Embedding measured data within a computational framework for vibro-acoustic design

Lead Research Organisation: University of Salford
Department Name: Sch of Computing, Science & Engineering

Abstract

The design of products to achieve acceptable levels of noise and vibration is a major concern across a range of industries. In many cases there is a large trade off between cost and performance, and this means that achieving an efficient design is crucial to commercial success. In principle design optimisation can be achieved through testing and improving physical prototypes, but the production of a prototype is time consuming and costly. For this reason there is a pressing need for virtual design methodologies, in which computational models are used to produce a near-final design before a physical prototype is built. Computational models used for noise and vibration analysis must be able to predict the performance of the system over a wide frequency range, potentially ranging from low frequency vibration problems at several hertz to high frequency noise problems at several kilohertz, and this presents severe difficulties. High frequency motions require a very detailed computer model, and this leads to long run times that are not ideal for iterative design. Furthermore, the high frequency performance of a system can be very sensitive to small manufacturing imperfections, and hence the predicted performance may not match the performance of the actual system. These difficulties can be largely overcome by employing recent advances in noise and vibration modelling in which a technique known as Statistical Energy Analysis (SEA) is combined with more conventional analysis methods such as the finite element method (FEM) or the boundary element method (BEM); this approach is known as the Hybrid Method. The Hybrid Method leads to a very large reduction in the run time of the model, while also providing an estimate of the variance in the performance caused by manufacturing imperfections. However, this approach does not fully solve the prediction problem, as a further major difficulty remains: some components in a system can be so complex that it is not possible to produce a detailed computational model of the component, and hence some degree of physical testing is unavoidable. Frequently experimental measurements are used to validate a computational model, or to update the parameters in a computational model, but the requirement here is quite different: the measured data must be used to complete the computational model by coupling a representation of the missing complex component to the other parts of the model. This issue forms the core of the current research proposal.

The aim of the present work is to add "experimental" components to the Hybrid Method, and one way to do this is to model a component as a grey or black box: a grey box model consists of mathematical equations with experimentally determined parameters, while a black box model is based purely on measured input-output properties. These models must be capable of being coupled to either FEM, BEM, or SEA component models, and the project will address this issue. A major challenge is to determine the appropriate experimental tests and machine learning algorithms that are required to produce such models in the context of complex vibro-acoustic components. A second major challenge is to quantify the uncertainty in such models, and to include this uncertainty in the combined system model. The model must predict outputs that are useful to the designer, and such outputs include noise and vibration levels, together with uncertainty bounds on the predictions. In some cases "sound quality" rather than the overall noise level is of concern, and the project will develop techniques for the "auralisation" of the output of the combined model. A number of case studies will be developed with industrial partners to explore the application of the proposed approach.

The present research programme will produce an efficient and reliable vibro-acoustic "design by science" prediction tool that meets the needs of a wide range of industrial sectors.

Planned Impact

In the medium and long term the proposed research will benefit the environment by enabling design of quieter products with lower weight and reduced energy consumption. Quieter products are important because noise is known to impact negatively on quality of life and health so many people will benefit through quieter environments and workplaces, reduced stress and improved ability to communicate in private and public transport.
The main benefits though will be economic, benefitting partner companies directly and feeding into the UK economy. 'Design by science' is of major importance to the UK economy; around half our exports are manufactured goods in which design engineering plays a major role in, for example, automotive, aerospace, rail and domestic products etc. Companies working in the sector are able to generate wealth by selling products in global markets and major part of their work is to design for better performance and lower cost.

Nowadays rather than build physical prototypes, which is relatively slow and expensive, designers want to give themselves a competitive advantage by doing all their design virtually, with computer modelling. 'Virtual prototyping' has advanced enormously in the last decade or so, and even very complex performance parameters can be predicted. However, modelling of product sound is not as reliable as most other performance parameters. Some individual components can be modelled vibro-acoustically but others can't which leaves gaps in the overall model of the assembled product: with only a partial model of the assembly it is difficult or impossible to predict the sound of the product.

Is product sound important? Design engineering companies think so, for three main reasons. First, nearly all products cannot be sold unless they meet noise limits. Secondly, a product that sounds 'wrong' is likely to be returned even if it works perfectly and returns are very expensive for the manufacturer. Thirdly, sound is very important for brand image even to the extent that it can make or break the reputation of a product. So acoustic design is highly important for designers, but the risks are high because problems cannot be predicted until late in the design cycle when it may be too late to fix them economically.

The proposal aims to help the designers to pursue their virtual prototyping philosophy by using measured data to fill the gaps left by components that can't be modelled. With a full model of the assembled product, the product sound can then be 'auralised' to allow the virtual product to be heard. Because of the importance of product sound and the difficulty of modelling, the techniques should offer competitive advantages through reduced time to market and prototyping costs.

Two of the partners are important contributors to the UK economy in different engineering sectors: automotive (Bentley), high value domestic products (Dyson). The new techniques will be developed in conjunction with these companies to ensure that they generate a positive impact on their virtual prototyping developments and hence benefit the UK economy.

There are two other companies in the consortium both of which produce design tools: Bruel&Kjaer supply a vehicle simulator to the automotive industry which can be enhanced by incorporating measured data for vehicle components that can't be modelled. WaveSix produce software for vibro-acoustic prediction. The tools developed by these companies are expected to generate much wider impact by making the techniques available across the whole range of engineering companies.

We will also make data from our experiments available online together with worked examples to help other design engineering companies to adopt the techniques.

Publications

10 25 50

publication icon
Clot A (2019) Development of a hybrid FE-SEA-experimental model in Journal of Sound and Vibration

publication icon
Elliott A. (2017) Application of the Round Trip theory for the in-direct measurement of point impedance by air-borne excitation in 24th International Congress on Sound and Vibration, ICSV 2017

publication icon
Meggitt J (2020) A framework for the propagation of uncertainty in Transfer Path Analysis in Journal of Sound and Vibration

publication icon
Meggitt J (2020) Finite element model updating using in-situ experimental data in Journal of Sound and Vibration

publication icon
Moorhouse A. (2017) Using measured blocked forces to provide realistic excitation of virtual acoustic prototypes in 24th International Congress on Sound and Vibration, ICSV 2017

 
Description Methods to embed measured data within the framework of a hybrid vibro-acoustic model have been proposed and tested. This helps designers to build computer models - also known as 'digital twins' or 'virtual prototypes' - of complex engineering products like vehicles and domestic products to predict the sound they make without the need to build costly physical prototypes.
Exploitation Route Engineering designers will benefit from more reliable and complete models for vibro-acoustic response of mechanical equipment and vehicles. Suppliers of acoustics and vibration measurement systems will implement project findings into software driving their measurement systems, particularly related to measurement uncertainties
Sectors Aerospace, Defence and Marine,Construction,Digital/Communication/Information Technologies (including Software),Energy,Manufacturing, including Industrial Biotechology,Transport

 
Description B&K 
Organisation Bruel and Kjaer
Country Denmark 
Sector Private 
PI Contribution Expertise in automotive NVH
Collaborator Contribution In kind contributions to acoustic simulation hardware and software
Impact None so far
Start Year 2015
 
Description Bentley 
Organisation Bentley Motors
Country United Kingdom 
Sector Private 
PI Contribution Expertise in vibro-acoustics and specifically in characterisation of structure-borne sound sources.
Collaborator Contribution Funding for one PhD and several taught MSc students.
Impact One PhD thesis. Several MSc student project reports. Several small contract research projects. One unfunded and one funded EPSRC bid
Start Year 2011
 
Description Dyson 
Organisation Dyson
Country United Kingdom 
Sector Private 
PI Contribution The blocked force method formed an essential element in the construction of a Virtual Acoustic Prototype for a Dyson product.
Collaborator Contribution Dyson committed test facilities, test products and skilled engineering specialists to implement the method within the compnay.
Impact Banwell, G., Hopper, H., Moorhouse, A., Elliott, A., & Meggitt, J. METHODS FOR AURALISING SOUNDS WITH TONAL COM-PONENTS. ICSV Florence, Italy, 2015
Start Year 2014
 
Description Farratt Isolevel 
Organisation Farrat Isolevel
Country United Kingdom 
Sector Private 
PI Contribution Expertise in the use of blocked forces for prediction of building vibration for 3 year KTP (KTP010582)
Collaborator Contribution Expertise, funding and site access for KTP
Impact 1 international and 1 national conference papers
Start Year 2016
 
Description University of Cambridge 
Organisation University of Cambridge
Department Cambridge Institute for Medical Research (CIMR)
Country United Kingdom 
Sector Academic/University 
PI Contribution Expertise in vibro-acoustic measurement
Collaborator Contribution Expertise in vibro-acoustic modelling
Impact Non so far
Start Year 2010
 
Description Demonstration of novel Vehicle Simulator Technology developed during the EMBED project 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Industry/Business
Results and Impact The event included a demonstration of Vehicle Simulator Technology developed during the project given jointly by the University of Salford, Bentley Motors Ltd and Bruel and Kjaer to an international audience of senior automotive engineers. The conference website reported the following:
On the 30th of September and 1st of October 2019, Internect Ltd., hosted the 5th International Forum Automotive Acoustics & Vibration-NVH in Manchester, UK. Decision Makers, Heads of Departments and Senior Experts from OEMs, suppliers and research institutes from over 15 countries experienced a new, networking-intensive conference format. Case studies and presentations, interactive sessions, panel discussions, Q&A sessions, workshops, the evening get together as well as the exclusive visit and guided tour to the University of Salford's Acoustic Laboratory rounded up the premier automotive NVH international event with the largest OEM representation.
Year(s) Of Engagement Activity 2019
URL https://www.internect.ca/content/868/2019-/
 
Description New methods for predicting noise and vibration 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Industry/Business
Results and Impact Aim: the aim of the workshop is to introduce state of the art methods for the prediction of noise and vibration developed during recent EPSRC-funded research. Numerical and experimental methods will be presented in a tutorial style. New ways of integrating experimental and numerical vibro-acoustic models will be described and illustrated by practical case studies including an industrial case study to be presented by Dyson.
Applications: vibro-acoustic modelling and design, product design, building acoustics and vibration.
Who should attend: consultants, acoustic and vibration engineers, researcher in vibro-acoustic measurement and modelling. The techniques presented are relevant for applications including automotive, aerospace, buildings, domestic appliances, marine, offshore and others.
Year(s) Of Engagement Activity 2019
URL https://www.ioa.org.uk/civicrm/event/info%3Fid%3D434%26reset%3D1