Calculating SIF Of Cracked Metallic Panel Repaired With Composite Patch With MLPG Method

In order to extend the service life of aging aircraft and ensure aircraft safety, it is necessary to repair damaged components. Adhesively bonded composite repair has been recognized as an efficient method, which has definite background and important practice value to study the restraining efficiency of bonded composite to the cracked components.Based on the fact that no grids are needed to establish the test function of meshless method and the discretized equations are established based on the nodes independent of each other, the meshless method avoid the disadvantage of finite element method with the influence of complex meshing and elements distorting, thus has obvious advantage in dealing with the problems such as crack propagation and so on. The meshless local Petrov-Galerkin (MLPG) method is a new numerical method presented in recent years, and it is truly a meshless method because it doesn't need any element or mesh for the energy integral or interpolation. The MLPG is used to analyze the stress intensity factor (SIF) of metallic cracked panel witch is been repaired with composite patch. A new simple and practical numerical technique based on the MLPG method dealing with material discontinuity conditions is presented in this thesis, by which material discontinuity between the composite patch and the cracked panel is simply solved. A 3D program of the presented method is developed, and the validity and correctness of the new method are demonstrated by the coincidence of the results, respectively obtained by the new method presented in this thesis and the FEM, of two numerical examples. A method so-called element free direct displacement (EFDDM) is used to calculate the SIF of cracked panel. A cracked metallic panel repaired with a composite patch is analyzed by the method and the program developed in this thesis, and the distribution of SIFs along crack front is obtained. The consistent between the results obtained by means of the MLPG and the FEM demonstrates the correctness of the former. The simulation of crack propagation of cracked metallic panel repaired with a composite patch is comparatively easy by means of the presented method, and it may be too difficult to carry out by the FEM.