Regarding Stress Carry over from Pretension or Pre loaded NL model to FRF

josephmalvinraj

For understanding stress carryover in coupled pretension+frequency response we took a standard example ( attached reference file ). we imported our model in the example file so that the deck set will be unchanged. 

Later we changed that to a large displacement model as it gives the desired deformation of our rubber bush. other than this no changes were made in the deck.

we are unable to observe the carryover of stress from NL static analysis to frequency response. have attached the required (.fem) files for your reference. We are expecting the stress strain and internal forces to be carried forward to frequency response.

Please resolve this at the earliest. 

 

Reference.fem : Pre load_NLSTAT_MFRF.fem.

with_large_disp: previous deck changed to large disp.

Pre load_NLSTAT_MFRF.fem

With_large_disp.fem

Adriano_Koga

I've never quite tried this approach.

But looking at the documentation, i've found this:

 

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.

 

 

 

Prestressed Linear Analysis.pdf