Dear All,
I am using sand hypoplastic model in my research and I have encountered some problem when looking into cyclic simple shear test in the range of small strains.
Firstly, I have tried to simulate cyclic simple shear test from Shahnazari & Towhata (2002), Fig. 5, on Toyoura Sand. It is in the range of medium strains, up to 3%. The simulation looks really good (see attached pdf file). The sample contracts systematically with cycles thus the stiffness increases as per the experiment. Note contraction is with negative sign, Abaqus standard notation.
Secondly, I have subjected the same sample to cyclic loading but with significantly reduced strain amplitude, i.e. 0.1%. As expected, also here the sample contracts, however, the stiffness decreases with cycles which to me does not seem physical.
The model is calibrated as shown in Herle & Gudehus (1999) Table VII for Toyoura Sand. Intergranular strain parameters are set to also rather common values: R=0.0001, m_R=5.0, m_T=2.0, Beta=0.5, ksi=6.0. I have tried using both umats, from prof. Masin and prof. Fellin, both give the same answers.
I am wondering where is it I can be wrong here. Theoretically, I think I should be able to model sand behaviour for both strain levels with a single set of calibrated parameters.
Thank you all in advance for any comments and tips on how to approach my problem.
Regards
Cyclic simple shear test simulation with hypoplasticity
Related Articles

Modelling TX monotonic compressive test with ABAQUS and SANISAND – not working
Riccardo ZabattaConstitutive Modelling9 Views 4,234
I am trying to reproduce a TX monotonic, compressive test on a sand by using a 1element, axisymmetric ABAQUS FE model, assigned to a SANISAND material. For this purpose, I […] 
MATLAB Code for Bounding Surface Plasticity Model
A S M RIYADConstitutive Modelling0 Views 3,963
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 […] 
Spurious oscillations in calculated accelerations
Piotr KowalczykConstitutive Modelling2 Views 3,876
Hello everyone, I have just a general question how people approach the problem of spurious oscillations generated in dynamic analysis when using nonlinear soil constitutive models. I understand sometimes numerical […] 
Htypoplastic Model in Miidas GTS NX
Kassem DibConstitutive Modelling6 Views 1,967
Hello.. I am defining the hypoplastic parameters for Karlsruhe sand (found in a paper) using MIDAS GTS NX. In the software the a requesting (in addition of parameters) the number […] 
ExCalibre Automatic Calibration
Marco HoferConstitutive Modelling2 Views 3,880
Hello all, i hava a problem with the Oedometer curves after the automatic calibration with ExCalibre. I took the Dobrany sand dataset for an automatic calibration and then i copied […] 

Question on the Matlab driver – model hypo Sand
c sxConstitutive Modelling1 Views 3,710
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. […] 
Question on the Matlab driverhypoplastic models
c sxConstitutive Modelling5 Views 3,705
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 […]
Who is Online
No one is online right now
Search SoilModels Website
Recent posts
 Hardening soil Model UMAT 13.9.2023
 Problem with VUMAT interface 20.8.2023
 UMAT and oneAPI compiler issues. (SOLVED…i hope :p) 5.8.2023
 Oedometric Test Soil Test Plaxis 21.7.2023
 Problem in simulating CPT using SANISAND04 10.7.2023
 Problem with UMAT for clay hypoplasticity. Program exiting. 30.6.2023
 Example of FLAC3D data file 10.6.2023
 sigini ans sdvini subroutine example for soil model in Abaqus 6.6.2023
 Presentations from Prague Geotechnical Days 2023 including 29th Prague Geotechical Lecture by Yannis Dafalias 25.5.2023
 Problem in using Hypoplastic model for sand in Abaqus. 17.5.2023
 An error in the SANISAND umat runtime 8.5.2023
 Htypoplastic Model in Miidas GTS NX 25.4.2023
Recent Comments
 Shuo Feng on Download Package of Matlab Driver
 Ajay Jatoliya on SANISAND for FLAC3D Download
 Isma Khabis on Hardening soil Model UMAT
 Anis Kheffache on Hardening soil Model UMAT
 Isma Khabis on Hardening Soil Model in Abaqus
 Fatemeh Safari on Matlab Driver
 KF JIAO on SANISAND Abaqus UMAT and Plaxis implementations
 Abdiel Ramon Leon Bal on Problem in simulating CPT using SANISAND04
 An Zhanng on Problem in simulating CPT using SANISAND04
 Giovanni Ciardi on UMAT and oneAPI compiler issues. (SOLVED…i hope :p)
 Anis Kheffache on UMAT and oneAPI compiler issues. (SOLVED…i hope :p)
 Giovanni Ciardi on UMAT and oneAPI compiler issues. (SOLVED…i hope :p)
 Anis Kheffache on UMAT and oneAPI compiler issues. (SOLVED…i hope :p)
 Giovanni Ciardi on UMAT and oneAPI compiler issues. (SOLVED…i hope :p)
 Anis Kheffache on UMAT and oneAPI compiler issues. (SOLVED…i hope :p)
 Giada Orlando on Problem in using Hypoplastic model for sand in Abaqus.
 Giada Orlando on UMAT and oneAPI compiler issues. (SOLVED…i hope :p)
 Giada Orlando on Problem in using Hypoplastic model for sand in Abaqus.
Dear Piotr,
The simulation in the range of medium strains looks really good and the parameters are typical, so I consider that the simulations are well performed. However, the behavior under small strains is unrealistic. In my opinion, this is a model limitation. Some authors have demonstrate the difficulty of reproducing different kinds of test conditions with a single set of parameters (which is a wellknown drawback of the models, and is discussed in some works e.g. [1])
Regards,
Jose Duque
[1] Wichtmann, T. (2016), “Soil behaviour under cyclic loading: Experimental observations, constitutive
description and applications”, Habilitation, karlsruhe institute of technology (KIT).
Hey Jose
Thanks for the reply. It also seems to me to be a case as you described.
Actually, using more recent calibration from prof. Herle, with quite different set of the model parameters, seems to improve a bit the problem, not completely though.
Regards