Dear all
I’m studying hypoplastic constitutive law from beginning concepts
I traced concepts successfully until i faced **rate independent topic**
i read this topic in the prof. Wolfgangs paper (hypoplasticity for beginners)
he said that “Rateindependence means that the gradient of the curve (stiffness) does not depend on the strain rate, Thus the stress rate must be precisely twice as large for a double strain rate” and in the fallowing he said that “the constitutive law may not have terms like (strain rate^2) (strain rate square )”
as you know the hypoplastic constitutive law is nonlinear in strain rate
my question is that how hypoplastic constitutive law can fulfill the nonlinearity (in strainrate) with no term like (strain rate^2)
Hypoplastic rate independent and nonlinearity
Related Articles

Cyclic constitutive model for cemented granular soils
Hamoun AlimoradiConstitutive Modelling2 Views 322
if you could please let me know whether Is there any constitutive model exist for capturing cyclic response for cemented materials just like cemented sand and gravelly soils. 
multi yield surface model
kamal paknejadConstitutive Modelling3 Views 388
Hi everyone, i am trying to write umat subroutine for multi yield surface plasticity model.if its possible give me some information to do my project better and if some body […] 
Sanisand model
sahar saabConstitutive Modelling1 Views 264
Is the Sanisand constitutive model 3 dimensional? Could it be used for dry sand cases using C4D8 elements? (drained sand) Is it possible to apply it in a dynamic implicit […] 
Subroutine of SANISAND model
Pooja PatilConstitutive Modelling13 Views 780
I am trying use sanisand subroutine posted in this website. But it is not working. Getting no values for field variable in the odb. I think i am missing something. […] 
Undrained Tests with Clay Hypoplasticity Intergranular
Hashmi SohawonConstitutive Modelling1 Views 365
Hi all, I wanted to share these results to show that the use of the hypo clay model does in fact give more realistic undrained stress paths for clays on […] 
CEL analysis using hypo plasticity Vumat
abd ElfattahConstitutive Modelling8 Views 698
Greetings i used interface Vumat with Umat for simulating CEL problem, after 50% of analysis, i got the error as “Excessive incremental rotation of the elements in element set ” […] 
New book “Modelling of Soil Behaviour of Hypoplasticity”
David MašínConstitutive Modelling0 Views 579
I have just returned to Springer proofs of my new book “Modelling of Soil Behaviour of Hypoplasticity – Another Approach to Soil Constitutive Modelling“. It will probably still take few […] 
Problems with the UMAT subroutine check_parms_DM of the SANISAND constitutive model
meng xiaoweiConstitutive Modelling3 Views 364
Where can I find the source of the content in the picture below in the UMAT subroutine check_parms_DM of the SANISAND constitutive model?
Search SoilModels Website
Recent posts
 ERROR Message when using UMAT_hcea with ABAQUS 3.7.2020
 Slope stability calculation with hypoplasticity using phic reduction available now in download section 30.6.2020
 SANICLAYB (2018) how to calculate Dep 22.6.2020
 ABAQUS modeling: Warning about unconnected regions when using hypoplasticity subroutine 16.6.2020
 Calibration of the von Wolffersdorff model using Genetic Algorithms 16.6.2020
Recent Comments
 Fernando Guzman on Download package of a complete dataset “Karlsruhe fine sand – Cyclic tests (T. Wichtmann)”
 Francisco Mendez on Calibration of the von Wolffersdorff model using Genetic Algorithms
 Wang Shun on Calibration of the von Wolffersdorff model using Genetic Algorithms
 Jasmine Lokesh on Hypoplastcity sand model
 Jasmine Lokesh on Hypoplastcity sand model
 David Mašín on Hypoplastcity sand model
 Jasmine Lokesh on Hypoplastcity sand model
 Jasmine Lokesh on UMAT Implementation of Sand Hypoplasticity by UIBK
 Wolfgang Fellin on UMAT Implementation of Sand Hypoplasticity by UIBK
 Wolfgang Fellin on UMAT Implementation of Sand Hypoplasticity by UIBK
 Jasmine Lokesh on UMAT Implementation of Sand Hypoplasticity by UIBK
 Jasmine Lokesh on UMAT Implementation of Sand Hypoplasticity by UIBK
Dear Sobhan, hypo equation is defined as stressrate=L:strainrate * Nstrainrate. Here, strainrate is Euclidean norm of strainrate, that is sqrt(strainrate:strainrate). You see that the equation is nonlinear in strainrate (if strainrate changes direction, stressrate changes direction differently as the term with N only quantifies strainrate size, not direction). You also see that actually, units of strainrate are still 1/time, as there is sqrt(strainrate^2) involved, thus it is consistent with comment by prof. Wolffersdorff which you cited. I suggest to have a loom into my book “Modelling of Soil Behaviour with Hypoplasticity”, where fundamentals of hypoplasticity are explained in (hopefully) clear way. Regards David
thank you so much!