Designing an ideal deformation behavior of a bending-active gridshell based on rotating quadrilaterals

Author

SAKAI, Yusuke

Abstract

A bending-active gridshell is a curved surface elastically deformed from an initial flat grid composed of bending flexible members. The constructability of a gridshell is linked to both its grid pattern and slender beam profiles. A grid pattern composed of piecewise linear curves is difficult to be fabricated as conventional scissors bending-active structures due to many additional parts. We introduce a bending-active gridshell exhibiting anisotropic bending deformation modes in the out-of-plane direction. This deformation behavior, referred to as mode separation, improves the constructability of a gridshell. The grid pattern is specifically designed based on a tessellation of rotating quadrilaterals. An initial flat grid is fabricated as compliant mechanism. To measure the out-of-plane deformability of the present gridshell, we compare the eigenvalues associated with elastic deformation modes. Several examples demonstrate mode separation between the out-of-plane deformation modes. By carrying out large-deformation analysis, the deformed surface with the ideal mode is investigated. Moreover, by combining rotating quadrilaterals and diagonal lines, the generated curved surfaces exhibit more complex shapes than those with uniform rotating quadrilaterals. Gridshells fabricated by 3D printer are shown for validating the results of numerical simulation. Our gridshell may provide a new insight into the design of grid pattern for generating variable shapes of bending-active gridshells with ideal deformation behaviors.