Learning Forum

[FU HSIEN CHOO]

Hi, I am working on a static analysis that requires 2 combining different models due to sequential loading. Example, the first model consists of 2 bodies loaded in vertical and in the second model (consisting of the same 2 bodies from first model, plus 1 additional body) and additional lateral load is applied to the new third body. Material is linear and both models are pinned at the bottom. In the first model I have actually modelled all the 3 bodies but suppressed the body which is to be used in second model. Then I duplicated the Static Structural in Workbench and unsuppressed the third body and applied the lateral load. I am unable to combine these 2 models.
 
Can anyone assist to advise the best method to perform such analysis? In addition, if the material is bilinear, is combination still possible?


I have made a sample model but I am unable upload it here.

 

[Aurojyoti Prusty]

Hi Fu Hsien,

I suppose you want to see the effect of the two loading on your model (combining all bodies) at the same time ?. If that is true,  you can apply the two load in two different steps which can be achieved in the analysis settings of the static structural tree. That would be more realistic than combining two different bodies and applying different loadings. Please let us know if that is what want to do or you have specific requirements of applying the two load in a sequential manner.

Thanks,

Aurojyoti 

[FU HSIEN CHOO]

Hi Aurojyoti,

I missed to upload the first snapshot. Basically i need to consider lock-in stress analysis. In model 1, axial stress is already present due to vertical load, subsequently additional structure is added to model 1. Model 2 shows the additional body and lateral load is applied to the new model.

The problem I need to solve is a structure which is marginally overstress during some rare event load, and it needs to be strengthened with additional structure before the rare event load happens again. Hence the lock-in stress of the original load need to be considered. Is there a way where Mechanical 'suppress' the additional strengthening body for initial stage and then 'unsuppress' it during the rare event load?

[mohan.urs]

Hey FU HSIEN CHOO,

Now that the problem is clear i would suggest using element birth and death (which is similar to supressing and unsuppressing a body in different steps). 

You can access the ansys help page for the same here 17.6.4.7. Element Birth and Death (ansys.com)

To get you started, Do a multistep analysis where you set the 3rd body to be dead and give appropriate loads to 1st and 2nd body (this 3rd body won't interfere with the first load step).

Next in the 2nd load step activate the 3rd body using the step controls in element birth and death and now give the loads for the same body.

Thankyou.

[FU HSIEN CHOO]

Hi Mohan,

Thanks for the assistance. Greatly appreciated. If we use bilinear material for this condition, is the analysis still valid?