Topology Optimization of Composite Self-Deployable Thin Shells with Cutouts

Abstract

The paper presents topology optimization studies of selfs-deployable joints in thin-walled tubular structures. The joints are made entirely of ultra-thin, fiber reinforced composite materials. The objective of this research is to strategically position cutouts on the joints so that they can fold without failing, while maximizing the deployed bending stiffness. The optimal shape and position of cutouts are the results of concurrent topology optimization of these composite, thin-shell joints with geometrical non-linearities, due to their folding and self-deployable nature. Numerical methods to accurately detect failure are implemented and results from a novel level-set method for topology optimization are compared to results from classical parametric optimization and preliminary designs based on physical intuition.

Design and optimization of self-deployable damage tolerant composite structures: A review

“…Seffen and Pellegrino [213] reported that this case of loading promotes the deployment to occur along the same path, increasing the repeatability of the process. Later research [26,80,148,151,184,206,225,231,264,281], more focused on composite materials, further supports the results obtained on the behaviour of tape-springs and on the use of torque-angle curves to characterize the retraction of tape-springs, leading to their application in several studies.…”

“…More recently, Ferraro and Pellegrino (2019) [80] explored the use of a topology optimization approach to define the geometry of the cut-outs in a composite deployable corner joint. The adopted topology optimization method differs from the original concept proposed by Bendsøe and Kikuchi in 1988 [23], where the element of a material volume had their density changed depending on a given criteria (such as maximizing the stiffness).…”

“…The adopted topology optimization method differs from the original concept proposed by Bendsøe and Kikuchi in 1988 [23], where the element of a material volume had their density changed depending on a given criteria (such as maximizing the stiffness). Instead, two different approaches were used and compared in [80]: the first was the parametric optimization of the points defining a spline, and the second was a LSM approach. In the first case, the design variables were eight points that could move freely in a constrained space, defining the shape of a spline.…”

“…Failing to balance these two requirements leads to one of two situations: either the structure becomes too flexible, failing to meet the rigidity requirements necessary to operate, or the structure becomes too rigid, making it impossible to retract / fold without damage initiation. Due to its novelty, information regarding the design and optimization of deployable structures considering multiple requirements is scarce [77,79,80,147,[149][150][151]154]. In other fields of application of composite materials, the design methodologies have evolved significantly.…”

Effect of Gravity on the Scale of Compliant Shells

“…However, as the characteristic shell dimension increases, gravity (and its associated loading) becomes a hindrance to the adoption of thin shells as compliant mechanisms at the larger scales-the physical limit of compliance in the scaling of thin shells is found to be around 0.1 m.Biomimetics 2020, 5, 4 2 of 18 describe the large shape transitions of viruses [8], and of red blood cells [9], and are the mechanical system for some of the fastest repeatable plant movements [1]. Their flexibility allows the movement in engineered compliant structures such as hingeless joints [10], or active piezoelectric actuators [11]. All these flexible structures are elastically deformed, which makes them susceptible to undergo large stresses.…”