In Situ Imaging of Parachute Textile Micromechanics Under Tensile Load

Micromechanics of parachute fabrics under tensile loads are studied using in situ x-ray microtomography. Results are presented for two nylon textiles commonly used in parachute systems, MIL-C-7020H Type III and MIL-C-44378(GL) Type II. Textiles are subjected to incremental tension using a custom apparatus that loads the fabric radially, and the microstructure is imaged sequentially at steady load conditions. Microtomography images are processed using learning-aided segmentation and a custom processing pipeline that tracks the locations and morphological properties of individual tows on 3D datasets. Results are used to reconstruct tow microscale properties and meso-scale strains. Our findings reveal a direct relation between the fabric architecture and the meso-scale mechanics. Warp tow pretensioning during manufacturing is found to affect decrimping and the anisotropy of the textile strains. Areal porosity increase with tension is quantified, and a geometric model for pore opening under incremental load is validated.