Modeling Elastomer Compression: Exploring Ten Constitutive Equations

Area of Science:

• Materials Science
• Computational Mechanics
• Polymer Physics

Background:

• Hyperelastic materials like polyurethane elastomers are crucial in engineering applications.
• Accurate numerical modeling of their behavior under load is essential for design.
• Constitutive equations describe material response, but their effectiveness depends on parameter determination.

Purpose of the Study:

• To assess the performance of ten constitutive equations for hyperelastic bodies.
• To investigate the impact of different methodologies for determining material constants.
• To model the first compression load cycle of a 90 Sh A polyurethane elastomer.

Main Methods:

• Numerical modeling of hyperelastic material behavior.
• Determination of material constants using four variants: uniaxial tensile test (I), biaxial tensile test (II), planar tensile test (III), and combined tests (IV).
• Experimental verification of the numerical model results.

Main Results:

• Modeling results are highly sensitive to the chosen constitutive equation when constants are derived from uniaxial tensile tests (variant I).
• Determining material constants using biaxial tensile tests (variant II) yielded the most advantageous results across all evaluated constitutive equations.
• Variant IV (all tests) also showed good performance, but variant II offered a more efficient approach.

Conclusions:

• The methodology for determining material constants significantly influences the accuracy of hyperelastic material modeling.
• Biaxial tensile testing provides a robust basis for parameter identification in constitutive models for polyurethane elastomers.
• Careful selection of both the constitutive equation and the parameter determination method is critical for reliable numerical simulations.