Finite Element Simulation and Full Scale Component Testing to Evaluate the Static Strength of a Composite Wing

Composite structures have been successfully used for developing several primary aircraft structures. Several works on weight optimization of composite structures to gain weight and performance benefits have been observed worldwide. In the present study, composite wing of a two-seater trainer aircraft has been designed and developed using Just-in-time Prepreg (JIPREG) fabrication process. The composite wing consists of skins, a main load carrying spar, two shear attachment spars and transverse ribs. Skins, spar webs and ribs are made of sandwich construction with foam as core and glass bi-directional fiber composite as face sheet material. Main spar flange is made of monolithic carbon composite. As part of weight optimization exercise, thicknesses of wing sub-parts are optimized based on strength and stiffness criteria. The optimized design is evaluated through finite element simulation using MSC NASTRAN, for various critical flight and landing load cases to estimate the strains and deflections, followed by static strength test, carried out on the full-scale wing to meet the requirements of JAR VLA. The work focuses on the details of FE analysis predictions and various aspects of full-scale static strength testing of wing, such as test rig design and its validation through FE simulations, test instrumentation such as strain gauge, deflection gauge, and load-cell data monitored during the test for Design Limit and Design Ultimate load cases. Weight-optimized wing structure design was validated through both FE simulation and testing for compliance of the airworthiness requirements and flight clearance.