Research Of Repair Technology On Defects Of Helicopter Composites Typical Components

In the paper, three typical forms of composite laminate of [45/0/0/45], [45/0/45/0/45]and [45/0/45/0/45/0/45] with scratch and delamination were repaired by the methods of bonded patch repair, scarf repair and blind rivet repair, and the repair scheme had been established. In the bonded patch repair, inverted wedge and wedge patches were used. In addition, heating drying process of middle temperature and room temperature were used in bonded patch repair and scarf repair. The effect of repair method on bearing strength had been investigated in the paper. In addition, theory strength calculation of typical H-beam component of helicopter with delamination repaired using middle temperature and room temperature was done in order to predict the repair effect of bearing strength.In the paper, a new finite element modeling method was built by the Patran/Nastran software. Combined Maximal stress criterions with Tsai-Wu criterions, the simulated calculations of repaired laminates were done. The results showed that the repair effects of middle temperature conditions were better than that of room temperature. It was found that more than 80% tensile strength of the undamaged strength could be recovered by bonded patch repairs. The repair effects of inverted wedge patches were better than that of wedge patches. Except for 4 layers structures, compression and shear strength more than 80% of the undamaged strength could be recovered by scarf repairs. Compression strength more than 80% of the undamaged strength could be recovered by blind rivet repairs for 5 and 7 layers structures.The strength experiments were conducted on repaired laminates and specimens were made according to repair scheme. Tensile, compression and shear experiments were done to evaluate the effect of repair and testing strength data coincided well with the FEM calculated values and the error was less than 10%.The simulation results of the delamination damage repair of typical H-beam component showed that the biggest failure index of the H-beam was less than 1 at middle temperature and room temperature which indicated the mechanics performance of repaired H-beam could meet the usage requirements. The above research results will provide a base model to design and optimize the repair scheme for the composite material structures. Meanwhile, it will provide a theoretical basis for the fast repair after helicopter injury in battlefields and test sites.