Category: Thermo-Mechanical Material Modeling

The picture shown above is from a classic simulation of oblique impact of a copper rod.  This is a really interesting thermo-mechanical analysis where the impact event generates a lot of heat, and the heat in turn softens the mechanical properties.  There are also other classes of problems where friction can generate heat and in turn the heat changes the material properties.  There are already good resources (Example problem manual, training classes, papers) for metal plasticity based thermo-mechanical material modeling. 

What I want to discuss in this post is thermo-mechanical material modeling of elastomers and polymers.  This subject is covered a bit in our training class Modeling Rubber and Viscoelasticity with Abaqus course.  However, the class does not show how to construct this type of material model from test data. 

In preparing to teach a class prior to our 2015 SIMULIA Community Conference (SCC), I was able to find some test data from an interesting website, solidmechanics.org that was put together by Professor Allan Bower.   With Professor Bower's permission, I have put together some notes and a workshop example / demo for creating a thermo-mechanical material model for an elastomer/polymer material.  The basis for this example/demo comes from:

http://solidmechanics.org/problems/Chapter3_6/Chapter3_6.php         ;  then scroll down to problem 3.6.5

The type of material model to be discussed is that of Time-Temperature Superposition, or TTS.  This type of material model typically starts with an elastic definition based on either *Elastic or *Hyperelastic, plus viscous behavior specified by a Prony series (*Viscoelastic).   Time-Temperature Superposition is discussed in many books on viscoelasticity, I like the one by Ferry, Viscoelastic Properties of Polymers.   I should remind everyone that much of the work in this field was targeted at amorphous polymers above their Tg. In the narrated slides below, we review some of the basics around TTS, then describe the test data from Professor Bower's website, then proceed with a narrated explanation of calibration using an Excel spreadsheet.

Here is the narrated video of the slides in mp4 format (12 minutes long, 28 Mb) :  (the video will be sharper if downloaded)

Here is the narrated video of the Excel workshop in wmv format (23 minutes long, 53 Mb) :  (the video will be sharper if downloaded)

This work was performed with version 6.14 of Abaqus.  The attached zip file contains the slides (pdf format) and Excel file and a few sub-directories with the Abaqus and .psf files.  In the slides in the zip file I have also added a slide with references to a common application - modeling of the polyvinyl butyral layer in safety glass.  There are many published papers on this application, many showing work done with Abaqus.

Back to: Material Modeling and Calibration - An Overview and Curriculum