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NESTED LOADING in OPTISTRUCT

Altair Forum User

Is it possible to apply and run nested preloads.

Like, if i have 4 subcases and i want to carry the result of subcase 1 on 2 and so on.

subcase 1 as preload in subcase 2

subcase 2 as preload in subcase 3

subcase 3 as preload in subcase 4.

I tried to get result by taking types: Linear and Quasi-Static Analysis but in-vain. As per my best knowledge it is possible in Nastran, Ansys and Abaqus with Quasi-Static Analysis type.

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Rahul_P1

Pritam,

Did you try prestressed analysis first with just two of your subcases? is that what you were looking for? also are all your loadcases linear static? in the Hyperworks help see

Altair OptiStruct > User's Guide > Structural Finite Element Analysis > Loads and Boundary Conditions:

Prestressed Analysis

Altair Forum User

I believe what you are looking for is the 'CNTNLSUB' option. You can activate it by card editing the desired loadstep and checking 'CNTNLSUB', which is right below 'ANALYSIS'.

Rahul_P1

Yes, but please note CNTNLSUB is for non linear loadcases only,

Altair Forum User

CNTNLSUB is for non-linear subcases that i understand how its works. But when i was tring for Linear Static :

Pretenstion load as STATSUB(PRETENS) in 1st load case

and later : 1st Load case as STATSUB(PRELOAD)to 2nd Load case and so on till 4th subcase.

But during the run, Optistruct run came out by giving error Nested Looping, So i thought, i can clarify whether optistruct supports nested looping or not as in the case of NASTRAN.

Later, i decide to run with work with CNTNLSUB and changing load cases for LINEAR STATIC too as it's the only work around option.

Thanks for response.