Takeshi Akita

Wrinkle Intensity Minimization Design of Space Membrane Structure

This study concerns a shape optimum design to minimize wrinkle intensity of a membrane under an area constraint. The wrinkle intensity proposed by one of the authors is obtained by eective decomposition of the total strain energy in a wrinkled membrane into elastic strain and apparent strain energy. The optimization problem is formulated as minimizing the wrinkle intensity under the membrane area constraint that represents the thrust requirement of a solar sail in terms of the membrane shape. The membrane shape is modeled by non-uniform rational B-spline (NURBS) curves and the curve-passing points are adopted as design variables. For an ecient optimization, the sensitivity of the wrinkle intensity with respect to the shape is evaluated by using the semi-analytical dierentiation method. Some design examples show that the optimization approach is eectively reduced the membrane wrinkle intensity. Additionally, a high convergence property is achieved regardless of direct implementation of the nonlinear finite element analysis during the optimization.

Stiffness Characteristics of Membrane Space Structures Supported by Booms

A systematic parametric study on the stiffness characteristics of compound space structures consisted of membranes and booms is presented. Using a tension field finite element code including membrane wrinkle effects, basic vibration characteristics of a square planar membrane structures are shown, and the effects of various conditions of applied tension between membrane and boom elements are discussed.© 2012 ASME

Membrane space structure with sterical support of booms and cables

Authors suggested a new structure combined with lightweight membranes and booms using convex tape considering its application as a space structure. . The larger membrane is preferred to get a solar effect from sails and power generation needs. In the past researches, we assumed a square shaped flat structure and studied the use of cables, positions of cables connecting between boom and membrane. In this paper, an additional studies about a steric membrane structure with booms and cables has been carried out to confirm a structural properties. We manufactured experiment model for verifying these properties, and also we confirmed about the same kinds of properties of hexagonal structure.