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FTIR Heat Damage Assessment on V-22 Wing Skin

FTIR Heat Damage Assessment on V-22 Wing Skin. Date: 08/22/2017. Justin Massey and Andrea Boxell Materials Engineering NAVAIR – FRCSW and FRCE. 2017 DoD Advanced Composite Maintainers TIM. NAVAIR Public Release FRCE 090-2017

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FTIR Heat Damage Assessment on V-22 Wing Skin

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  1. FTIR Heat Damage Assessment on V-22 Wing Skin • Date: 08/22/2017 • Justin Massey and Andrea Boxell • Materials Engineering • NAVAIR – FRCSW and FRCE 2017 DoD Advanced Composite Maintainers TIM NAVAIR Public Release FRCE 090-2017 Distribution A – “Approved for public release; distribution is unlimited”

  2. Carbon/Epoxy Incipient Heat Damage NDI • During thermal exposures a chemical change in the matrix can occur and results in a reduction of composite material mechanical properties (Incipient heat damage). • These chemical changes cannot be detected with traditional NDI techniques. (No delaminations or changes in hardness). • Diffuse reflectance FT-IR (DRIFT) has been determined to be one of the most promising NDI techniques. • FT-IR: Fourier Transform Infrared Spectrometry • Mid-IR Spectral Surface Analysis • Excites molecular vibrations with infrared light to determine surface composition. • Can be developed to detect chemical changes due to thermal damage in polymeric matrix. DISTRIBUTION A

  3. FTIR for Heat Damage Assessment • COTS handheld DRIFT was developed for inspection of C/Ep materials used on current fixed winged aircraft. • Agilent Technologies Flexscan 4200 FTIR: Handheld Portable diffuse reflectance FTIR unit. • Determines surface chemical composition changes from thermal exposure and correlates to calibration method and short beam shear test results in FTIR software. Mahalanobis distance used to ensure spectra fits calibration curve. • Portable handheld FTIR has been qualified for use on the F/A-18A-G & E/A-18G for composite heat damage inspections. • NAVAIR has a national team expanding capability to other aircraft and standardizing calibration method development. • IM6/3501-6 calibration method developed for thermal damage inspections on V-22 aircraft. This method was used for thermal damage inspection outlined in this presentation. DISTRIBUTION A

  4. Heat Damage Event • A V-22 RH nacelle was damaged by an engine fire. • The RH nacelle and all its components were damaged beyond repair and were scrapped. • Due to their proximity to the fire, the wing skin and flaperon needed to be evaluated for heat damage. • Material on all evaluated components was IM6/3506-1 composite. DISTRIBUTION A

  5. Evaluation Criteria • Selected FTIR calibration correlated surface chemistry to short beam strength and produced a Mahalanobis distance to verify that the scanned material fit the calibration curve. • The composite was considered heat damaged when there was a 10% reduction in shear strength. 10% reduction DISTRIBUTION A

  6. Wing Skin Evaluation • Identified 15 analysis locations on upper and lower wing skin including two locations of known good material (not pictured). Upper Skin Lower Skin DISTRIBUTION A

  7. Wing Skin Evaluation • Sanded each location to reveal the first ply of IM6/3501-6 material. • Wiped with acetone to remove hydraulic fluid prior to scanning with FTIR. DISTRIBUTION A

  8. Wing Skin Results • Suspected damage locations had similar SBS readings to known good locations. • All locations met the criteria (greater than 9.0 ksi) for no heat damage. • M-distances showed that all scans fit the calibration curve. DISTRIBUTION A

  9. Flaperon Evaluation • Originally identified 5 analysis locations on the flaperon. • Heat damage identified in 2 of the 5 locations so a larger area was sanded and a grid was used to map the damage. DISTRIBUTION A

  10. Flaperon Evaluation • Removed one ply at a time until heat damage was no longer detected. • Damaged region became smaller as each successive ply was removed. • No heat damage detected over the ribs. Ribs likely acted as a heat sink in those areas. DISTRIBUTION A

  11. Flaperon Results • Removed two plies over the entire inspection region (app. 18 in x 14 in) and two additional plies in a smaller region (app. 5 in x 2 in). • FTIR can’t be used on heavily contoured surfaces • Must be able to press the head flush with the surface to prevent light from reaching the lens and altering the spectra. • Became more challenging to press the FTIR flush with the surface as readings were taken closer to the leading edge of the flaperon. DISTRIBUTION A

  12. Conclusion • No heat damage was detected on the upper or lower wing skin. • Heat damage was detected on the flaperon. Two plies were removed over the entire inspection region with an additional two plies removed in a smaller region. DISTRIBUTION A

  13. Moving Forward • Determine final disposition of wing skin and flaperon. • Additional material testing to create more calibrations that can be used for evaluating other parts of the V-22. • Develop standard FTIR evaluation procedures for the V-22 for mapping and removing damage. DISTRIBUTION A

  14. Questions? ? DISTRIBUTION A

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