Vibration analysis of uncertain spot-welded structures: experimental validation

Abstract

There are inevitable uncertainties in the properties of spot-welded structures due to variability in the positions and diameters of the spot welds. This produces uncertainty in the vibrational response. Ideally the analyst would like to predict this variability, but this raises the challenges of efficient computation of response statistics as well as practical quantification of the input uncertainty. This paper presents an experimental validation of a numerically efficient approach to the prediction of vibration response statistics, which involves a multi-point constraint spot weld model, component mode synthesis with characteristic constraint modes and a low-rank update theory; the method is described elsewhere. Measurements were taken on 108 single-hat profiles, subsequently joined in pairs by four spot welds to produce 54 double-hat profiles. The spot weld diameters and positions were measured. These are then used as input data for the finite element model. Measurements of natural frequencies, frequency responses, loss factors and mode shapes were taken. Spot weld location and diameter and the natural frequencies are seen to be well modelled by normal distributions, with some modes being strongly correlated. Agreement between the numerical predictions and measured results for the natural frequency statistics and the frequency responses are seen to agree well

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Identifiers

ORCID for N.S. Ferguson: orcid.org/0000-0001-5955-7477

ORCID for B.R. Mace: orcid.org/0000-0003-3312-4918

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