Abstract
Attachments affect the dynamic response of an assembled structure. When engineers are modelling structures, small attachments will often not be included in the “bare” model, especially in the initial design stages. The location of these attachments might be poorly known, yet they affect the response of the structure. This paper considers how attachments jointed to the structure at uncertain points, can be included in the dynamic model of a structure. Two approaches are proposed. In the time domain, a combination of component mode synthesis, characteristic constraint modes and modal analysis gives a computationally efficient basis for subsequent analysis using, for example, Monte Carlo simulation. The frequency domain approach is based on assembly of frequency response functions of bare structure and attachment. Numerical examples of a beam and a plate with a point mass added at an uncertain location are considered and predictions compared with experiment results.
Highlights
In the initial design stage in particular, a model of the structure is often incomplete, with there being various additional componentry of various forms, referred to here as attachments, being added later, or maybe not included at all in the numerical model
This paper considers how the effects of these attachments might be included in the model and how they affect the dynamic response
Concluding remarks The paper discussed the influences of attachments located at uncertain points on the vibrational response of the structure
Summary
In the initial design stage in particular, a model of the structure is often incomplete, with there being various additional componentry of various forms, referred to here as attachments, being added later, or maybe not included at all in the numerical model. Attachments play an important role in complex structures, for example bundles of wires in cars or aircraft, small control and sensing boxes in engines etc. Normally small attachments will not be included in the “bare” mode. The location and properties of attachments might be poorly known at the beginning of the design process, and they are often fitted later. These uncertain attachments produce uncertainties in the dynamic response of the assembled structures. They might affect change the behaviour of the structures significantly and be a detrimental influence on the response of the products, such as higher noise or vibration levels. This paper considers the case where the properties of the attachment are known, but the points on the main structure to which it is attached are uncertain
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