating” model using COMSOL Multiphysics, which calculated the current conductor with the power dissipation and thermal conduction across the entire component.
COMSOL Multiphysics permits measured data to be coupled to the finite element model as boundary conditions, so we were able to create a time series “time versus temperature” from the time series “time versus current”. This could in turn be used to calculate voltages which, using the Coffin-Manson relation, permitted predictions to be made regarding the expected lifetime depending on the current loading.
So that our customer could also work with the model by themselves in future, we put together a COMSOL Multiphysics Tutorial for them as well, where we passed on our tips and tricks.