Imperial College London

ProfessorDavidEwins

Faculty of EngineeringDepartment of Mechanical Engineering

Distinguished Research Fellow
 
 
 
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Contact

 

+44 (0)20 7594 7067d.ewins

 
 
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Assistant

 

Ms Nina Hancock +44 (0)20 7594 7068

 
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Location

 

475City and Guilds BuildingSouth Kensington Campus

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Summary

 

Overview

Strategic interest in assuring improved structural performance of machines, vehicles and structures exposed to severe dynamic environments throughout their service lives. This goal is addressed by delivering advanced methods of prediction and measurement throughout the design, development and service phases of critical structures, primarily in the aerospace and defence industries. The overriding approach is to ensure a fusion of the most advanced test and analysis procedures in structural dynamics.

OVERALL RESEARCH GOALS

Current research focuses on advancing the structural dynamics technologies which enable the structures used in power plant, defence and other critical applications to be designed and operated at the required levels of safety, reliability and commercial advantage. To quantify these performance goals the concept of Structural Performance is established, whereby the management of undesirable and damaging consequences of structural vibration are set in a positive light by using proper management to minimise them, thereby ensuring high level of structural performance: guaranteeing specified periods of safe and cost-effective functional performance.

The technologies required to meet these goals comprise a combination of advanced simulation tools (modelling and numerical analysis) for design and equally advanced experimental and testing tools which serve to provide the necessary validation and verification confirmations demanded in advanced technologies

SPECIFIC APPLICATION AREAS

Most research is driven by the needs of the advanced aerospace industrial sectors, including the high-performance turbomachinery industry; various defence industries and aircraft and space industries. These products must have a reliably-predictable and cost-effective working life throughout which their functional performance can be called on at any time. These working lives are strongly determined by the nature and level of dynamic loading that is experienced in service and the resulting vibration levels that are generated. Hence the research focus is on methods of modelling and response prediction for the key elements and the testing which must be done to demonstrate in advance the reliability.

CURRENT RESEARCH THEMES

Current research interests are focussed on three main themes:

  1. Joint Dynamics. Addressing the urgent need for greatly improved methods of modelling, and thereby predicting and designing, the joints and interfaces which connect the many components in typical structural assemblies, and which clearly play a major role in determining the dynamics of most practical engineering structures. This topic is proving very challenging and new ideas are necessary to resolve the current uncertainties. It is possible that new joint design concepts will be necessary rather than ever-increasingly complex models for current joint designs (most have which not had their dynamic characteristics considered). An international Research Committee on Joint Modelling was established in the ASME and now oversees a flourishing community of research and applications in this area.
  2. Nonlinearities. Extending traditional structural dynamic modelling and testing approaches for industrial-type designs to accommodate the growing preponderance of non-linear behaviour. While there is a rich literature of advanced dynamic analysis for nonlinear systems, these tend to focus on idealised low-order models because of the significant enlargement of the analysis which nonlinearities demand. In real-world structures, many nonlinearities are likely to be highly complex, and necessarily demand an approximate nonlinear modelling approach for economic reasons. This is a fertile area where practical engineering considerations call for first-order simplifications to give insight into the phenomena, if not precise quantification of the details.
  3. Fusion of Test and Analysis. Refining the new philosophies to ensure that both the mathematical models that are to be used for design can be fully validated prior to the final design optimisation procedures are carried out and the qualification testing that is done to verify the finished products are fully advised by the design model. While model validation has already become relatively mature, there is a new initiative to apply the same fusion concepts in the reverse sense by using highly detailed models constructed for design of complex products to design the highly-expensive qualification/ endurance tests that are undertaken for product verification. Recent research on this topic has revealed dramatic improvements in this area and a new Community of Practice in Smart Dynamic Testing is currently being established.