Superimposing preload stress field on all linear transient result increments

AmirMar

Dear All,

I hope you can assist me with this question.

I have a linear transient analysis with a nonlinear preload. The nonlinear preload induces stress field.

However the solution of the linear transient case is relative to the beginning of the step. I would like to take each increment and add the nonlinear result. Is it possible to do that?

Thank you,

Amir

Adriano A. Koga

Found this in the OptiStruct documentation. In HV you should be able to create a derived loadstep with superposition.

 

Results

All results that are supported for regular structural linear analyses are also available in the corresponding prestressed linear analyses.

It is important to note that, while the prestressed linear analysis includes the effects of preloading as a weakening or a stiffening of the structure, the results from the prestressed analysis do not include the preloading results. For example, the displacements from prestressed linear static analysis do not include the preloading displacements. In order to get the overall deflection/stresses of the structure, the displacements/stresses from the prestressed linear analyses have to be carefully superposed with the preloading displacements/stresses while post-processing. Particularly, while post-processing complex results from prestressed direct FRF, the correct approach would be to first obtain the complex results for a certain phase and then superpose the appropriate preloading result. Any other superposing approach would lead to incorrect results.

AmirMar

Hi Adriano,

Thank you for the response.
As you can see, the documentation states that: " the results from the prestressed analysis do not include the preloading results" and this is indeed the problem I try to overcome. I guess that many other user might want to do that as well.
I couldn't find a way to perform this superposition in HV for a step that includes several frames. The derived load step only creates a single load step with a single frame in it.

Can you please explain how can I do this superposition for a preloaded transient analysis?

Thank you,
Amir

ginger no

AmirMar said:

Hi Adriano,

Thank you for the response.
As you can see, the documentation states that: " the results from the prestressed analysis do not include the preloading results" and this is indeed the problem I try to overcome. I guess that many other user might want to do that as well.
I couldn't find a way to perform this superposition in HV for a step that includes several frames. The derived load step only creates a single load step with a single frame in it.

Can you please explain how can I do this superposition for a preloaded transient analysis?

Thank you,
Amir

Hi Amirmar

so I have this similar problem with the first case is linear static. I just want to use the last frame to superpose the 2nd case, how could i this "derived loadstep"