A Test Method to Assess the Foldability of Flexible Structural Materials

A coupon level comparative test method was developed to assess the foldability of thin flexible materials used in deployable structures. The subject materials support tensile and compressive loads; they are not cloth-like. The non-destructive method consists of a tensile stiffness test and a compressive buckling test and reveals changes in coupon properties that could result from locally extreme strains incurred during folding. The test is intended to provide a standardized means to compare changes in material systems or fabrication processes as flexible material development efforts continue. The method was applied to nine identical rigidizable composite coupons folded ten times. Five of the coupons were folded to a 4 mm radius and four were folded to a 2 mm radius. The results did not reveal a measurable change in coupon behavior from the pre-folded state.