A kinematic approach to Kokotsakis meshes

13 years 4 months ago

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A Kokotsakis mesh is a polyhedral structure consisting of an n-sided central polygon P0 surrounded by a belt of polygons in the following way: Each side ai of P0 is shared by an adjacent polygon Pi, and the relative motion between cyclically consecutive neighbor polygons is a spherical coupler motion. Hence, each vertex of P0 is the meeting point of four faces. In the case n = 3 the mesh is part of an octahedron. These structures with rigid faces and variable dihedral angles were first studied in the thirties of the last century. However, in the last years there was a renaissance: The question under which conditions such meshes are infinitesimally or continuously flexible gained high actuality in discrete differential geometry. The goal of this paper is to revisit the wellknown continuously flexible examples (Bricard, Graf, Sauer, Kokotsakis) from the kinematic point of view and to extend their list by a new family.

Hellmuth Stachel

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