Open Access

ARTICLE

Structure Health Monitoring (SHM) System Trade Space Analysis

by Salman A. Albinali¹, David R. Jacques²

1 PhD Candidate, Systems & Engineering Management, AFIT, WPAFB, OH, USA.
2 Associate Professor, Systems & Engineering Management, AFIT, WPAFB, OH, USA.

Structural Durability & Health Monitoring 2014, 10(1), 1-17. https://doi.org/10.3970/sdhm.2014.010.001

Abstract

An analytic approach to exploring the tradespace associated with Structural Health Monitoring (SHM) systems is presented. Modeling and simulation of the life cycle of a legacy aircraft and the expected operational and maintenance events that could occur is shown. A focus on the SHM system detection of a significant crack length and the possibility of False Alarm (FA), miss detection and mishap events is investigated. The modeling approach allows researchers to explore the tradespace associated with safe and critical crack lengths, sensor thresholds, scheduled maintenance intervals, falsely triggered maintenance actions, and mishaps due to missed detections. As one might expect, it was observed that setting the SHM system very conservatively (closer to safe crack levels) increases detection but causes a high number of FA events. On the other hand setting the SHM system threshold higher to tolerate a larger crack length reduces FA events but increases the number of Miss Detection events. Furthermore as cracks propagate to a greater length it was observed that Miss Detection events can lead to catastrophic failures. The analytic approach described herein allows one to determine an acceptable balance between safety of flight and acceptable FA rates. The novelty of this approach is providing a life cycle analysis for a legacy aircraft equipped with an SHM system with expected events (FA, Miss Detections) that could impact the life cycle and cost-benefit analysis. This was accomplished by combining the method used in MIL-HDBK-1823 and Paris’s model and integrating it into a life cycle model reflecting changing crack size and detection in every flight sortie until the end of the life of the aircraft. This enables users to estimate the frequency of event occurrences and the costs associated with these events, thus contributing to a more accurate life cycle cost (LCC) analysis for an aircraft equipped with an SHM system. While the current model is applicable to crack propagation in metallic structures, analytic expressions for sensor signal variation associated with other damage/structure types would allow the current model to be extended for those applications.

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Keywords

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