Inertia Relief Analysis - with SUPORT boundary conditions

srinivas rallabandi_21059
srinivas rallabandi_21059 Altair Community Member
edited October 9 in Community Q&A

Hi there 

I am performing inertia relief analysis in simsolid. Looking for option how to setup SUPORT boundary conditions or virtual constraints.

How simsolid results compare when the user specify boundary conditions against other solver

 

I tried to solve the model with inertia relief without boundary conditions assuming the solver assumes 

I have the following warning message before submitting the job for analysis

image

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Answers

  • Girish Mudigonda_21018
    Girish Mudigonda_21018
    Altair Employee
    edited October 2

    Hi,

    You can ignore this warning and proceed to run the solution. SimSolid will run with the inertia relief approach.

  • srinivas rallabandi_21059
    srinivas rallabandi_21059 Altair Community Member
    edited October 2

    Girish

    thank you for your inputs. Before I work on my actual problem I tried on the simple part to see  how close the results  are wrt to other solvers

    • I used nastran as the solver with auto-support (param,inrel,-2) enabled where the system picks the bcs here and solved for inertia relief
    • I applied 100N on each mount in the vertical direction 
    • I solved in simsolid as  would like  to know why there is a difference in stress. I also got few inputs from altair support where the solution settings needs to be tweaked but still the stress results are not close. 
    • I am interested if the % error is minimal . but its not in my case
    • Below are my plots for your reference 

     

    Loads

    image

    Nastran Stress plot (Vonmises)

    image

    Simsolid Stress plot (Vonmises)

    image

     

    what are the optimum settings I need to use . How I know my optimized settings ?

    image

     

    I also tried custom settings as suggested , the results are not close 

    image

     

  • Girish Mudigonda_21018
    Girish Mudigonda_21018
    Altair Employee
    edited October 8

    Hi Srinivas,

    Do you have two elements through the thickness? Are you using second order tetras in Nastran?

    Can you also try to refine the result plot on the long frame in SimSolid?

  • srinivas rallabandi_21059
    srinivas rallabandi_21059 Altair Community Member
    edited October 8
    Girish Mudigonda_21018 said:

    Hi Srinivas,

    Do you have two elements through the thickness? Are you using second order tetras in Nastran?

    Can you also try to refine the result plot on the long frame in SimSolid?

    Hi girish 

    what do you meant by refine the result plot ?

  • srinivas rallabandi_21059
    srinivas rallabandi_21059 Altair Community Member
    edited October 8

    Do we have any verification problem in inertia relief  against optistruct (inertia relief) ? 

     

  • Girish Mudigonda_21018
    Girish Mudigonda_21018
    Altair Employee
    edited October 8
    srinivas rallabandi_21059 said:

    Hi girish 

    what do you meant by refine the result plot ?

    When you have the contour plotted, right-click on the plot to refine the result plot.

  • srinivas rallabandi_21059
    srinivas rallabandi_21059 Altair Community Member
    edited October 9
    Girish Mudigonda_21018 said:

    Hi Srinivas,

    Do you have two elements through the thickness? Are you using second order tetras in Nastran?

    Can you also try to refine the result plot on the long frame in SimSolid?

    Yes I am using second order elements in Nastran 

     I tried to refine the plot in the simsolid , not much difference though in the stress contour or magnitude of stress 

     

  • Girish Mudigonda_21018
    Girish Mudigonda_21018
    Altair Employee
    edited October 9
    srinivas rallabandi_21059 said:

    Yes I am using second order elements in Nastran 

     I tried to refine the plot in the simsolid , not much difference though in the stress contour or magnitude of stress 

     

    Can you please try to send the model to support, so someone can take a closer look and help here?

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