Error Reduction for the Determination of Transverse Moduli of Single-Strand Carbon Fibers via Atomic Force Microscopy
Abstract
PeakForce Atomic Force Microscopy (AFM) Quantitative Nanomechanical Measurement (QNM) is utilized to measure the transverse fixC;ber modulus of single strand carbon xC;fibers to less than 5 error for eleven types of carbon xC;fibers, manufactured by Mitsubishi, Toray, and HEXCEL, with longitudinal moduli between 924-231 GPA, including export-controlled fixC;bers. A positive linear correlation between the longitudinal and transverse modulus with an R2=0.76 is found. Statistical and physical criterion for outlier removal are studied and established to improve the quality of data to exclude outlier measurement points in an image based on the peak force, adhesion force, and indentation depth. Statistical and physical criterion are also developed to exclude outlier images within the sample set. Pitch-based xC;fibers are found to exhibit lower measurement error than PAN-basedxC;fibers. Additionally, PAN fixC;bers exhibited no apparent modulus correlation whenthe Pitch xC;bers are excluded. Underlying reasons for this lack of correlation are explored, with the most likely reasons being the difference in long-range order in the fixC;ber microstructure and aging effects due to the different sourcing and storage methods used for the PAN xC;fibers. Low uncertainty characterization of the transverse modulus supports greater understanding of fixC;ber mechanical behavior, and would allow xC;fiber manufacturers to certify their fixC;bers in both the longitudinal and transverse axes. Additionally, it would improve the confixC;dence in engineering estimates used by industry and defense programs for transverse performance of carbon fixC;ber-reinforced composites.
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 26, 2021
- Accession Number
- AD1179442
Entities
People
- Joshua D. Frey
Organizations
- Air Force Institute of Technology