Integrity Evaluation of Feature Level Test Specimen of an Aircraft Primary Composite Structure

It is well known to the aircraft designers that the design of structure using only metals or only composite materials can be realized with higher confidence level based on the database or tools available present in their aircraft design bureau. However, data availability for design of primary structural element/joint using metal, composites, and mechanical fasteners is minimal, and many of them are proprietary; moreover, they are depending on type of design. There is a need to design and test a feature level test specimen with appropriate boundary and loading conditions, which simulates behavior of full-scale component. Primary structural joint for actuator mounting on the composite fin has been considered for feature level testing. The purpose of the tests was to demonstrate the validity of the structural joint by applying static limit and ultimate loads. The feature level test specimen consists of composite and metal joints was successfully loaded to the ultimate design load without evidence of failure. The global behavior predicted by the finite element (FE) model of the test arrangement was in close agreement with the experimental results as evidenced by the strain and displacement results. The success of the testing program demonstrated the importance of feature level test in the design stage of primary composite structural joints of a civil transport aircraft.