Size effects in plain-weave Astroquartz® deployable thin shells
The general scaling trend for brittle materials, in which the strength increases when the sample size decreases, is reversed in plain-weave laminates of Astroquartz® and cyanate ester resin. Specifically, both the shear stiffness and the compressive strength decrease for test samples with widths smaller than 15 times the wavelength of the fabric, and observations at the microscale explain this behavior. The derived scaling is applied to the analysis of a deployable thin shell forming a 90∘ corner hinge with five cutouts on each side. The cutouts leave narrow strips of material with width as small as one fabric wavelength, forming structural ligaments whose strength and stiffness are subject to strong size-scaling effects. A numerical simulation of the folding process followed by a failure analysis is presented, using two alternative material models and failure criteria. The size independent model predicts that the structure will remain damage-free after it is folded and deployed, whereas the size-scaled model predicts that failure will occur. The correctness of the size-scaled model prediction is verified by measuring localized damage in a physical prototype, using x-ray CT scans.
© 2021 by SAGE Publications. Article first published online: January 27, 2021; Issue published: August 1, 2021. This work was supported by a NASA Space Technology Research Fellowship, with Dr. William Doggett as mentor. The help of Professor Christian Franck, Department of Mechanical Engineering University of Wisconsin-Madison, and his research group in using FIDVC is gratefully acknowledged.
Accepted Version - Ferraro-Pellegrino_final.pdf