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Everything posted by Mrt

  1. did you solve eigenfrequency? in frequency/modal analysis displacement/stress doesn't matter. could your explain what did you do? and show, please, your result pics.
  2. optistruct reference guide=) opti control->
  3. could you show result pics and load pics? you have more grids in your model now and it can change your loading.
  4. @LOKESH KATARI DOFs are depended on element numbers/types. quad shell first order has 4 points and 6 dofs on every point=24 DOFs. If you create full vehicle model which contains 100.000 points (only shell elements and beams) you will have 6*100.000 DOFs if you separete chassis from full model and it will include only 50.000 points you can estimate your reduction coefficient=)
  5. try "-nt 2" or delete options -both and check "use SMP:-nt 2"
  6. at first-Do you use HyperMesh? or LSprepost? your surface: just mesh it!=) like this, Anna! p.s. i don't know why, but in this area your mesh shoulbe like in my pic below... otherwise HM won't make solid mesh right. if your solver will be dyna you should know about timestep.=)
  7. your mesh is good, guy! don't worry=) just unchek "min size"
  8. if i were you i would make mesh by the way as shown below.
  9. Вам следует мельче побить Вашу сетку. и если Вы хотите вывести эл-ты с плотностью (допустим 0,3) вы ничего хорошего не получите, Катерина. у Вас есть мануал по отистракту и файлы к нему? you should do refine mesh. if you want to see elements with density (exmpl 0.3) you couldn't see anything determined, Kate. Do you have tutorials and tutorials files for optistruct? OS-2005/2010/2030 download this free book https://altairuniversity.com/free-ebooks-2/free-ebook-practical-aspects-of-structural-optimization-a-study-guide/
  10. Привет, Катерина=) а ты проходила туториалы по оптимизации? =)
  11. i have only one idea. you should create line B and project to surface. after you will remesh and delete extra face.
  12. you simulate your body by solid elements, but solid elements have only translation DOFs. and your body moved like a rigid body. what type analysis did you do? explain, pls, your simulate case.
  13. With the density method, the material density of each element is directly used as the design variable and varies continuously between 0 and 1; these represent the state of void and solid, respectively. Intermediate values of density represent fictitious material. The stiffness of the material is assumed to be linearly dependent on the density. This material formulation is consistent with our understanding of common materials. For example, steel, which is denser than aluminium, is stronger than aluminium. Following this logic, the representation of fictitious material at intermediate densities does reflect engineering intuitions. In general, the optimal solution of problems involves large gray areas of intermediate densities in the structural domain. Such solutions are not meaningful when we are looking for the topology of a given material, and not meaningful when considering the use of different materials within the design space. Therefore, techniques need to be introduced to penalize intermediate densities and to force the final design to be represented by densities of 0 or 1 for each element. The penalization technique used is the “power law representation of elasticity properties,” which can be expressed for any solid 3D or 2D element as follows: K(r) =K* ρ^p where K and K represent the penalized and the real stiffness matrix of an element, respectively, ρ is the density and p the penalization factor which is always greater than 1. In OptiStruct, the DISCRETE parameter corresponds to (p - 1). DISCRETE can be defined on the DOPTPRM bulk data entry. P usually takes a value between 2.0 and 4.0. For example, compared to the non-penalized formulation (which is equivalent to p=1) at ρ=0.3, p=2 reduces the stiffness of the element from 0.3 to 0.09 times the stiffness of the fully dense element. The default DISCRETE is 1.0 for shell dominant structures, and 2.0 for solids dominant structures (the dominance is defined by the proportion of number of elements). An additional parameter, DISCRT1D, can also be defined on the 50
  14. i've got the answer from support team. Hi, Marat! I figured it out. Before clicking “Apply” in HyperView, you need to select the component “design”. Otherwise, the component “nondesign” has element density 1 because its thickness was not changed during optimization. The newer version of OptiStruct is not simply replacing the term “element thickness” with “element density”, but the definition of those two are different. “Element density” means the percentage of material variation is used, so the upper bound of this result is always 1. In this example, “1” means 0.3mm base thickness + 100%*0.7mm variation thickness = 1mm; “0.5” means 0.3mm base thickness + 50%*0.7mm variation thickness = 0.65mm Two pictures below show the difference of plotting the contour with “design” component selected and not. They are the same result, and they look different because the color of nondesign component. Thanks, Yuhao He | Senior Project Engineer yhe@altair.com | Yuhao's Secure FileDrop Altair Engineering
  15. @tinh another one question, pls! i can't see element thickness. i am doing optimization tutorial os 2020, but i haven't result "element thickness". i have just had in my solution "base thickness". and it doesn't change from iteration to iteration.
  16. at first -which units did you use? -is it necessary to make model for radioss solver?
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