Patent ID: 11940266
Assignee: THE AEROSPACE CORPORATION
Field: Measurement (Instruments)
Classification: CPC G | IPC G

Claim 0:
1. A method for determining coefficient of moisture expansion (CME) values for materials, comprising:
placing two or more coupons in a gaseous environment with a target relative humidity, each of the two or more coupons comprising a flat substrate and a film of a material to be tested;
saturating or drying the two or more coupons in the gaseous environment;
during the saturating or drying, simultaneously measuring changes in curvature of the film over time using a laser interferometer and measuring changes in mass of the film over time for each coupon of the two or more coupons;
converting the changes in curvature in the measurements that occur out-of-plane with a uniform radius of curvature to a strain value for the two or more coupons;
determining the CME using the strain values as a fractional change in the strain value per unit mass variation from the measured changes in mass due to moisture absorption or desorption of the film for the two or more coupons; and
selecting a [best] lowest CME value of the determined CME values [for] of the two or more coupons, wherein
the changes in mass and strain values of the film are measured simultaneously on each coupon of the two or more coupons,
an amount of the material in the film is less than one gram (g), and
a test time in the gaseous environment is 24 hours or less.