Quantum mechanics

Diagonal

Theoretical physics

Magnetic field

Poynting vector

Surgery

Energy (signal processing)

Inverse

Metamaterial

Classical mechanics

Torsion (gastropod)

Physics

Nonlinear system

Anatomy

Mathematics

Optics

Quantum electrodynamics

Geometry

Energy current

Medicine

Rhombus

Mechanics Research Communications

In an analysis presented in 1909, Poynting (page 546 of [1]) had shown that for finite elastic deformations, the lines of greatest extension and contraction are inclined to the diagonals of the rhombus into which a square is sheared. The implication of this finding was that when slender structures are twisted, they undergo elongation as experimentally verified by Poynting's measurements with wires [1]. While many theoretical analyses have shown the possibility of Poynting and reverse (inverse) Poynting effect [2], [3], [4], [5], [6], [7], measurements of such effects are rather sparse [8], [9], [10], [11]. We present here measurements of a highly nonlinear Poynting effect, including its reversal from positive to negative (elongation to compression) direction during torsion. Such atypical behavior is exhibited by a rather exceptional material system that has a pantographic internal structure. For this material system, the classical Cauchy-type continuum model fails and a 2nd gradient continuum model is necessary to describe many of its deformation behaviors.

Pantographic metamaterials show atypical Poynting effect reversal