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forced vibration of a cantilever beam - width effect in COMSOL and ANSYS
Posted Jun 9, 2015, 1:54 p.m. EDT Modeling Tools & Definitions, Parameters, Variables, & Functions, Studies & Solvers, Structural Mechanics Version 5.0 2 Replies
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Dear All,
I am simulating a cantilever beam with L=28mm, W=20mm, t= 0.82mm.
And also another cantilever beam with L=28mm, W=2mm, t= 0.82mm.
Under harmonic pressure of 6pa.
First -COMSOL results in resonance are different with ANSYS. Huge difference. And none of them give the result of forced harmonic excitation in the books.
Second- they both give more defelction for the wider plate in resonance.
In static analysis they both give the same result and the wider plate has less defelction than the narrower one but in frequency analysis the problem described above appears.
As the plate gets wider, the deflection should decrease not increase right?
Thank you,
Edvin
I am simulating a cantilever beam with L=28mm, W=20mm, t= 0.82mm.
And also another cantilever beam with L=28mm, W=2mm, t= 0.82mm.
Under harmonic pressure of 6pa.
First -COMSOL results in resonance are different with ANSYS. Huge difference. And none of them give the result of forced harmonic excitation in the books.
Second- they both give more defelction for the wider plate in resonance.
In static analysis they both give the same result and the wider plate has less defelction than the narrower one but in frequency analysis the problem described above appears.
As the plate gets wider, the deflection should decrease not increase right?
Thank you,
Edvin
2 Replies Last Post Jun 10, 2015, 6:06 p.m. EDT
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Posted:
9 years ago
Hi
that might happen, that software tools give different results, but there are mostly a rationale explanation, some hypothesis behind the models settings or some other issue.
Anyhow, I do not see how we out here can understand what is wrong as you do not define fully you model: for me there are essential material data, physics type, BC conditions that are missing from above.
So far I have hardly ever caught COMSOL giving me "physically wrong results", sometimes they do differ from other SW tools or publications, but each time I have, after digging deeper into the models, found some good explanations.
But sometimes errors might happen, also for the best tool ;) so I would suggest that you dig a bit deeper under the hood, and if you want help from us out here, be a bit more precise in your description
--
Good luck
Ivar
that might happen, that software tools give different results, but there are mostly a rationale explanation, some hypothesis behind the models settings or some other issue.
Anyhow, I do not see how we out here can understand what is wrong as you do not define fully you model: for me there are essential material data, physics type, BC conditions that are missing from above.
So far I have hardly ever caught COMSOL giving me "physically wrong results", sometimes they do differ from other SW tools or publications, but each time I have, after digging deeper into the models, found some good explanations.
But sometimes errors might happen, also for the best tool ;) so I would suggest that you dig a bit deeper under the hood, and if you want help from us out here, be a bit more precise in your description
--
Good luck
Ivar
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Posted:
9 years ago
Hi Ivar,
Thank you for your reply.
I have uploaded my file. I have moved one step forward and let's forget to compare with other software.
The model is acoustic-structure interaction.
I want to see the deflection of a cantilever plate under 6pa acoustic domain.
Everything is defined in the model.
Two cantilever's are : 1- L=28mm , w=20mm, t= 0.82mm
2- L=28mm, w=2mm, t=0.82mm
The eigenfreq. of the wider plate is around 392hz and the narrower one around 378hz.
In this model the deflection of the wider plate around it's eigenfreq is more than the narrower one around it's eigenfrequency.
Based on vibration theory " deflection in forced harmonic analysis" since the wider one has more mass it should deflect less, and based on "static analysis" it also should deflect less than the narrower one.
In static analysis I have tested it is ok but in acoustic-structure module I have this problem.
I appreciate your help in this matter.
Regards,
Edvin
Thank you for your reply.
I have uploaded my file. I have moved one step forward and let's forget to compare with other software.
The model is acoustic-structure interaction.
I want to see the deflection of a cantilever plate under 6pa acoustic domain.
Everything is defined in the model.
Two cantilever's are : 1- L=28mm , w=20mm, t= 0.82mm
2- L=28mm, w=2mm, t=0.82mm
The eigenfreq. of the wider plate is around 392hz and the narrower one around 378hz.
In this model the deflection of the wider plate around it's eigenfreq is more than the narrower one around it's eigenfrequency.
Based on vibration theory " deflection in forced harmonic analysis" since the wider one has more mass it should deflect less, and based on "static analysis" it also should deflect less than the narrower one.
In static analysis I have tested it is ok but in acoustic-structure module I have this problem.
I appreciate your help in this matter.
Regards,
Edvin