COCOMAT - New design tools and guidelines for aircraft structures

Problem:

There is a large unemployed structural reserve capacity between the ultimate load and collapse. While plasticity is allowed in the design of metallic aircraft structures, it is not allowed in the design composite aircraft structures. To do so requires an accurate and reliable simulation of collapse.

Approach:

The COCOMAT (Improved MATerial Exploitation at Safe Design of COmposite Airframe Structures by Accurate Simulation of COllapse) consortium was formed, comprising 15 industrial, research and university partners from around the world. The objective was to develop a design scenario for curved stiffened carbon fibre reinforced plastic panels which allows for reductions in weight.

Solution:

The project comprised six areas of work, ranging from benchmarking existing knowledge, material characterisation and degradation studies, development and validation of new tools to predict collapse of structures under operating conditions, to the development of design guidelines and industrial validation.

ACS Australia engineers contributed to the benchmarking  study on damage modelling and structural analysis. A validated analysis methodology and software tool for analysing composite postbuckling structures was developed. It also contributed to the design and analysis of various specimens for experimental testing of the effects of defects such as impact and debonds. Other work included the development of an approach for assessing the robustness of a structure using stochastic techniques, which was applied to postbuckling panel designs.

Outcome:

The application of the new tools and design guidelines will be a considerably reduced structural weight without impairing the safety of aircraft.

The work generated a substantially extended data base on material properties and on collapse of undamaged and pre-damaged statically and cyclically loaded structures. In addition, the developed tools reduce the design and analysis time by one order of magnitude, substantially improving response-to-market time of industrial developments.

(Note: ACS Australia was established in 2008 by the Cooperative Research Centre for Advanced Composite Structures (CRC-ACS) for commercialisation of the expertise and technologies developed by CRC-ACS. All ACS Australia staff also work within CRC-ACS.)