Composite Structure Repair Tolerance And Continued Airworthiness Compliance Processes On Clvil Aircraft

Advanced composites have been widely used in the field of aeronautics for several decades. Once the composite aircraft was put into use, it must affect the operation if the repair issues remained unresolved. One of the key points is to determine whether to repair or not, and the boundaries of reparability, that is, the so-called repair tolerance. There are also some problems in airworthiness compliance processes and technology after restoration.This thesis conducts a study on the determination of repair tolerance of civil composite structures and the airworthiness compliance certification processes of repaired structures, which is on the basis of one part of the research of structural repair support technology in the COMAC Aircraft Maintenance Expert System.To begin with, according to damage analysis of composite structures, the influences of different types of injury, damage components, damage location and detection probability on the structural strength and stiffness are investigated. The minimum requirements for structural carrying capacity of damaged composite structures in flight or in temporary flight are analyzed by linear interpolation. The different repair strategy and safety index for repairing effect are also studied. Secondly, in the light of the degree of injury and mechanism of impact injury, structural analysis model for the most common impact injury is established .And the engineering calculation of compressive strength after impact is provided so as to estimate the residual strength degradation and remaining service life of damaged structures. Then, modeling of composite bonding repair is conducted and the repair tolerance quantification appraisal target is given on the basis of in-depth analysis of the repair indicators of Boeing Company. Lastly, the effect of repair economy on repair tolerance is briefly introduced.It also addresses issues related to repair-integrity and continued airworthiness compliance certification that will help to ensure its acceptability in this paper. Structural integrity is discussed in order to describe a process and give the relevant requirements for demonstrating compliance with the applicable airworthiness regulations. What's more, some specific technical requirements and approaches to support the continued airworthiness compliance certification are obtained.The study in this paper provides an engineering reference for the practical application of composite structural repair and could help the further work on repair design and analysis, which lay a foundation for the further research.