Researchers at the University of Illinois, led by Cutler Phillippe, have unveiled a groundbreaking study showcasing how nondestructive testing (NDT) through micro-CT scanning is transforming the understanding of stress impacts on parachute fibers. The findings, published in the American Institute of Aeronautics and Astronautics Journal in August 2024, highlight the potential for advanced modeling and experimental techniques to enhance parachute performance across various applications, from spacecraft deceleration to relief missions.
Traditional methods of assessing parachute performance relied on measuring permeability and tensile strength. However, advances in computing and imaging now enable sophisticated modeling of parachute dynamics, linking fabric porosity, microstructure, and canopy mechanics to overall performance. As Phillippe explained, “Modeling can reduce the cost, labor, and time needed to create mission-specific textiles, by connecting fabric porosity, microstructure, and canopy mechanics to overall performance. But, the models require high-fidelity experimental data for accurate validation.”
In this study, researchers applied radial in-plane loads to military-standard parachute textiles using a bespoke tensile testing apparatus and used x-ray micro-CT imaging to examine how microstructural variations influence tensile response. High-precision linear actuators controlled the displacement with 4µm steps, while the apparatus withstood loads up to 120lbf. Micro-CT imaging captured sub-micrometer details, and advanced tools extracted data on textile architecture, enabling a faster and more detailed characterization of materials.
Fabric samples were imaged at 1.9µm/pixel resolution using a 4× lens to ensure precise analysis. A 3D U-NET segmentation technique, borrowed from medical imaging, differentiated warp and weft tows in the weave structure. Semi-automated extraction techniques assessed dimensions, crimp angles, and pore sizes relative to radial stress, revealing critical insights into the material’s behavior under load.
“Our findings show that the anisotropic response of parachute textiles under planar loads is strongly influenced by manufacturing methods, pretension, and the composition of warp and weft tows in terms of fiber count and size,” Phillippe noted. Warp pretension accelerated weft decrimping under load, resulting in weft-axis strains approximately 10% to 20% larger than those along the warp axis.
These insights are vital for improving parachute assembly and performance, as the orientation of textile pieces influences overall properties. The research offers promising advancements for selecting safer, more efficient parachute materials, which can be applied in scientific, humanitarian, and recreational settings. “Choosing the best parachute materials is crucial for safety and mission goals. This research can inform models which will be used to identify promising candidate textiles,” Phillippe added.
Looking ahead, the research team plans to utilize microscopy imaging to explore how textile pores affect airflow and to image textiles under flow conditions to visualize 3D deformation. These developments promise further enhancements in parachute material screening, making manufacturing and applications more cost-effective and time-efficient.
This breakthrough underscores the potential of nondestructive testing techniques like micro-CT imaging to revolutionize not only aerospace textiles but also broader engineering and scientific applications.
