Nonlinear scaling effects in the stiffness of soft cellular structures

Area of Science:

• Materials Science
• Solid Mechanics
• Mechanical Engineering

Background:

• Cellular structures exhibit unique mechanical properties.
• Linear elastic theory often fails to predict behavior under large deformations.
• Microstructural architecture significantly influences material response.

Purpose of the Study:

• Investigate nonlinear scaling effects in cellular structures under large uniaxial tension.
• Determine the influence of cell size and distribution on structural stiffness.
• Compare experimental findings with predictions from linear elastic theory.

Main Methods:

• Fabrication of honeycomb-like cellular structures from silicone rubber.
• Experimental testing under large uniaxial tension using a bespoke fixture.
• Optical strain measurements for global and local deformation analysis.
• Finite element simulations to validate experimental results.

Main Results:

• Large stretching induces nonlinear scaling effects dependent on microstructural architecture.
• Structures with smaller cells exhibited increased stiffness compared to those with fewer, larger cells for the same material volume.
• Linear elastic theory did not predict the observed large-strain nonlinear behavior.

Conclusions:

• The microstructural arrangement of cellular structures critically impacts their nonlinear elastic response.
• Cellular structure stiffness under large strains is strongly influenced by cell size and distribution.
• A nonlinear elasticity framework is necessary to accurately model the behavior of these materials at large deformations.