Analysis of the most important design parameters of the crank drive w.r.t. the acoustic sensitivity - analysis of influence of the crank shaft design

The acoustic emissions of the combustion engine contribute a main part to the pass by noise of a passenger car, which is the main focus of associated NVH activities.
Starting from an initial model of the crank shaft at first the CAD data has to be adapted for each variant (given in the analysis matrix). Afterwards an adapted finite element model will be generated including a suitable reduction process. As the setup of the MBS model was realized in previous projects, the adapted crank shafts representations can be implemented directly.
After model setup of all defined variants a nonlinear time integration to the steady state condition for a given speed will be performed. As a result, the bearing forces are present w.r.t. the changed parameters of the crankshaft.
Furthermore the strain energy of the elastic crank shaft model is analysed. The results are averaged (and peak hold) for one load cycle to allow for an overall statement, which regions are sensitive concerning the NVH behavior (due to large strain energy). For reasons of further investigations also the contribution of each eigenmode to the strain energy is calculated and weighted with the participation factor.
After the parameter variation, which is performed in time domain, the bearing forces, which are assumed to affect the NVH behaviour dominantly, are transferred into frequency domain including the resulting phase angle with respect to the crank shaft angle and the different variants are compared.