Shape Adaptivity
The efficiency of structures can be improved by carefully controlling the deflected shape under load. The use of composite materials in shape adaptive structures offers unique possibilities by harnessing the extension-twist and bend-twist coupling properties of unsymmetrical or hybrid laminates.
ACS Australia personnel were involved in the development of optimisation routines to permit the design of shape adaptive structures. The development of coupled structural/hydrodynamic optimisation methods was a critical component of this project. This concept was demonstrated in the design, manufacture and test of a composite hydrofoil, where shape adaptivity improved the efficiency across the operational envelope.
This technology has the potential to be applied to a range of structural applications including marine propellers, aircraft propellers, wind turbine blades, aircraft wings and control surfaces.
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Robust Design
The complexity of composites can result in geometric and material property variation, affecting the overall behaviour of the finished structure. This uncertainty is not new; materials are not homogenous, geometries are never perfect, loads fluctuate and boundary conditions are never ideal. The use of single, deterministic values in design may lead to situations where engineers are unable to predict potential flaws during design with serious safety consequences.
ACS Australia’s personnel have developed Robust Design techniques to ensure that composite structures will be tolerant to unknown variations and imperfections. Algorithms were developed to quantify changes to the output  responses due to variation in the input variables. Robust Design aims to capture the possible responses that can potentially be encountered and reduce these responses so that unexpected failure can be mitigated.
The concepts were successfully demonstrated in the CRC-ACS contribution to the European Commission 6th Framework Project COCOMAT (www.cocomat.de). Robust Design can be applied to all aspect of composite design. Future research will allow improved predictions of impact damage tolerance, material degradation and load paths in multi-component structures. |
Impact Modelling
Composite materials are well-recognised as having unique energy absorbing properties. Taking advantage of these properties, or ensuring that impact events do not compromise structural integrity, requires considerable depth in understanding of these high-speed events.
ACS Australia’s personnel have not only concentrated on using the latest modelling techniques for accurate impact prediction, but also on accurate characterisation of material behaviour. A suite of characterisation tests developed in-house has minimised the number of assumptions required and provided a high level of model validation.
We apply this approach to entire composite structures (including fasteners and adhesives), and leverage our extensive knowledge in failure of composites components and assemblies to generate unusually high-accuracy predictions, in applications from aircraft bird strike to automotive energy absorption systems. This knowledge is being further developed, to enable the design and implementation of life-saving crash management systems for helicopters.
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