Monitoring the integrity of filament wound composite structures such as solid rocket motors and liquid fuel bottles is important in order to prevent catastrophic failures and to prolong the service life of these structures. To ensure the safety and reliability of rocket components, they require frequent inspection for structural damages that might have occurred during manufacturing, transportation, and storage. The timely and accurate detection, characterization and monitoring of structural cracking, delamination, debonding and other types of damage is a major concern in the operational environment. Utilization of a sensor network system integrated with the structure itself can greatly reduce this inspection burden through fast in-situ data collection and processing. Acellent Technologies, Inc. is currently developing integrated structural monitoring tools for continuous monitoring of composite and metal structures on aircraft and spacecraft. Acellent's integrated structural monitoring system consists of a flexible sensor/actuator network layer called the SMART Layer, supporting diagnostic hardware, and data processing/analysis software. Recently, Acellent has been working with NASA Marshall Space Flight Center to develop ways of embedding the SMART Layer inside filament wound composite bottles. SMART Layers were designed and manufactured for the filament wound bottles and embedded in them during the filament winding process. Acellent has been working on developing a complete structural health monitoring system for the filament wound bottles including data processing tools to interpret the changes in sensor signal caused by changes in the structural condition or material property. A prototype of a filament wound composite bottle with an embedded sensor network has been fabricated and preliminary data analysis tools have been developed.

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A study was condticted to determine the optimal inspection parameters such as range and time for finding defects in carbon/epoxy composite panels using IR thermography imaging. The present paper presents an innovative method for automatically selecting these parameters for evaluating composites based on a series of finite-element models. Such finiteelement models of composite panels with fiaws at different depth locations were constructed a priori and analysed to estimate the optimal operating parameters. The optimal inspection range and time were identified in the contour plots obtained from the appropriate finite-element analysis results. A graphite epoxy composite panel with phantom defects at various depth locations was built, and experiments were performed using a thermographic system to verify and validate the proposed method.

Digital imaging techniques are applied to the measurement of surface displacement and strain at elevated temperatures. A simple surface preparation using high temperature paint together with a CCD video camera for digital imaging serve as the basis for the measurements. Mathemetical correlation of the surface intensity pattern between reference and deformed states is used to measure local surface deformation. The method is non‐contacting and full field. Displacement and strain measurements have been made at temperatures to 600°. Coefficients of thermal expansion of three metals have been measured using this technique and compared to strain gauge and handbook values. Limitations and potential extensions of the method are discussed.

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