The Analysis And Test Research Of Cracked Metallic Structure With Bonded Composite Patch Repair

In order to prolong the service life of aging aircraft and ensure aircraft safety, it need replace and repair damaged components. Bonded composite repair has been recognized as an efficient and economical method to extend the service life of damaged aircraft metallic structures. The method has been applied successfully in the aviation maintenance of some developed countries, and it has been primary stage in this field in China.The main work in this paper is as follows:In this paper, three-dimensional (3D) finite element analyses were performed to obtain the J intensity value of crack repaired by bonded composite patch by considering the 3D stress state of patch crack. Some valuable conclusions were acquired by thermalstatic mechanical loading analysis. And results were verified by the static tension testing. Cracked and repaired specimens were tested under static load.In the chapter III, a static mechanical loading analysis of the repair problem was made.The repair effect is compared with various type of repair and effect of residual thermal stress patch width thickness and thickness of adhesive layer.Comparing stress distribution between elastic and plastic under unrepaired and repaired.Comparing the crack face outline difference between unpatched and patched model.The J-integral value is variational alone the thickness, and the value of unpatchedside is much higher than that of patched side.Comparing J integral value between patched and unpatched model.The repair effect was compared with various type of repair parameters such as patch thickness Young's modulus and thickness Young's modulus of adhesive layer.In the chapter IV, a thermalstatic mechanical loading analysis of the repair problem was made. For the single side repair, the patch material having the maximum mismatch in the coefficient of thermal expansion with that of the crack aluminum plate provides the better damage tolerance capability for single-side crack in the panel. The repair effect were compared with various type of repair parameters such as thermal residual stress loading, temperature. The repair effects were compared with various type of patch materials such as Boron/epoxy Graphite/epoxy T300/5405, Glare in the thermalstatic mechanical loading.In the chapter V, all the specimen was prepared by my myself and all the operating process was practiced. Cracked and repaired specimens were tested under static load.In the last chapter, some ideas for aviation maintenance are proposed by using the theoretical calculation combining with the test results. It is maybe valuable in the engineering practice later.