Hello All, I am getting started with implementing UMAT for soil model in ABAQUS. I am planning to use Hypoplastic clay constitutive soil model to simulate the triaxial tests. I […]
Dear all, Thanks for hypoplasticity sand UMAT provided by Prof. Masin. During studying hypo sand UMAT, I am encountered with a question about consistent tangent stiffness calculation. subroutine ”perturbate_h“ seems […]
Dear forumers: Thanks to hypoplasticity sand UMAT provided by Prof. Masin — https://soilmodels.com/download/plaxis-umat-hypoplas-zip/. But during studying above sand UMAT, I found that the stress order may be incorrect. Because stress […]
ALERT doctoral school on constitutive modelling – hands on session triax input files
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ALERT doctoral school on constitutive modelling is happening right now. The school lecture notes are available at the website of ALERT geomaterials (http://alertgeomaterials.eu/publications/) Below you find triax input files for […]
Hi, I am using Hypoplasticity model with explicit asymptotic boundary surface proposed by Prof. Masin in 2014. In this model, parameter ‘nu’ controls initial stiffness in CU test. But when […]
Can SANISAND version given in soil model work well for cyclic simple shear test ?
Hi Admin, I have been using hypoplastic subroutine supplied by this website. It works well in ABQ6.14 and ABQ2017. However, recently I have to upgrade to ABQ2021 due to an […]
Dear Altruists, I just wanted to learn the bounding surface plasticity theory with coding. Does anyone have any code (written in MATLAB) for the Bounding Surface Plasticity model? Could you […]
Non convergence problem in abaqus using hpoeca Clay Hypoplasticity in slope model
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hello everyone! based on the strength reduction method in clay hypoplasticity, firstly, I used two steps belong to the static_general, the first step is impose a gravity load, and not […]
Anyone has any reference to writing UMAT file for Poro linear elastic properties or what constitutive equations have to be solved to do the same. Any help would be appreciated […]
Hi everyone, i am trying to simulate DSS/cDSS test in drained/undrained conditions and I was wondering how the constraints matrices should be ? while it is easy to understand how […]
Hello, I was trying to simulate the unloading process of clay consolidation in Abaqus using clay hypoplasticity umat (https://soilmodels.com/download/plaxis-umat-hypoplas-zip/). But I had a convergence issue showing in Fig.1. The model […]
Hello, I was trying to simulate the unloading process of clay consolidation in Abaqus using clay hypoplasticity umat (https://soilmodels.com/download/plaxis-umat-hypoplas-zip/). But I had a convergence issue showing in Fig.1. The model […]
PLAXIS 2D require a “Lateral Resistance ” for the embedded pile row. The manuals are not very clear as to what the resistance represents? Is it on friction ( similar […]
Dear All, I am using ISA+HP model in my research and I have encountered some problem when looking into cyclic triaxial test for single element. The target model was selected […]
Hi everyone. When i try to run the matlab driver I get the following error, how can i sove it ? (The constructor for class ‘update’ must return only one […]
Dear all, I have a question about Hypoplasticity for sand model, i am having trouble to understand about how to calibrate the mr parameter ? Since no formula is provided […]
Hello Everyone, I am using the UMAT code for clay hypoplasticity provided by Prof. Masin — https://soilmodels.com/download/plaxis-umat-hypoplas-zip/ I made a oedometeric test model in Abaqus2018 and applied the umat code […]
I implemented a unified dynamic soil model, but PLAXIS doesn’t calculate any strains, and it prints zero (or some times NaN amounts) into a text file. I’d like to know […]
I am using SANISAND to simulate a triaxial compression test under monotonic loading. But every time my simulations break and give the same message “Abaqus/Implicit Packager exited with an error […]
Hi! I am studying the behavior of kaolin clay under cyclic loading. The strain rate is kept at such that undrained behavior is maintained. I want to use an advanced […]
Hi Prof. Masin , It is related to my previous post. Sorry to bother you again. I simulated Oedometer test in Plaxis as well as centrifuge reloading (using HP clay […]
Soft soil and soft soil creep model both include time while performing the analysis. What is the difference between both of them.
Using PLAXIS, how to model rate dependent behavior of clay. This is to show the viscous behavior of the soil. Thank you in advance
I have the license, but can’t login as it is a server license. In order to access this model, i need the .dll file. Can anyone help me with this. […]
Is there Hardening Soil Model in Abaqus?
Dear All, I am currently using the hypoplastic model for gran materials from Prof. von Wolffersdorff to simulate soil excavations in a context of large deformations. I have been searching […]
Hello all, I am trying to implement boundary surface plasticity using Bardets model in MATLAB. But i am obtaining negative values for q and Dep. Any help in this regard […]
Hello Everyone, Can anyone have umat available for SANISAND 08 (Simple anisotropic sand plasticity model)?. Paper authored by Taiebat and Dafalias. They have used a closed type yield surface. Regards […]
Issues in getting the negative values of q (mean deviatoric stress) while simulating cyclic triaxial test in ABAQUS using SANISAND subroutine.
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Hello Everyone, I have been trying to simulate the cyclic triaxial test using the SANISAND04 subroutine. When I plotting the stress path (p-q plot), I am getting only the positive […]
Dear all, I am pretty new in coding and using Abaqus. I have trouble with coding the UMAT for NorSand. If any of you have any good references, please share […]
Dear concern, Recently i have modelled the soil pile interaction using Abaqus CEL method. The hypoplastic behavior of the soil is model using user subroutine VUMAT. The properties of the […]
Hi everyone: I am trying to use SANISAND as the constitutive model of soil, and use ABAQUS software to simulate pile-soil interaction. First step is “Geostatic”, the second step is […]
Dear all, After carefully reading the matlab drivers of hypoplastic models, I was wondering whether the driver can simulate triaxial extension tests. As I change the constraints to reflect triaxial […]
I am trying to develop UMAT code for MCC, but facing difficulty. Is there any such files available which can help me to speed up. please refer. Thank you.
Dear all, does anyone have the umat code for Mohr Coulomb in Abaqus? For my current work I need a umat for Mohr Coulomb in Abaqus. It would be highly […]
Hi everyone: I am trying to use SANISAND as the constitutive model of soil, and use ABAQUS software to simulate pile-soil interaction. Is it better to choose “Static, Genaral” analysis […]
Hi, I am going to use the usdfld to function the density of sand changing due to confining pressure. I am not sure Abaqus will call the usdfld for every […]
Hi to everyone I want to model a Sand with Cap plasticity or Drucker Prager failure criterion in ABAQUS, and I have the result of Triaxial test (I’ve attached the […]
Dear all, Recently, I have been working on the simulation of a pile-soil interaction with CEL method in Abaqus/Explicit. I simulate the sand with the Sand Hypoplasticity Model provided by […]
Dear all, After carefully reading the matlab drivers of hypoplastic models, I was wondering why there is not mix control undrained TX compression. I want to achieve the same result […]
Hypoplastic Interface Model: Does anybody implemented this model in FLAC3D
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I want to use this model to simulate soil-structure interaction in FLAC3D software, so I was wondering does anybody implemented this model in FLAC3D, and could you please share your […]
Dear all, I am a PhD student in China University of geosciences. Recently, I have been working on the simulation of a pile-soil interaction with Abaqus. I simulate the sand […]
General questions on implementation of sand hypoplasticity model with Abaqus umat
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Dear all, I am a PhD student in Zhejiang University. Recently, I have been working on the simulation of a braced excavation with Abaqus. I want to simulate the soil […]
As a beginner to soil constitutive modelling, I am learning the hypoplastic models by reading the matlab drivers. I am confused with the matlab file f_hyp.m in the model hypo_sand. […]
Dear all, I am currently writing a proposal for a (small & hopefully nice) eLearning project: Within the project, I would like to create animations related to constitutive modelling. I […]
Hi all! I am modelling some triaxial compressions in ABAQUS with Weald Clay. The constitutive law i am using is the clay hypoplasticity by Mašín. When running the program using […]
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Recent posts
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Postdoctoral position at COFS, UWA 28.7.2025
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Hypoplasticity clay in ABAQUS 23.7.2025
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Drucker-Prager Cap 29.5.2025
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Abaqus RITSS with hypoplastic 9.4.2025
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Fellin UMAT subroutine 2.4.2025
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Hypoplasticity clay for triaxial compression in abaqus 26.3.2025
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Abaqus RITSS methon for LDFE analysis with hypoplastic 17.3.2025
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Request for VUMAT Implementation of Mohr-Coulomb, Drucker-Prager, or Drucker-Prager Cap 28.2.2025
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Suggestions for an Advanced Constitutive Model in FEM-Based Dynamic Slope Stability Analysis 12.2.2025
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Hardening Soil or Hardening Soil-Small umat in Abaqus 2.1.2025
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hypoplastic interface 11.12.2024
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Triaxial Test Driver SANISAND 30.10.2024
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