CONTRIBUTION TO COMPOSITE 'T' BEAM DESIGN IN INDUSTRIAL ENVIRONMENT BY USING THE GRID TECHNIQUE

The paper focuses on the advantage to use a full-field technique when designing a part in composite materials. The actual structure is a composite beam with a 'T' cross-section which is intended to replace a similar beam made of light alloys and acting as an aircraft wing stiffener. The interest to use advanced composites here is to save weight. Moreover, composites should also reduce the component cost, therefore a solution based on preform injection moulding process has been selected. Since the overall shape of the beam was previously fixed, the main question was to select the fibre preforms and the way to design and assembly the preforms to reach acceptable properties. Firstly, a reference tensile test on 'T' shaped beam specimens is developed to compare the various solutions. The test should be simple enough but representative of the main loading of the part. Simplicity and flexibility of the testing approach are required when different solutions are to be investigated at the beginning of the design process. However, any rational comparison of structural performances have to be based on well-defined mechanical variables leading to quantitative data with uncertainties. Usually, industry is interested in overall quantities such as the stiffness and strength of the structure, those quantities being difficult to define accurately. The component part being complex and the goal being the optimisation of it, there is a need for more accurate characterization such as the localization of the first macro-damage. Obviously, the utilization of full-field methods would be both efficient and time saving.