Manufacturing and testing of thermoplastic composite high load hinge

A composite hinge has been designed to replace an existing metallic hinge on an aircraft aileron. The new design aims to reduce the manufacturing cost while maintaining the operating loads and conditions. Thermoplastic composite hinges were produced from solvent-impregnated fiber fabric-reinforced polyetherimide prepreg. To get fully consolidated thermoplastic composite parts with high quality, optimum forming conditions such as forming temperature, holding time, and forming pressure were determined by an impregnation model. The final void content in the thermoplastic composite hinge was less than 0.2%. A special test rig was designed to test the hinges under the worst loading condition expected during operations. Composite hinges with different fiber orientation and flange/web thickness ratio were tested up to failure. All hinges behaved linearly up to the onset of the first crack growth in the tensile section. After this event, non-linear behavior was observed. The main failure mode observed in all hinges appeared to be delamination in the tensile section. The load at which first delamination started was found to be in the range of 15-17 kN, depending on the fiber orientation and flange/web thickness ratio in the hinges, and catastrophic failure was not observed up to the specified maximum load of 25 kN. The ultimate load expected during the operation of the metallic hinge was met by the thermoplastic hinges.