Determination of Moisture Content in Composites by Dielectric Measurements
Abstract
In Task I of this study, three-ply graphite/epoxy laminates with sensors embedded at their midplanes were exposed to various hygrothermal environments. Moisture content versus time was determined by weight measurements at discrete times during each exposure condition. In addition, capacitance readings were measured by the sensors at those same times. The capacitance was then converted to percent change at each time period and compared with the laminate moisture content. From the measured weight gain data, an analytical least squares curve fit program was used to establish the moisture diffusion coefficients necessary to then analytically establish the moisture content midplane at the discrete weight and capacitance measurement times. This procedure established a relationship between capacitance and local moisture content. A similar procedure was used in Task II where the graphite/epoxy laminates were thirteen plies thick and six sensors were placed through the thickness. The local moisture content/capacitance relationship with these Task II specimens were evaluated and compared with the results obtained in Task I.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 01, 1979
- Accession Number
- ADA099639
Entities
People
- A. O. Kays