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A Comparison of Two Source Characterisation Techniques Proposed for Standardisation
Abstract:
Automotive industry shows an increased tendency towards characterisation of vibration sources by independent quantities such as blocked forces and free velocities. Currently two independent ISO working groups propose standards for this source characterisation process. Both standards are still under development.
In this paper it is shown how the different approaches can be derived and compared using the general framework for Transfer Path Analysis (TPA). It is shown how one standard clearly relates to classical TPA methods (using interface forces), while the other standard adheres the component-based TPA principles (using blocked forces). Practical guidelines found in the standard proposals are reviewed, allowing for a qualitative comparison of the proposed procedures. To address typical problems regarding completeness of the interface, an addition is proposed that incorporates the use of 6-DoF Virtual Point forces and moments. It is shown how this approach can be applied to any force characterisation, improving the general usefulness of the found forces. A simulated numerical test case shows the procedure of both standards and discusses the added value of including rotational moments in the source-describing force vectors. An industrial application case demonstrates the application of the second standard with the addition of virtual point forces and moments, leading to perfect agreement with the on-board validation sensor.