| Application | PLAXIS 2D PLAXIS 3D |
| Version | PLAXIS 2D PLAXIS 3D |
| Date created | 01 October 2012 |
| Date modified | 25 October 2023 |
PLAXIS has a facility for user-defined (UD) soil models. This facility allows users to implement a wide range of constitutive soil models (stress-strain-time relationship) in PLAXIS. Such models must be programmed in FORTRAN or another programming language, and then compiled as a Dynamic Link Library (DLL). Finally, you need to add this DLL to the PLAXIS program directory.
In principle, the user provides information about the current stresses and state variables and PLAXIS provides information about the previous ones and also the strain and time increments. In the material database of the PLAXIS input program, the required model parameters can be entered into the material data sets.
For more details, please read the attached document and example code.
These user-defined soil model's DLL files should be placed in a subfolder called udsm. Below you can find the default locations for the PLAXIS application.
Example for PLAXIS 2023.2:
Note: replace "2023.2" with "2023.1" when using that PLAXIS 2023.1.
Example for PLAXIS CONNECT Edition Version 22:
Note: replace "V21" with "V21" or with "V20" when using that PLAXIS CONNECT Edition V21 or V20.
PLAXIS Legacy versions (PLAXIS 2D AE - PLAXIS 2D 2019, PLAXIS 3D 2013 - PLAXIS 3D 2018), these user-defined soil model's DLL files should be placed in a subfolder called udsm:
All dongle/hardware lock (HWL) based versions of PLAXIS 2D/3D are treated as "V8i SELECTseries 10" according to Bentley's Support Policy. This means that Bentley will discontinue support for hardware lock-based versions of PLAXIS after December 31, 2021. This includes PLAXIS 2D 2019 and older, and PLAXIS 3D 2018 and older.
To see the benefits of the latest versions and how to get the latest version, please see PLAXIS CONNECT Edition: upgrade from Hardware lock to Flexible licensing
For older versions (PLAXIS 2D 2012, PLAXIS 2D Classic and earlier and PLAXIS 3D 2012 and earlier) the user-defined soil model's DLL files should be placed in the program's installation folder, e.g.:
Disclaimer: the Bentley Systems, Inc and PLAXIS organisation cannot be held responsible for any malfunctioning or wrong results due to the implementation and/or use of user-defined soil models.