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Reliability Oriented Optimisation of Structural Replacement Strategies for Aircraft Structures

Final Report Summary - ROSA (Reliability Oriented Optimisation of Structural Replacement Strategies for Aircraft Structures)

Executive Summary:
Executive summary (this is section 1.1 on page 2 of Deliverable 2 in WP1 (Final Reporting) named "ROSA_Final_Progress_Report.pdf", submitted 26/04/2013):

The optimization of maintenance schemes for aircraft structures is a major technical and economic issue in the aerospace industry. There is a strong interest to further optimise and customize maintenance activities, aiming at reducing costs directly and indirectly associated with unnecessary inspections and replacement actions. Recent technical developments in Structural Heath Monitoring (SHM) have provided new possibilities for inspecting engineered structures in general. Knowledge of the “damage level” of the structure and forecasting of its development on a probabilistic basis allows the intelligent system to plan removal from service of the aircraft when the requirement for maintenance is specifically justified

The methodology and the corresponding codes developed in the ROSA project facilitate the quantification of the impact of SHM information on maintenance planning and the optimization of the life-cycle costs. The framework developed enable the quantification of the effect of changes in the design of the structural components as well as the SHM design on the inspection / maintenance cost and consequently the overall life-cycle cost. All relevant models for the problem description have been presented, developed and implemented into a code. Main achievements of the ROSA project are summarized as follows:
• A mechanical meta-model for the description of the damage growth on stiffened composite material due to different impact scenario has been identified and implemented.
• A procedure for the inclusion of the monitoring system has been investigated. Models for the probability of detection and the receiver operating characteristic have shown to be essential in the perspective of the Bayesian damage update, at the basis of this report.
• The method for the evaluation of the capacity loss due to the damage detected by the monitoring system can be extended in order to include an alarm system for decision support.
• Complex structures, as the aircraft wing in final report, can be easily handled by the method, accounting for simplified structural effects on the element capacity.
• The ROSA strategy has been implemented for specific models but it can easily be adapted to more complex models, due to the modularity of the methodology.

Sensitivity analysis has been presented by changing the most relevant parameters. It has been shown that the quality of the monitoring system, expressed by the Receiver Operating Characteristic (ROC) curves is central to the optimization of the optimal interval between consecutive inspections.
The expected life-cycle cost analysis has been presented. The analysis evidenced that the probability of false alarm of the structural health monitoring systems plays an essential role in the total expected maintenance element cost.

The theory has been implemented in standalone a code and details, examples of runs and results have been provided. The possibility of interfacing the code with the software Strurel has been examined and conceptual solution has been given.

Project Context and Objectives:
Note: The text editing facilities in this online field do not allow to enter equations or graphics.
Therefore please refer to Deliverable 2 in WP1 (Final Reporting) named "ROSA_Final_Progress_Report.pdf", submitted 26/04/2013
and there to
Section 1.2 "Project context and objectives" (pages 3 & 4).

Project Results:
Note: The text editing facilities in this online field do not allow to enter equations or graphics.
Therefore please refer to Deliverable 2 in WP1 (Final Reporting) named "ROSA_Final_Progress_Report.pdf", submitted 26/04/2013
and there to
Section 1.3 "Description of the main S&T results/foregrounds" (pages 5 to 13).

Potential Impact:
Note: The text editing facilities in this online field do not allow to enter tables or graphics.
Therefore please refer to Deliverable 2 in WP1 (Final Reporting) named "ROSA_Final_Progress_Report.pdf", submitted 26/04/2013
and there to
Section 1.4 "Impact" (page 14),
Section 2 "Use and dissemination of foreground" (pages 15 to 19).
Section 2 also contains the tables in Section A and Section B mentioned below under item 4.2.
List of Websites:
No project specific website was generated in the rather small ROSA project.