What is the stiffness of a bent book?

TL;DR

This paper investigates the complex bending behavior of a layered elastic system resembling a book, revealing non-linear stiffness, hysteresis, and energy dissipation mechanisms that could inspire novel damping devices.

Contribution

It introduces a centerline-based nonlinear rod model for layered elastic plates with friction, accurately predicting experimental responses and elucidating dissipation over large deflections.

Findings

Enhanced apparent stiffness due to layering

Significant hysteretic energy dissipation

Model predictions match experimental data

Abstract

We study the bending of a book-like system, comprising a stack of elastic plates coupled through friction. The behavior of this layered system is rich and nontrivial, with a non-additive enhancement of the apparent stiffness and a significant hysteretic response. A dimension reduction procedure is employed to develop a centerline-based theory describing the stack as a non-linear planar rod with internal shear. We consider the coupling between the nonlinear geometry and the elasticity of the stacked plates, treating the interlayer friction perturbatively. This model yields predictions for the stack's mechanical response in three-point bending that are in excellent agreement with our experiments. Remarkably, we find that the energy dissipated during deformation can be rationalized over three orders of magnitude, including the regimes of a thick stack with large deflection. This robust dissipative mechanism could be harnessed to design new classes of low-cost and efficient damping devices.