Part Qualification Methodology for Composite Aircraft Components Using Acoustic Emission Monitoring

Shane Esola,Brian Wisner,Antonios Kontsos,Prashanth Vanniamparambil,John Geriguis

doi:10.3390/app8091490

Shane Esola, Brian Wisner + Show 3 more

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https://doi.org/10.3390/app8091490

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Abstract

The research presented in this article aims to demonstrate how acoustic emission (AE) monitoring can be implemented in an industrial setting to assist with part qualification, as mandated by related industry standards. The combined structural and nondestructive evaluation method presented departs from the traditional pass/fail criteria used for part qualification, and contributes toward a multi-dimensional assessment by taking advantage of AE data recorded during structural testing. To demonstrate the application of this method, 16 composite fixed-wing-aircraft spars were tested using a structural loading sequence designed around a manufacturer-specified design limit load (DLL). Increasing mechanical loads, expressed as a function of DLL were applied in a load-unload-reload pattern so that AE activity trends could be evaluated. In particular, the widely used Felicity ratio (FR) was calculated in conjunction with specific AE data post-processing, which allowed for spar test classification in terms of apparent damage behavior. To support such analysis and to identify damage critical regions in the spars, AE activity location analysis was also employed. Furthermore, recorded AE data were used to perform statistical analysis to demonstrate how AE datasets collected during part qualification could augment testing conclusions by providing additional information as compared to traditional strength testing frequently employed e.g., in the aerospace industry. In this context, AE data post-processing is presented in conjunction with ultimate strength information, and it is generally shown that the incorporation of AE monitoring is justified in such critical part qualification testing procedures.

Highlights

Current aircraft structural design and qualification methodologies require large amounts of testing in bottom-up type approaches that typically start at the coupon level and extend to full aircraft evaluation [1,2,3,4,5,6,7]
Acoustic emission (AE) was successfully applied to full-scale, composite, fixed-wing aircraft spars during structural strength qualification testing
Correlations between acoustic emission (AE) activity and applied load were made that allow for the in-depth structural integrity assessment beyond the data available from pass/fail, legacy aircraft component testing

Summary

Introduction

Current aircraft structural design and qualification methodologies require large amounts of testing in bottom-up type approaches that typically start at the coupon level and extend to full aircraft evaluation [1,2,3,4,5,6,7]. The prescribed assessment process is, costly and time consuming, which makes the adoption of new materials or design modifications difficult. This is especially challenging in the case of composite materials for which slight changes in manufacturing parameters can invalidate prior test data and require re-qualification of the material performance [8,9]. Once extensive coupon testing is completed, design limit loads are computed for specific critical components. In this process, safety factors are added to account for reliability and uncertainty.

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