By Geraint Jones
An Engineering Nonlinearity (ENL) Workshop on Modelling, Testing, Identifying and Exploiting Nonlinearities in Aerospace Industrial Structures took place in the Auditorium at Pegasus House, Airbus, Filton, Bristol on the 24th and 25th February 2016.
The event was co-organised by Sanjiv Sharma, Expert for Modelling and Simulation at Airbus and ENL Steering Committee member, and Jonathan Cooper, RAEng Airbus Sir George White Professor of Aerospace Engineering at the University of Bristol and an ENL Investigator. Around 50 attendees drawn from the ENL academic and industrial partners, including a strong representation from Airbus itself, listened to presentations and participated in workshops around the “Exploiting Nonlinearities” theme.
Day one’s theme was “Setting the Scene”. Delegates arrived for an excellent networking lunch, followed by a welcome and introduction from the day one chair Sanjiv Sharma.
Sanjiv outlined the aims of the workshop:
– To overview current needs for modelling, testing, identification of nonlinearities in the aerospace industry
– – To overview recent developments for modelling, testing, identification of nonlinearities in the university sector
– To explore future requirements for the above
– To explore where nonlinearities may be exploited in structural designs
and some suggested areas to consider during the breakout sessions:
– Levels of nonlinearity – strategies for modelling and analyses for different levels of nonlinearities
– Predictive virtual testing
– Uncertainty vs modelling / testing fidelity; Validation and Verification
– Types of structure and types of nonlinearity that are of interest
– Discussion of case studies
Morten Ostergaard, Airbus Senior Expert in Nonlinear Finite Element Analysis, gave the first technical presentation, an “Overview of Static Nonlinear FEA for Structural Analysis in Airbus”, which charted the evolving use and eventual acceptance of modelling in structural analysis and certification.
Ron Bates, Robust Design Specialist at Rolls-Royce, continued with a presentation on “Robust Design for Nonlinear Systems”.
Edoardo Menga of Airbus Operation SL, Spain, then spoke to “Dynamics and Vibrations” in an Airbus context.
The first day continued with a workshop – the attendees broke into two groups to discuss:
– Needs and Requirements
– Exploration of where nonlinearities could be exploited.
The group discussions yielded some excellent material regarding the requirements of industry in being able to model and hopefully explain on-linear behaviour, and some examples of potential exploitation of nonlinear effects and systems.
Day 2, chaired by Jonathan Cooper, focussed on Research Findings related to Engineering Nonlinearity.
David Ehrhardt of the University of Bristol opened, showcasing his work on ENL with regards to “Nonlinear Modelling and Identification”.
Dave Barton and Ludovic Renson, also of the University of Bristol, followed on with a presentation entitled “Experimental Continuation”, which Dave explained included looking to exploit and leverage ongoing advances in computation with respect to experimental research, in analogy with ongoing advances in modelling and simulation made possible by greater computing power and flexibility.
The next presentation was from Aurelian Grolet of Imperial College, on “Localised vibration in non-linear cyclic structure”, which generated much interest from the ENL team and the assembled audience in general.
Hamed Khodaparast of Swansea University continued with “Steady-state solution of Multiple-degree-freedom nonlinear systems using incremental nonlinear control parameters”.
The meeting then broke into groups for the second workshop of the meeting to discuss “Smart Testing vs Quantification by Analysis”. The groups then shared their discussions as the meeting drew back together.
Following an excellent buffet lunch, Jonathan Cooper gave the last presentation of the meeting, “Nonlinear stiffness for Loads Alleviation using Folding Wingtips”, showing an excellent potential development exploiting nonlinear behaviour.
The meeting drew to a close with the final group workshop “How nonlinearities can be exploited – identify / describe pertinent case studies”, which yielded some excellent possibilities for practical exploitation of nonlinear properties and behaviour.
All workshop outputs were written up by ENL Project Manager Geraint Jones, and are available on the ENL sharepoint site for ENL members. These outputs will be invaluable in maximising and leveraging the impact of the ENL project, both for Industry and Academia.
Jonathan and Sanjiv drew proceedings to a close by thanking everyone for coming.
Airbus’ Pegasus House, originally constructed in the 1930’s in the Art Deco style