Hybrid Model for UHMWPE

The hybrid model is a material model that was developed for ultra-high molecular weight polyethylene (UHMWPE) used in total joint replacements [1-8]. Information about the development and use of the Hybrid model has appeared in the open literature. [1-8]

Exponent has decided to release a free LS-DYNA3D user subroutine for the Hybrid Model under a General Public License summarized below. This user subroutine is made available on this website free of charge to the orthopedic research community. This implementation is documented in a conference paper, which is available on www.uhmwpe.org [7]

Aside for providing a link to this conference paper, Exponent does not provide technical support for the installation and use of the user subroutine with LS-DYNA.  

Exponent provides consulting services related to the use of Hybrid model. For more information please contact Dr. Steve Kurtz at skurtz exponent.com.


Hybrid model version HMV3 as of December 3, 2008 

Copyright (c) 2000-2008 Exponent, Inc. 
Jorgen Bergström, Anton Bowden, Erin Oneida 


This program is offered "AS IS". Any use of this program is entirely at the user's own risk. Any output from this program is intended for informational, research and evaluation purposes only. 

For licensing information, please contact: Steve Kurtz at skurtz@exponent.com 

All bug reports and technical questions may be sent to: Erin Oneida at eko4@cornell.edu 


This program is free software; you may redistribute it and/or modify it under the terms of the GNU General Public License Version 2.0, 1991, as published by the Free Software Foundation Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA (http://www.gnu.org/licenses/old-licenses/gpl-2.0.html). 

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY, NONINFRINGEMENT, or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

To Download a FREE copy of the LS-DYNA3D User Subroutine of the Hybrid Model.

1.  READ: Using the Augmented Hybrid Model UMAT Code (PDF)

2.  DOWNLOAD: LS-DYNA3D user subroutine of the Hybrid Model (Zipped Fortran file)


Between July 1, 2000 and August 31, 2009, model development was supported by an R01 grant from the National Institutes of Health, AR47192, entitled, “Constitutive Model for Polyethylenes in Joint Components.”


1. Bergström JS, Kurtz SM, Rimnac CM, Edidin AA. Constitutive modeling of ultra-high molecular weight polyethylene under large-deformation and cyclic loading conditions. Biomaterials 2002;23(11):2329-2343.

2. Bergström JS, Rimnac CM, Kurtz SM. Prediction of multiaxial mechanical behavior for conventional and highly crosslinked UHMWPE using a hybrid constitutive model. Biomaterials 2003 Apr;24(8):1365-1380.

3. Bergström JS, Rimnac CM, Kurtz SM. An augmented hybrid constitutive model for simulation of unloading and cyclic loading behavior of conventional and highly crosslinked UHMWPE. Biomaterials 2004;25(11):2171 - 2178.

4. Bergström JS. Computer modeling and simulation of UHMWPE. In: The UHMWPE Handbook, Kurtz SM (Ed.), Academic Press, New York, pp. 309-336, 2004.

5. Bergström JS, Rimnac CM, Kurtz SM. Molecular chain stretch is a multiaxial failure criterion for conventional and highly crosslinked UHMWPE. J Orthop Res 2005;23:267-375.

6. Bergström JS, Bowden A, Rimnac CM, Kurtz SM. Development and implementation of an advanced user material model for UHMWPE. Transactions of the 9th International LS-DYNA Users Conference, Dearborn, Michigan, July 4-6, 2006. http://www.uhmwpe.org/publications/pub_each.php?pubID=139

7. Bergström JS, Bowden AE, Oneida E, Sobieraj M, Wang A, Manley M, Rimnac CM, Kurtz SM. Validation of hybrid model and ultimate chain stretch criterion for a second-generation highly crosslinked UHMWPE. Transactions of the 6th Combined Meeting of the Orthopaedic Research Societies, Honolulu, Hawaii, Poster No. 498, October 21-24, 2007.