Simulation Analysis of Equibiaxial Tension Tests for Rubber-like Materials

Area of Science:

• Materials Science
• Polymer Physics
• Mechanical Engineering

Background:

• Equibiaxial tension is crucial for characterizing rubber-like materials.
• Existing methods include inflation, planar, and radial tension, but their accuracy and comparability are unaddressed.
• Hyperelastic electroactive polymers (EAPs) require precise mechanical characterization.

Purpose of the Study:

• To model and investigate the experimental accuracy of three equibiaxial tension methods for EAP membranes.
• To analyze the impact of apparatus and specimen parameters on test performance.
• To propose a tensile efficiency metric for assessing deformation uniformity.

Main Methods:

• Finite element method (FEM) modeling of inflation, equibiaxial planar, and radial tension tests.
• Simulation of EAP membrane behavior under various test conditions.
• Development and application of a tensile efficiency metric.

Main Results:

• Inflation tension accuracy depends on sample point location; deformation is limited (λ ≈ 1.9).
• Equibiaxial planar tension with single-corner-point tension achieved low stress errors (2.1% at λ = 4).
• Radial tension with 24 cuts and a 5 mm hole yielded minimal stress error (3.83%); tensile efficiency is influenced by cuts and hole size.

Conclusions:

• Accurate characteristic curves for inflation tension require specific sampling points.
• Equibiaxial planar and radial tension methods can be optimized for uniform deformation and reduced stress errors.
• Findings provide guidance for selecting and designing equibiaxial tension tests for EAPs.