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About Amar17

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  1. Hello Everybody, We keep eye on element quality criteria in order to get a good quality mesh. Anybody would please tell me in what way does every element criteria (such as Warpage, Aspect ratio, Jacobian, skew etc) affect the results? I know that ideal element shapes are square and equilateral triangle (for 2D elements) and any diversion from the ideal shape would lead to negative effect on the results. But what effect does every criterion has on the result?
  2. Hello Everybody, How does it affect the results when we do not specify the damping ratio? How may I know what is the default value of damping ratio my solver is taking? Does it affect the maximum stress induced in the body? Please put some light on it.
  3. Hello Everybody, To verify the results and to check the mesh quality, one method we use is to refine the mesh and check the results. To increase the mesh density, isn't it that we have to re-mesh the model again ? Particularly for the case of analysis of large assemblies, the task may become a cumbersome one. And for the case of explicit analysis it becomes worse since we also need to take care of the time step. Then how is it possible to refine the mesh with least possible efforts? Please guide.
  4. Thank you sir! The minimum length in my case here is 1.5 mm and with that I am getting the aforementioned aspect ratios. Since I am solving the problem in Radioss, with a transient load, I also need to take care of the time step. Apart from the element type used is my mesh still okay?
  5. Hello Everybody, I am trying to bring a good quality hexa mesh. The mesh I am getting is good in almost all the quality criteria except 'aspect ratio'. I am getting the aspect ratio values in range 3 to 5. I have read that the acceptable aspect ratio is below 5, so my mesh should work. But what I am expecting is to get a good quality mesh in the area since it may be the region of high stress. My question is how good my mesh is if it is to rate between 1 to 10? (I am getting a very good mesh for rest of the quality criteria) And to what extent my results may get affected if I fail to bring a proper mesh in the region? The attached illustrative image may be referred. The 3D mesh will be connected to 2D mesh and the the analysis is explicit (Radioss). Please advise.
  6. Hello everybody, Many times when solver takes a long run time to solve given analysis problem, it becomes a big concern when we loose electricity connection in between. How to continue the analysis when the power resumes?
  7. Hello everybody, my question is, what yields more stress static or dynamic (transient) analysis? According to what I could know up til now, it is dynamic analysis in which the stress values are expected to be higher in case of the static analysis. It it always likely to happen that stress values will be higher in case of the transient analysis if I perform both analyses for the same structure? Please guide.
  8. Sir, I tried checking time step with Check elements Panel, but an error popped up:- "HM_CALC_TIMESTEP_func: Division by zero error" Does the F10 panel calculates considering both the elemental and nodal time steps? Also, What care we should take to keep the nodal time step maximum?
  9. Hello everybody, I want to perform an explicit analysis in radioss. I have read that we follow a time step of 1E-06 sec for steel with minimum element size of 5 mm. In my case the element size goes up to 1 mm. I have gone through the book "Crash Analysis with Radioss", according to which we have to look for two formulae to calculate the time step- one is elemental time step and the other is nodal time step. With an approximate sound speed of 5000 m/s through steel, I calculated the time step of 2E-07 sec [i.e., 1 mm / 5000 m per sec]. But I am not able to figure out how to calculate the nodal time step? Would somebody help me out with this? My question is - how much smaller time step would I require to take (for steel) in this case? [Please suggest me an optimum- rough estimate for the element size of 1 mm for steel by taking into consideration the nodal time step also].
  10. Thank you for that sir! But what about connection between the two bodies? Should we merge the nodes at the connection or provide some connection? For the latter case what type of connection you would suggest me for an explicit analysis (in Radioss)?
  11. I have a 2D to 3D connection as shown in the attached image. Please guide me for this.
  12. This means we can store different element types of a single solid in different component collectors and assign them different formulations. Wouldn't it create any problem? Because, once when I was analyzing an assembly, I stored all the component in a single collector and wasn't able to find any penetration. Please tell me if I need to take care of any such probable concern while defining element formulation for different element types in a single solid?
  13. I have a component meshed with different elements (Hexa, Penta and tetra). The problem I am facing is while defining the element formulation of the component. How one can define element formulation in such case? The problem is the same for the case of 2D plates when we encounter quad and tri elements in a component. I also searched the answer for this in the book "Practical aspects of FEA" but couldn't find it. Please guide me through the problem.
  14. Hello Everybody, I am trying to mesh a stepped cylinder. In HyperMesh we find the surfaces of cylinder get divided into to halves. In my case, as these halves are connected, I am not able to get an uniform 2D mesh at the cross section. I have tried to toggle the partition lines but couldn't solve the issue. Please tell me, how may I get this resolved. I am attaching the images of my problem
  15. Thank you Nguyen-Dai! But after doing this way, the elements on the new surface are not connected to the elements from previous surface.
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