Analysis of Miura-Type Folded and Morphing Sandwich Beams

Folded-core sandwich structures have previously been proposed as lightweight, thin-plate building elements. Such structures typically use a Miura-type core pattern and have an efficient load transfer behaviour, however cannot be used for deployable structures as the attachment of face sheets suppresses any core kinematic behaviours. This limitation can be overcome with patterned face sheets that preserve rigid-foldability and form a layered meta-material, here termed a morphing sandwich structure. The relative performance of folded and morphing sandwich structures is unknown, with few studies on the structural behaviour of either configuration. The following paper uses a new digital fabrication methodology to manufacture folded and morphing beam prototypes from 0.9mm thick steel plate. These are subjected to experimental three point bending tests to assess force-displacement behaviour and failure modes. A numerical finite element analysis is conducted to simulate the failure behaviour of the experimental beams. It is seen that the morphing beam has a 44% reduction in strength compared with the folded beam, thought to be attributable to face plate eccentricity and flexibility introduced by the morphing beam hinge connection detail.