Expandable Structures Based on the Bennett Linkage

In 1903, Dr Geoffrey Thomas Bennett (FRS from 1914 till 1943) devised a 3-D mechanism that consisted of a chain of 4 rods connected by hinges making a skew quadrilateral in which the hinges are neither parallel nor collinear. In normal circumstances to obtain 1 degree of freedom in a rod-hinge loop 7 rods were required. Bennett used the fewest rods possible to build a useful mechanism.



We have identified a particular arrangement for many Bennett linkages so large motion structures can be created. All of the components move harmoniously during expansion. The arches and towers on display were created using the Bennett linkages as expandable units. They can be used as mobile towers and supports for rapidly assembles tents.