Notes on the ansys hyperelasticity course

link here Hyperelastic material behavior is ideally described as: significant nonlinear elastic deformation that is entirely recoverable.Examples of materials classified as hyperelastic include: rubbers, foams, and soft tissues.

The stress generated in a hyperelastic material is based on the strain energy function.

To fully characterize a hyperelastic material, the following modes of deformation are needed: uniaxial, biaxial, and shear.

The ratio of a hyperelastic material’s final length to its initial length is known as the principal stretch ratio.

Strain invariants exhibit these characteristics:

1) They do not change when the reference coordinate system is altered.

2) They remain constant across all deformation modes.

3) They can be expressed as functions of principal stretch ratios.

Stresses in hyperelastic materials are determined from the strain energy function, as per the second law of thermodynamics.

The simplest hyperelastic material model is the Neo-Hookean model.

The coefficients of the hyperelastic strain energy function are related to the initial shear and bulk moduli.

A distinctive feature of the Ogden foam material model is its capability to represent high compressibility, with deviatoric and volumetric terms closely linked.

Topics in Hyperelasticity

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How to Perform Curve-fitting for Hyperelastic Material Models — Lesson 1

•  Curve fitting is used to calibrate hyperelastic models based on experimental data.
•  It is advisable to use single element models when testing the material model.

How to Set Up Response Function for Hyperelastic Material Models — Lesson 2

•  The Response Function Hyperelastic option is designed to use the experimental stress-strain data directly during the constitutive calculation.

• The response function method requires that the experimental data fully envelop the entire strain range of interest and should ideally include the dominant stress states encountered in the actual application.

How to Handle Element Distortion Errors in Hyperelastic Materials — Lesson 3

• Ensure good mesh quality, which may include using elements less susceptible to distortion, using a mesh with appropriately shaped elements, or applying the loads in smaller increments.