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[StudenteAnsys]

Hello everyone, I'm trying to compute the effects of gravity load on the frequencies of my system.

My system is a beam with a fix-end and free-end, where I placed a mass rigidly connected to the beam.

Through Modal Analysis I managed to obtain the frequency of the system neglecting the presence of gravitational acceleration, but for my purpose I need to include this effect in my results and obtain the response spectrum of my system.

Can anyone help me?

[Erik Kostson]

 

 

 

Hi

What you have (mass and gravity load) will cause a pre-stress (compressive load/stress will lower beam frequency for its bending modes) – see here for some theory details – the effect is called stress softening or stiffening (if tensile load /stress is applied to beam say)

https://innovationspace.ansys.com/courses/wp-content/uploads/sites/5/2020/10/Lesson4_ApplicationsOfLargeDeformation.pdf

This can be captured with a pre-stress modal – see here in our course for more details.

https://innovationspace.ansys.com/courses/courses/modal-analysis-in-ansys-mechanical/lessons/how-to-perform-prestressed-modal-analysis-lesson-2-2/

Also look through the rest of the courses (response spectrum)

https://innovationspace.ansys.com/product/modal-analysis-in-ansys-mechanical/

https://innovationspace.ansys.com/courses/courses/single-point-response-spectrum-analysis-using-ansys-mechanical/lessons/how-to-perform-response-spectrum-analysis-lesson-1/

Seacrh for more courses there.

You can perhaps combine results later (so add gravity with SRSS response spectrum results say) - look on solution combination.

All the best and good luck with your studies

Erik

 

 

 

 

[StudenteAnsys]

Thank you very much Erik!