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  1. WayneKagawa

    Best strategy for verification of tangent for hyperelastic material

    Let's say I have a strain energy density function W = W(I1,I2) + W(I3). The second PK stress is then defined as S_{ij} = ∂W/∂E_{ij} and the constitutive tensor C_{ijkl} = ∂/∂E_{kl}(∂W/∂E_{ij}). If I want to verify that I'm deriving the correct analytical constitutive and stress tensor...
  2. WayneKagawa

    Normal and Tangential Contact problem

    I am trying to model the slip and separation between a Nuclear reactor and soil when hit by a bi-directional earthquake using the interaction feature. The interaction that I am trying to model is as follows: Normal - Stiffness acts only when the surfaces are in compression and there is no...
  3. WayneKagawa

    Interaction model for separation of edges in 2D

    The problem is that the penetration and separation of surfaces is higher than I expected. I used a pressure-overclosure definition with linear stiffness. Also the EQ time histories have been applied at both the sides and the base.
  4. WayneKagawa

    Interaction model for separation of edges in 2D

    Hi all I am modeling the slip and separation of a structure resting on soil in 2D when affected by both transverse and vertical TH of an EQ. I am using interaction properties as mentioned below: Tangential: Penalty -> Coeff of Friction, Shear Stress limit, maximum elastic slip Normal: Linear ->...
  5. WayneKagawa

    problems with displacement during friction

    Hi The intent was to check the load where it slips and to reduce computational time. Hence I gave a large increment. The behavior was as expected. I'm just a little curious as to why it has to slip even by that little amount before the critical load. I'll work on your suggestion of using a...
  6. WayneKagawa

    problems with displacement during friction

    Hi Thank you Mustaine3 and Cooken. I had a look through the manual and read the part regarding penalty method, lagrange method and elastic slip quite thoroughly. I inferred from the text as well as from Cooken's observation that Abaqus assumes a certain elastic slip during the penalty method...
  7. WayneKagawa

    problems with displacement during friction

    To test out friction in ABAQUS, I tried to model the interaction between two blocks in 3D, the smaller one(1x1x5)resting on the Larger one (10x10x10) with both having a mass density of 1000 kg/m3. The interaction was defined as follows: Tangential Behaviour - 0.7 (friction coefficient using the...
  8. WayneKagawa

    Choosing a contact element on Abaqus

    Hey I am no expert but I am kind of working on a similar problem in 2D. I am using a cohesive surface to surface interaction that considers normal and tangential stiffness that come into play only in compression using the master and slave surface phenomenon.I read about them in the Abaqus...
  9. WayneKagawa

    Incorrect Reaction for Unit Displacement

    Hi guys I tried iterating the mesh size. I found that as I increase the global mesh seed, the reaction force increases. I suppose this follows from the logic that a larger mesh size makes for a stiffer surface whereas a lower mesh size makes the surface more flexible. Even though now I am...
  10. WayneKagawa

    Incorrect Reaction for Unit Displacement

    Hi Bkal I haven't tried shell elements as the paper mentions the use of solid elements for the analysis. I used the tet mesh with a "free" orientation and reduced the mesh size a little more to about 0.9 which did result in a higher reaction than before but still about 25% less than what it...
  11. WayneKagawa

    Incorrect Reaction for Unit Displacement

    Hi bkal I appreciate your effort to help me and I apologize for unsatisfactory information. I am new to this forum and I will improve upon this. By shell, I meant to describe that I am only considering the outer concrete surface and not the internal components of the containment structure. I...
  12. WayneKagawa

    Incorrect Reaction for Unit Displacement

    The paper just gives the number of meshed elements in the model which I iterated the mesh size to find out. The element type as such is not mentioned so I used the default solid mesh element with hybrid formulation. Also, the paper mentions the young's modulus and the shear modulus which are...
  13. WayneKagawa

    Incorrect Reaction for Unit Displacement

    Hi I am modelling a lumped mass model of the outer shell of a Nuclear Containment Structure given in a research paper.It is a hollow cylinder with a dome placed on top. To find out the total lateral stiffness, I applied a Unit displacement at the topmost node of the structure and checked the...
  14. WayneKagawa

    Problem with reaction forces in ABAQUS.

    Hey I would suggest the history output feature. In its domain field, hover down to Set and select the set whose resultant you want to see. Assign the type of results you want for that node. After the Analysis is over, head to Result -> Field History Output. In here, select the type of result...

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