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The uncertainty in stiffness and damping of an automotive vehicle’s trim-structure mounts and its effect on the variability of the vibration transfer function

Abolfathi, A; O'Boy, DJ; Walsh, SJ; Dowsett, AM; Fisher, SA; (2017) The uncertainty in stiffness and damping of an automotive vehicle’s trim-structure mounts and its effect on the variability of the vibration transfer function. Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 10.1177/0954406217721724. (In press). Green open access

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Abstract

A large number of plastic clips are used in an automotive vehicle to connect the trim to the structure. These are small clips with very small masses compared to the structural elements that they connect together; however, the uncertainty in their properties can affect the dynamic response. The uncertainty arises out of their material and manufacturing tolerances and more importantly the boundary conditions. A test rig has been developed that can model the mounting condition of the clips. This allows measurement of the range of their effective stiffness and damping. Initially, the boundary condition at the structure side is replicated. The variability is found to be 7% for stiffness and 8% for damping. In order to simulate the connection of the trim side, a mount is built using a 3D printer. The variability due to the boundary condition on both sides was as large as 40% for stiffness and 36% for damping. A Monte Carlo simulation is used in order to assess the effect of the uncertainty of the clips’ properties on the vibration transfer functions of a door assembly. A simplified connection model is used in this study where only the axial degree of freedom is considered in connecting the trim to the door structure. The uncertainty in the clip stiffness and damping results in a variability in the vibration transfer function which is frequency dependent and can be as high as 10% at the resonant peaks with higher values at some other frequencies. It is shown that the effect of the uncertainty in the clips effective damping is negligible and the variability in the dynamic response is mainly due to the uncertainty in the clip’s stiffness. Furthermore, it is shown that the variability would reduce either by increasing or decreasing the effective stiffness of the clips.

Type: Article
Title: The uncertainty in stiffness and damping of an automotive vehicle’s trim-structure mounts and its effect on the variability of the vibration transfer function
Open access status: An open access version is available from UCL Discovery
DOI: 10.1177/0954406217721724
Publisher version: http://doi.org/10.1177/0954406217721724
Language: English
Additional information: This article is distributed under the terms of the Creative Commons Attribution 4.0 License (http://www.creativecommons.org/licenses/by/4.0/) which permits any use, reproduction and distribution of the work without further permission provided the original work is attributed as specified on the SAGE and Open Access page (https://us.sagepub.com/en-us/nam/open-access-at-sage).
Keywords: Uncertainty, variability, vibration theory, vibration transfer function, impedance-mobility approach, statistical analysis, automobile, Monte Carlo method, mid-frequency structural dynamics
UCL classification: UCL
UCL > Provost and Vice Provost Offices
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Mechanical Engineering
URI: https://discovery.ucl.ac.uk/id/eprint/1561270
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