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 as Niemunis and Herle(1997) did. How can I make the value of q fluctuates within a certain range .When I make dsigma11-dsigma33=DX , and DX=[30,-60,60,-60,60,-60,60,-60,60,-60,60,-60] , the result is clearly not right. Any suggestions or comments will be appreciated. Thank you!
Question on the Matlab driver-hypoplastic models
Related Articles
-
Hardening Soil Model in Abaqus
Abulimiti Ayizula||Constitutive Modelling|4 |
Views 3,153
Is there Hardening Soil Model in Abaqus? -
Modelling TX monotonic compressive test with ABAQUS and SANISAND – not working
Riccardo Zabatta||Constitutive Modelling|8 |
Views 2,809
I am trying to reproduce a TX monotonic, compressive test on a sand by using a 1-element, axisymmetric ABAQUS FE model, assigned to a SANISAND material. For this purpose, I […] -
PM4Sand and PM4Silt models available
Katerina Ziotopoulou||Constitutive Modelling|3 |
Views 2,822
The constitutive models PM4Sand (Boulanger and Ziotopoulou 2017) and PM4Silt (Boulanger and Ziotopoulou 2018) for plane-strain earthquake engineering applications for sands, and clays and low-plasticity silts respectively are now available […] -
Interpreting results of sand hypoplastic model with Abaqus VUMAT
arsalan Ahmad||Constitutive Modelling|2 |
Views 2,735
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 […] -
Shear Stiffness Calculation for Hypoplastic Model
Hashmi Sohawon||Constitutive Modelling|4 |
Views 2,469
Hi David, I have reproduced some single elements test on ABAQUS using the UMAT to compare with Triax Hypoplasticity. So far, my stiffness curve (q vs ea) and my stress […] -
Initial Stiffness of CU test in Masin’s 2014 Model
Shen Wang||Constitutive Modelling|1 |
Views 2,387
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 […] -
PhD course “Hypoplasticity for Practical Applications”
Hashmi Sohawon||Constitutive Modelling|2 |
Views 2,730
Are the slides in regards to Stiffness Anisotropy for Clay Hypoplasticity for the PhD course available online? The available document {Mašín, D. (2015) Part 4: Determination of material parameters, PhD […] -
Non convergence problem in abaqus using hpoeca Clay Hypoplasticity in slope model
Yang Xue||Constitutive Modelling|4 |
Views 2,180
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 […]
Who is Online
No one is online right now
Search SoilModels Website
Recent posts
-
Zbraslav sand – Cyclic tests by Charles University 17.1.2023
-
New features in Excalibre 17.1.2023
-
Sanisand 13.1.2023
-
SaniSand Model in Plaxis 3D 9.12.2022
-
The GA-cal software for the automatic calibration of soil constitutive laws 2.12.2022
-
Abaqus OneAPI Compiler 10.11.2022
-
Few more Question on calculating lateral displacement of pile using hypoplastic clay model 3.10.2022
-
A question about the hypoplastic model in clay 22.9.2022
-
A High-Cycle Accumulation Model for Sand (Niemunis et al., 2005) 6.9.2022
-
Malaysian kaolin – Cyclic tests by Charles University 5.9.2022
-
Problem in calculating Lateral displacement of the pile using Hypoplastic clay model 2.9.2022
-
GTS NX 25.7.2022
Recent Comments
- Shruthija Sreeram on UMAT Implementation in Abaqus (Hypoplastic clay Subroutines)
- Paul Le Roux on Zbraslav sand – Cyclic tests by Charles University
- Amrane Moussa on Download package of a complete dataset “Zbraslav sand – Cyclic tests by Charles University”
- Francisco Mendez on The GA-cal software for the automatic calibration of soil constitutive laws
- Abolfazl Najafi on The GA-cal software for the automatic calibration of soil constitutive laws
- Arie Koot on SaniSand Model in Plaxis 3D
- Sajjad Shakeri on UDSM PLAXIS
- Anis Kheffache on Abaqus OneAPI Compiler
- Kassem Dib on How can I solve the error in Abaqus mentioned below?
- Dimitrios Konstantinidis on Issues in getting the negative values of q (mean deviatoric stress) while simulating cyclic triaxial test in ABAQUS using SANISAND subroutine.
- Tomáš Kadlíček on Download Package of Charles University Implementation of High Cycle Accumulation Model
- Safia EDAOUDI on Simulating Oedometer test in PLAXIS
- Safia EDAOUDI on Simulating the oedometric test with Abaqus
- MOHD SAQIB on Issues in getting the negative values of q (mean deviatoric stress) while simulating cyclic triaxial test in ABAQUS using SANISAND subroutine.
- Dimitrios Konstantinidis on Issues in getting the negative values of q (mean deviatoric stress) while simulating cyclic triaxial test in ABAQUS using SANISAND subroutine.
- Guilherme Castro on Download Package of Charles University Implementation of High Cycle Accumulation Model
- Giada Orlando on Download Package for Hypoplastic interface model and UMAT – FRIC interface
- Paul Le Roux on PM4Sand and PM4Silt models available
Hi C, the mixed control is not there predefined, but you can still add it easily into constraints.m file. Please study Janda, T. and Mašín, D. (2017). General method for simulating laboratory tests with constitutive models for geomechanics. International Journal for Numerical and Analytical Methods in Geomechanics 41, No. 2, 304-312 which is available in SoilModels publication database. You need to control axial stress
S(6,3)=1;
and radial strains so that zero volume strain is achieved
E(1,1)=1;
E(1,3)=0.5;
E(2,2)=1;
E(2,3)=0.5;
E(3,4)=1;
E(4,5)=1;
E(5,6)=1;
David
Hi, Prof.David. Thank you for your reply! As you mentioned, I change the constraint. However, there is still something wrong with it. I check the EE after I did what you mentioned, I found that the volume strain isn’t zero in the whole process. I was a little confused about these problems. I want to achieve the same result as Niemunis and Herle(1997) did. They controlled q fluctuates within a certain range. Is it possible for us achieve this through our matlab driver? Looking forward to your response!
Hmm, not sure why, this sets ep22=-ep33/2 and ep11=-ep33/2.
You may also try
E11=E12=E13=1, which sets ep11+ep22+ep33=0.
E21=1, E22=-1, which sets ep11=ep22
E34=E45=E56=1, which sets shear strain components to 0
S63=1, which sets axial (axis direction 3) stress control
This will, however, still not stop the test at predefined q, as radial stress will change during during loading through pore pressure generation. To achieve constant max and min q cyclic loading, you will have to manually set nstep for each load cycle, or add your own stop condition into the code, or better use some of more advanced element test software (such as triax or idriver).
Prof.David. in the f_hyp.m, after I make Laux = Lep and sigpresc = Laux*depsMNR-Nep*sqrt(depsMNR’*M2*depsMNR), the volume strain is zero, even though other results are not totally right in my views. While your file README.pdf clearly says that sigpresc = Laux*depsMNR rather than sigpresc = Laux*depsMNR-Nep*sqrt(depsMNR’*M2*depsMNR). I’d appreciate it if you could explain why sigpresc = Laux*depsMNR. Looking forward to your reply!
I see, I think the problem is how residual is calculated in Newton-Raphson iterations in Matlab driver. It is only calculated from residual stresses, which is insufficient for more complex mixed-controlled tests such as those we discuss here. Correct procedure is defined in Janda & Mašín (2017), where the residual is calculated from S*dsig+E*depsilon-dy, see Eq. (12).
For you, that would mean either updating Matlab driver formulation or using more advanced element test driver, such as triax