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  1. Lemine

    How to implement an integral over a volume expression in a user subroutine Umat

    Hello FEA Engineers, Any idea about this topic Thanks in advance for your help !
  2. Lemine

    How to implement an integral over a volume expression in a user subroutine Umat

    Thanks a lot, Dear IceBreakerSours for your response, Yes absolutely the result is a scalar and I want to sum up the expression over the volume, Matrix 1 and Matrix 2 are expressions of stress tensor so after processing I know their values in the structures,and the 4th order tensor is also...
  3. Lemine

    How to implement an integral over a volume expression in a user subroutine Umat

    Hello, I want to implement the expression below in Abaqus analysis using the Umat subroutine. Matrix1 and Matrix2 are seconde order tensor A is a forth order tensor The : represent the contracted product Omega is the geometry How this can be implemented Thanks in advance for your response
  4. Lemine

    Asign Initial Solution-dependent State Variable to a particular group of elements ?

    Thanks a lot Dear FEA way, Yes I tried to use the NOEL information, but I have difficulty in Fortran code: Can you please help how to define these two-line in Fortran code? element1,component1,component_2,component_3,component_4 element2,component1,component_2,component_3,component_4 ... Or how...
  5. Lemine

    Asign Initial Solution-dependent State Variable to a particular group of elements ?

    Hello, I have a problem assigning Initial Solution-dependent State Variable to a particular group of elements In Umat. By adding lines in the *inp file: *Initial Conditions, Type=Solution,User [Elemet_set], Value(1)..., ..... and, from Abaqus documentation I see that the SDVINI subroutine can...
  6. Lemine

    How to calculate residual stress from plastic strain tensor in abaqus?

    Thanks to all for your response, Thanks, Mustaine for your suggestion, I try to create the initial static step in Abaqus, in this step, I just define the initial plastic strain and I didn't apply any load, and the result is still the same at the end of the step "Stress always zero", can you...
  7. Lemine

    How to calculate residual stress from plastic strain tensor in abaqus?

    Thanks for your response, yes it's verified and tested, but the problem above remains. Thanks for your help
  8. Lemine

    How to calculate residual stress from plastic strain tensor in abaqus?

    Thanks for your response, Yes I use the keyword *Initial conditions, type=plastic strain, to define the initial plastic strain but my question is that regardless of the value of the initial plastic strain applied the initial stress is shown always zero in Abaqus and this is not right? so how to...
  9. Lemine

    How to calculate residual stress from plastic strain tensor in abaqus?

    Doing a cyclic calculus in Abaqus and at the beginning of each cycle I apply an initial plastic strain, we know that when we apply initial plastic that implies the presence of stress resulting from the plastic deformation, but Abaqus always show initial stress null at the beginning of the cycle...
  10. Lemine

    How to compute initial stress if we applied initial plastic strain in Abaqus ?

    Hello, I have applied initial plastic strain in Abaqus using *Initial Conditions, type=Plastic strain and I want to use the corresponding initial stress value but Abaqus always initialize stress as zero despite the value of initial plastic? Can you help to overcome this problem, please? Thanks...
  11. Lemine

    Iterative calculation in Abaqus by updating the plastic strain components ?

    Thanks a lot, If the .inp file can read information from the appropriate file at each iteration, That exactly what I would achieve. If you have a link to an example would be very helpful. Thanks a lot again
  12. Lemine

    Iterative calculation in Abaqus by updating the plastic strain components ?

    Thanks a lot, Dear FEA WAY, for your response, I know how to extract all the plastic components from the .odb file, but the problem is how to update them in *Initial conditions (in the .inp file) at each iteration? Thanks again,
  13. Lemine

    Iterative calculation in Abaqus by updating the plastic strain components ?

    ...in the previous analysis (extracted from .odb files). I Know how to initialize plastic strain components in the .inp file using the keyword : *Initial Conditions, type=PLASTIC STRAIN, for a simple analysis but I want to automate the process using python scripting. Any ideas or help are highly...
  14. Lemine

    How to compute residual stress in Abaqus CAE?

    Thanks a lot I perform a cyclic loading and at the end of the step the load equal to zero so the result would be the same as we create a new step? Thanks again
  15. Lemine

    How to compute residual stress in Abaqus CAE?

    Thanks for your response, For example, I have a structure "elastoplastic" and I applied some loads and I submit the job in the post-processing at the end of the step (the load is zero) so what Abaqus Visualize is the residual stress or the total stress? Thanks
  16. Lemine

    How to compute residual stress in Abaqus CAE?

    Hello, engineers, Is there a way to calculate the residual stress in Abaqus? thank you for your help
  17. Lemine

    VISCOPLASTIC LAW - Norton Hoff - ABAQUS ?

    Thanks a lot dear Mustaine for your reply. Is it possible to determine the parameters of two-layer viscoplasticity model in Abaqus (A,n,m,f) from the expression of dissipation potential ? If the umat is the only solution I would be so thankfull if you can share a Umat exemple near to my case...
  18. Lemine

    VISCOPLASTIC LAW - Norton Hoff - ABAQUS ?

    Hello Engineer's, I'm having trouble to set the dissipation potentiel of Norton Hoff below (cf.Image) to model the viscoplastic reponse of structure in Abaqus. I want to know if programming UMAT It is the only way to overcome this problem? Thanks in advence for your help Regards,
  19. Lemine

    How to minimize cost function define over volume omega using BFGS algorithm?

    Hello Mechanical engineers, I have computed a cost function J(x1,..xn) and her gradient J'(x1,..xn) defined over a volume using finite element analysis. so I have the value of these fields J and J' at n nodes (x1,..xn) in the geometry (integration point) and I have saved the data in a text...
  20. Lemine

    How to minimize cost function define over volume omega using BFGS algorithm?

    Hello, Engineer and Mathematician programmer, I have computed a cost function J(x1,..xn) and her gradient J'(x1,..xn) defined over a volume using finite element analysis. so I have the value of these fields J and J' at n nodes (x1,..xn) in the geometry (integration point) and I have saved the...

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