Search

# Using the Abaqus Hysteresis Model

## Introduction to the Abaqus Hysteresis Model

In this article, I will show how to use the Abaqus *Hysteresis model. The specific focus is on when to use Hybrid elements. Note that this is the Bergstrom-Boyce model, which is discussed in more details in a theory article and a graphical article.

First note that the *Hysteresis model is not available in Abaqus/Explicit!

## High Poisson’s Ratio Materials

If we run an Abaqus/Standard simulation with element type C3D8 and the following material model:
```				```
*Hyperelastic, Yeoh
0.10, -0.05, 0.01, 0.05, 0, 0
*Hysteresis
6.4, 1.5e8, 7.5,-0.7, 0.05
```
```
Then we get the following error:
```				```
***ERROR: THE INITIAL BULK MODULUS OF 40.000 EXCEEDS 100 TIMES THE INITIAL
SHEAR MODULUS OF 0.20000 (THE INITIAL POISSON RATIO 0.49750 EXCEEDS
0.495) FOR THE HYPERELASTIC MATERIAL NAMED MAT. HOWEVER, A HYBRID
TYPE ELEMENT IS NOT USED. THIS MAY CAUSE CONVERGENCE PROBLEMS. IT IS
RECOMMENDED THAT YOU CHANGE THE ELEMENT TYPE TO A HYBRID ELEMENT;
HOWEVER YOU CAN ALSO CONVERT THIS ERROR MESSAGE TO A WARNING MESSAGE
BY SETTING THE ENVIRONMENT VARIABLE NONHYBRID_INCOMPRESS TO WARNING
OR BY ADDING *DIAGNOSTICS, NONHYBRID=WARNING TO THE INPUT FILE (NOT
RECOMMENDED).

```
```
If we switch to C3D8H elements, it instead fails with the following error message:
```				```
***ERROR: HYBRID ELEMENTS CAN BE USED WITH THE HYSTERESIS MODEL ONLY WHEN THE
ACCOMPANYING HYPERELASTICITY IS FULLY INCOMPRESSIBLE.

```
```
To fix this problem you need to make the hyperelastic model fully incompressible by setting D1=0 (instead of 0.05):
```				```
*Hyperelastic, Yeoh
0.10, -0.05, 0.01, 0, 0, 0
*Hysteresis
6.4, 1.5e8, 7.5, -0.7, 0.05

```
```
With this change and with hybrid elements, the simulation will run fine!

## Low Poisson’s Ratio Materials

For “low Poisson’s ratio” materials, for example:

```				```
*Hyperelastic, Yeoh
0.10,-0.05, 0.05, 0.11, 0, 0
*Hysteresis
6.4, 1.5e8, 7.5, -0.7, 0.05

```
```
The *Hysteresis model works just fine.

## Final note

In most cases it is better to use the Abaqus PRF model, for example the Yeoh-Power-Law Flow model, or the PolyUMod Three Network Viscoplasticity (TNV) model than the *Hysteresis model.

### Are Large Language Models Useful for Polymer Mechanics? (2023)

This article examines how useful ChatGPT and other LLM are for explaining polymer mechanics theories. Are these tools you should use?

### Graphical Explanation of Modern Polymer Material Models

In this article I explain how you can graphically visualize the rheological model in order to better understand how these models behave.

### How Important is the Bulk Modulus in FEA?

Investigation of how important the bulk modulus is in a FE simulation. Using MCalibration and Abaqus, I show that most of the time the bulk modulus has virtually no influence on the FE results.