Obtaining data and performing analyses
Component models of the vehicle with ERC and the ERC in an alternative test setup were obtained by measuring in DIRAC. For the purpose of performing a classical TPA, a model of the vehicle without the ERC was obtained in addition, also with DIRAC.
Configurations with virtual points including and excluding rotational DoFs – as well as a configuration with only 3-DoF measurement – were combined with operational data having the ERC ‘active’ to obtain blocked forces. The variously obtained blocked have formed the basis for the majority of analyses. Each set was used to synthesise an in-vehicle response for comparison with a validation signal.
The upside of using DIRAC
We used our measurement software DIRAC with a live connection to a PAK MK2 measurement system to generate high-quality component models. As all required quality information was live available, any potential measurement errors could be spotted and solved directly. This allowed for a “first-time-right” workflow resulting in component models with high-quality virtual point information. CAD models of the subframe and ERC were readily available for this project, resulting in a controlled placement of sensors and impact positions for the FRF measurements. Also, preparation of the measurement setup was done in DIRAC on forehand, not wasting valuable measurement time.
In the remaining analyses SOURCE was used. Since both programs have embraced the virtual point technology the transition from measuring to analysis was fast and seamless. Thanks to the flexibility in this process we were able to efficiently set up and compare TPA results using different interface setups (e.g. with and without rotational DoFs).