The Appraising Method Of Repair Tolerance On Delamination Damage Of Civil Aircraft Composite Laminates

Composite material is anisotropic, and there exists many uncertain factors during the process of manufacturing, using and maintenance, resulting in the delamination of the internal structure. Under compressive loading, delamination at less than its compressive strength load,may make the overall structure of composites become local buckling bring delamination propagation and failure. At the same time, the civil aircraft often works under the hot and humid environments for a long time, so the delamination of composites structure is inevitably influenced by moisture, temperature and hydrothermal coupling effect, which will further reduce the carrying capacity and service life of the structure. In this paper, by using finite element analysis software ABAQUS, the simulation analysis on the mechanical property under delamination damage and in hot and humid environment of the civil aircraft composite laminate structure are carried out. What’s more, the effect of the coupling of hydrothermal stress on the delamination under hot and humid environment is also studied.During the process of operation, when the damage of composite structure of civil aircraft occurs, then the repairing is necessary to restore its mechanical properties and meet the airworthiness requirements to ensure flight safety. The composite adhesive bonding repairing is widely used, and is the major repair technology for delamination damage. Under hydrothermal environment, the repair area of civil aircraft composite material may easily influenced by the coupling effect of moisture, temperature and load leading to the reducing of performance. In this paper, the simulation analysis on civil composite adhesive bonding repair structure is carried out using ABAQUS. The effect of repair degree, repair method on the recovery of the repair mechanical performance and the residual mechanical properties of the repaired structure under hot and humid environment and hydrothermal coupling stress have been studied, which can provides technical support for the repair of civil aircraft.This paper is focused on civil aircraft delamination damage in composite laminates. The research on the appraising method of repair tolerance of civil aircraft composite structure is carried out using the theoretical mechanics analysis and ABAQUS numerical simulation research. The residual mechanical properties of damage composite laminates and repair structure are studied by the method of mechanical simulation analysis. In the research,considering the repair process, maintenance personnel quality, detection efficiency andeconomic factors, and other limiting factors, through regional analysis of civil aircraft composite structure repair, the upper and lower limit of repair tolerance are determined. Then correct and reasonable repair tolerance of each parts of the composite laminates can be gained,which can provide technical reference and evaluation method for maintenance engineering analysis.