Welcome to PolyUMod

Material Models

The PolyUMod® library is a library of advanced (and accurate) user-material models for finite element modeling of polymers, biomaterials, and other non-linear materials. Commercial finite element codes still lack the material models needed to accurately simulate many types of materials. Polymer FEM has developed a library of general purpose material models that cover virtually all polymer systems, including thermoplastics, thermosets, elastomers, foams, filled plastics, and biomaterials. The PolyUMod library also include specific models for particular formulations, such as fluoropolymers and UHMWPE.

The PolyUMod subroutines provide the FE user advanced material models as if they were built into the FE program. Engineers can perform very accurate FE simulations without becoming an expert in material model software development. All of the difficult development work has already been done!

FE Software

The PolyUMod library works with the following FE software


The material models in the PolyUMod library can predict the non-linear, time-dependent, anisotropic, viscoplastic response of all polymers. Here are predicted accuracies of 3 common polymers.

TN Model Accuracy for PEEK
PN Model Accuracy for HDPE
TN Model Accuracy for PTFE

Common PolyUMod Material Models

The PolyUMod library contains a large number of material models. The following table lists some of the more commonly used models.

The BB-model is a very powerful material model for predicting the non-linear viscoelastic response of elastomer-like materials. The BB-model is already a native material model in Abaqus and ANSYS, but the PolyUMod implementation of this model supports additional element types, temperature effects, and failure models.

The Bergstrom-Boyce model with enhanced Ogden-Roxburgh Mullins effect (BBM) is the same as the BB-model, except that the eight-chain hyperelastic Network A include a Mullins damage term.

The anisotropic BB-model with Mullins damage is an extension of the original BB-model in which the hyperelastic response is captured using the anisotropic eight-chain model.

The Hybrid Model (HM) was specially developed for predicting the large deformation, time-dependent response of UHMWPE. The HM is typically not as advanced as the Three Network (TN) model, which is also quite accurate for UHMWPE and other thermoplastics.

The Dual Network Fluoropolymer (DNF) model was specially developed for predicting the large-strain, viscoplastic reponse of Fluoropolymers. The model is based on three parallel networks and supports volumetric flow.

The Three Network (TN) model was developed for predicting the large-strain, viscoplastic reponse of generic thermoplastic materials (in a glassy state). The TN-model is an excellent generic model for predicting the response of many different classes of both amorphous and semicrystalline thermoplastics.

The micromechanical foam model (MFM) is an advanced model for predicting the time-dependent, non-linear large-strain behavior of polymer foams. The MF-model is unique in that it not only considers the viscoelastic response of the material but also explicitly takes into account the density of the foam and the initial pore pressure inside the foam.

The three network foam model (TNFM) is a material model specifically developed for thermoplastic materials that are available as a foam. It is a combination of the three-network model (TNM) and the microfoam model (MFM). The TNFM explicitly incorporates the effects of different reduced densities.

The Dynamic Bergström-Boyce (DBB) model is an advanced constitutive model specifically developed for predicting the time-dependent, dynamic, large-strain behavior of elastomer-like materials. This model is an extension of the BB-model.

The Silberstein-Boyce model (SB) was developed for predicting the large strain, time-, temperature-, and hydration dependent response of Nafion. This material is often used as a polymer electrolyte membrame (PEM) in batteries, solar cells and fuel cells. The material response of this type of material is similar to many other thermoplastics, except that it has a unusually strong dependence on the moisture level.

The Flow Evolution Networks (FEN) model was developed to obtain an advanced multi-network model that is similar to the Parallel Network Model, but more numerically efficient and easier to use. The FEN model is suitable for elastomers, thermoplastics, and other isotropic thermoplastic materials.

The Three Network Viscoplastic (TNV) model is a general purpose viscoplastic material model capable of capturing the experimentally observed behaviors of many thermoplastics, including time-dependence, pressure-dependence of plastic flow, pressure-dependent volumetric response, damage accumulation, and triaxiality-dependent failure.

The Parallel Network (PN) model is the most advanced material model in the PolyUMod library. Each network in the PN model can have an isotropic or anisotropic hyperelastic response in series with an isotropic or anisotropic viscoplastic flow element. Each element can have temperature dependence and damage evolution. The PN model also support more than 20 different failure and damage models.