Tracking the moisture expansion of carbon/epoxy composite exposed to varying humidity

Abstract

The moisture expansion of composites exposed to humid air was investigated. Tests for moisture expansion were performed on carbon/epoxy laminates exposed to humid air of different relative humidity levels and temperatures. The expansion strain data were employed to derive the material's diffusivity and the saturated expansion strain. The result indicated that the saturated expansion strain is about proportional to the level of humidity and inversely proportional to absolute temperature. An algorithm was then employed to track moisture expansion of a laminate in air with varying humidity level based on the diffusivity and the saturated expansion strain. The theoretical predictions were confirmed experimentally.