Virtual development in the area of structural analysis is often divided in two different parts. First part is static analysis, second part is vibration analysis. For both parts the simulation is done by Finite Element (FE) analysis. In static analysis contact is the most frequently occurring nonlinear effect in mechanical engineering. Any assembly of parts contain one or more contact surfaces, where some parts are connected by bolts, rivets, or any other joint technology. Linear vibration analysis, based on modal methods, is defined for linear models, without contact, only. Methods are needed that derive a linear model from a nonlinear model with contact by taking into account the loaded state of the structure for the contact.
Integration analysis merges linear and nonlinear simulation by an automatic method. Connections at closed contacts are frozen. For some applications also the state of friction is taken into account to define damping for vibration analysis. A linear model for vibration analysis is the result of this method. This method will be demonstrated by two state of the art industrial applications:
- 1
A nonlinear engine model after assembly will be converted in a linear model for a modal based vibration analysis with subsequent frequency response analysis. The influence of taking into account the correct state of the contact will be shown. Optionally, an optimization of rib position at the linearized model can be done.
- 2
In brake squeal analysis different pressure levels have influence on the contact state and on the frictional forces. It will be demonstrated that the automatic process take into account those effects. The result dependency on several parameters and the advanced solution that solves the equations for a complete sweep over a rotational speed range will be shown.
The integration analysis allows the simulation of more detailed physics in the virtual development.