The visco-elastic perfectly plastic model is a simple and robust model that can be used to model time-dependent behaviour (creep and relaxation) of various materials. It is available as a user-defined soil model Dynamic Link Library (DLL). This DLL can be obtained from and is supported by Plaxis. However, Plaxis does not accept any responsibility when using this DLL. Hence, the user needs to validate results obtained from this model by him/herself.
With the release of PLAXIS 2D/3D CONNECT Edition V20 Update 1 (January 2020), the PLAXIS User Defined Soil models are delivered with the PLAXIS installation. When enabling the Geotechnical SELECT Entitlement [GSE] when starting the PLAXIS application, this model becomes available in the Parameters tab when selecting "User defined" for the Material model.
How to use a user defined soil model in PLAXIS
Plaxis User Defined Soil Models
64 bit User Defined Soil model
[Tips and Tricks]