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Posts posted by Korosh

  1. Hello Dear friends

    In the attached model, there is an error in the energy balance(99%)

    I know that this error is related to how I define  Material, Contact or Time step.

    But I don't know which parameter in the file I need to change to fix the Energy error.

    Can anyone advise on the problem of energy balance?


  2. Hi my friend

    With your good help I was able to solve Mass Err.

    But there is still a fault with the energy error(ERR= -99%).I changed some parameter in my model(Contact,Material , ...).However, as soon as a collision occurs, the amount of energy increases.If possible, please guide me to fix this issue.

    Is there an educational film about this?

    Best regards and I hope to meet my good friends in the future.

  3. my Dear,

    I have 2 question. 

    1) in my Model , mean Mesh size 7mm , Density : 9.85E-9 ton/l , E=210000 Mpa, i want to calculate Nodal time step by this equation: tn =L/(E/Density)^0.5

    But i don't know , How to choose the right unit?

    2) if after check Out file, and see increase %ERR= - 99% , is that simulation is good or bad?

    I attached two different Out file,Please checked and guide me.

    best regards

  4. Hi My dear

    It was already mentioned when using 2D Mesh for sheet metal's , we have to use the Midsurface in making the mesh.

    so If I'm going to creat 2D mesh for two sheet metal's with thickness of one and two millimeters , the real distance between two midsurf should be " 1.5 mm" (In accordance with Appendix)

    In the Example in the E_Book , tow Pats have thickness of one and two millimeters , While the distance  of each other is about 3 mm.

    Despite this, Is the analysis presented in the example correct?





  5. Hi

    Suppose, for side crush of a car, after performing the analysis(Create mesh, define MAT, Prop, Contact ,.....  I will Decide to change the thickness of some sheet's, so , I should define offset for Sheet's that have a change in thickness and then i should change some parameter's such as Contact, Spot weld , ....

    Therefor, in analyzing a car that includes many hundreds of mesh, These changes will be very time consuming and costly.

    Is there a good solution in this regard?

  6. Hi My dear

    I sent Two Cad file ( Little Area of Rear Frame )

    Each part have 2 mm Thickness and both direction are inwards.

    So i should be ,create 1 mm Offset for each parts and then i will create mesh.

    for example , if after create mesh and Crush Analysing , the result not acceptable , and i want to change thickness to new value 2.5 mm ,then Reanalyse Crush test.

    In this level , do i have change  Mesh of tow parts with new offset (1.25 mm) and change all Spot weld , contact ,... ?

    (Consider that for Real side crush i have 52 different parts of car)

    Best regards



  7. Hi my friends.

    I have some CAD Data( 3D Drawing, face of car's , With Thickness=0.0).

    some file's have overlap and Some File's have offset (thickness).

    when I define property , the mesh is known with Mid Surface, I think that isn't good idea for create mesh

    in attachment , is described at Fig.1 and fig.2

    in Fig.1 two surface haven;t offset , but in Fig.2 two surface have offset (3mm)

    My problem:

    I think ,at fig.1,the  first create mesh for every surface then define Property ( Thick part.A =2mm , Part.B=0.7mm)

    But at Fig.2 , i don't know , can i create mesh according to the last method ( same as Fig.1) ?Pic-1.thumb.png.43498e26ec94f023125eadc934bd61a7.png


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