Fold Line Based on Mechanical Properties of Crease in Wrapping Fold Membrane

Folded thickness of a large space membrane is determined based on the mechanical properties of a crease in a wrapping fold to identify a fold line induced by the wrapping fold. Wrapping fold experiments are performed to examine the configuration of fold line in detail. The experimental results indicate that the fold line induced by the wrapping fold deviates from the target straight fold line because the folded thickness is not equal to zero. To determine the folded thickness, the mechanical properties of a crease in the wrapping fold membrane are examined analytically. The folded thickness and the configuration of fold line are identified by the theoretical analysis in terms of the wrapped length of fold line, the tensile force, the membrane thickness, the radius of center hub, and the creasing force applied before wrapping. The results of the theoretical analysis are verified using the experimental results. A fold pattern, which consists of the fold line obtained by the theoretical analysis, is proposed, and the high packaging efficiency is realized by the proposed fold pattern.