S2E9

Destroy bistability in folded thin sheets by removing the singularity

Influence of assumed strain hardening relation on stress-strain response identification from indentation

Abstract:

Creased thin sheets exhibit bistability, with a pressed-through state possessing a localized elastic singularity. We experimentally explore the loss of bistability upon excision of the singularity and a surrounding region of material, varying the thickness and hole geometry. We examine numerical solutions of an inextensible strip model, varying hole geometry, crease angle and stiffness, and other factors, and find reasonable qualitative agreement with experimental bistability boundaries.

These phenomena are consequential to the mechanics and design of crumpled elastic sheets, developable surfaces, origami and kirigami, and other deployable and compliant structures.

Abstract:

Instrumented indentation tests provide an attractive means for obtaining data to characterize the plastic response of engineering materials. One difficulty in doing this is that the relation between the measured indentation force versus indentation depth response (P-h data) and the plastic stress-strain response is not unique. This talk will present the characterization of plastic stress-strain response using a Bayesian statistical approach by taking account of both P-h data and the surface profile after unloading. A variety of power law expressions have been used to characterize the uniaxial plastic stress-strain response of engineering materials, but the form that gives the best fit for a material is not known a priori. The influence of assumed strain hardening relation on the stress-strain response identification will also be discussed.