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dc.contributor.authorGuest, Simon
dc.contributor.authorFowler, PW
dc.contributor.authorSchulze, B
dc.description.abstractBlock-and-hole polyhedra can be derived from a bar-joint triangulation of a polyhedron by a stepwise construction: select a set of non-overlapping disks defined by edge-cycles of the triangulation of length at least 4; then modify the interior of each disk by an addition or deletion operation on vertices and edges so that it becomes either a rigid block or a hole. The construction has a body-hinge analogue. Models of many classical objects such as the Sarrus linkage can be modelled by block-and-hole polyhedra. Symmetry extensions of counting rules for mobility (the balance of mechanisms and states of self-stress) are obtained for the bar-joint and body-hinge models. The extended rules detect mechanisms in many cases where pure counting would predict an isostatic framework. Relations between structures where blocks and holes are swapped have a simple form. Examples illustrate the finer classification of isostatic and near-isostatic block-and-hole polyhedra achievable by using symmetry. The present approach also explains a puzzle in standard models of mobility. In the bar-joint model, a fully triangulated polyhedron is isostatic, but in a body-hinge version it is heavily overconstrained. When the bodies are panels with hinge lines intersecting at vertices, the overconstraints can be explained in local mechanical terms, with a direct symmetry description. A generalisation of the symmetry formula explains the extra states of self-stress in panel-hinge models of block-and-hole polyhedra.
dc.publisherElsevier BV
dc.rightsAttribution 4.0 International
dc.titleMobility of symmetric block-and-hole polyhedra
prism.publicationNameInternational Journal of Solids and Structures
dc.contributor.orcidGuest, Simon [0000-0002-0152-6579]
dc.contributor.orcidSchulze, B [0000-0002-6272-4296]
rioxxterms.typeJournal Article/Review

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Attribution 4.0 International
Except where otherwise noted, this item's licence is described as Attribution 4.0 International