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Details of Grant 

EPSRC Reference: GR/R32147/01
Title: Mode Jumping In Post Buckled Stiffened Composite Aerostructures
Principal Investigator: Falzon, Professor BG
Other Investigators:
Researcher Co-Investigators:
Project Partners:
Finite Element Analysis Ltd Ministry of Defence (MOD)
Department: Aeronautics
Organisation: Imperial College London
Scheme: Fast Stream
Starts: 15 September 2001 Ends: 14 September 2004 Value (£): 65,974
EPSRC Research Topic Classifications:
Eng. Dynamics & Tribology Materials Characterisation
EPSRC Industrial Sector Classifications:
Aerospace, Defence and Marine Manufacturing
Electronics
Related Grants:
Panel History:  
Summary on Grant Application Form
The dominant form of airframe construction is characterised by a thin skin which acts as a membrane and forms the aerodynamic surface, stabilised under compression by the use of stiffeners. The development of carbon-fibre composite materials has enabled the design of lighter aircraft structures although their postbuckling strength has yet to be effectively utilised. Stiffened composite structures have been shown experimentally to support load beyond initial buckling although predicting this non-linear behaviour analytically is complicated by the observed phenomenon of such structures undergoing secondary instabilities. These manifest themselves as dynamic mode changes and may release enough energy to cause structural damage on first occurrence or, if repeated mode changes occur at lower energy levels, may give rise to fatigue problems.This is of particular concern to stiffened composite structures where stresses at the skin-stiffener interfaces increase dramatically after intitial buckling which may then exploit the relatively weak through-thickness strength of these interfaces. This proposal will highlight the limitations of current finite element methodologies in predicting these mode changes and will aim to develop robust numerical techniques for predicting this behaviour by combining implicit and explicit numerical procedures. These techniques will be assessed by simulating available experimental data and will be subsequently used to investigate the behaviour that stiffener geometry has on the postbuckling response of stiffened structures. A small set of panels, designed to undergo mode jumping will be manufactured and tested to further validate the developed finite element methodologies.
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Organisation Website: http://www.imperial.ac.uk