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How to apply prescribed displacement harmonic perturbation?
Posted Mar 10, 2016, 1:43 a.m. EST Geometry, Structural Mechanics Version 5.0 1 Reply
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Hi
I am new to COMSOL. My model is simplified to a cantilever beam subject to an external excitation which is a sine pulse of constant displacement of 0.5mm with a frequency ranging from 5-50 Hz. I try to use the prescribed displacement with harmonic perturbation option but I am facing problems. First I don't understand which boundary to apply the prescribed load to, and secondly I am unable to understand how the harmonic perturbation option works.
I am using Solid Mechanics module with frequency-domain modal study, creating a cantilevered beam of dimensions 100*10*1 mm (Just to play around with) and doing a frequency sweep from 5-50 Hz.
Any help is appreciated.
Thanks
Rohan
I am new to COMSOL. My model is simplified to a cantilever beam subject to an external excitation which is a sine pulse of constant displacement of 0.5mm with a frequency ranging from 5-50 Hz. I try to use the prescribed displacement with harmonic perturbation option but I am facing problems. First I don't understand which boundary to apply the prescribed load to, and secondly I am unable to understand how the harmonic perturbation option works.
I am using Solid Mechanics module with frequency-domain modal study, creating a cantilevered beam of dimensions 100*10*1 mm (Just to play around with) and doing a frequency sweep from 5-50 Hz.
Any help is appreciated.
Thanks
Rohan
1 Reply Last Post Mar 11, 2016, 1:56 a.m. EST
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Posted:
8 years ago
Hi,
Whether to enter the excitation as Harmonic perturbation or not depends on details in the study settings.
This is described in the section 'Structural Mechanics Modeling' ->' Study types' -> 'Harmonic perturbation' in the documentation.
The short answer (which does not cover all cases) is that 'Harmonic perturbation' should be used for a mode superposition analysis, but not for a direct frequency domain analysis. In either case, you only enter the amplitude and phase of the excitation. The harmonic part is implicit.
Look for example at the 'elbow_bracket' model in the Application Library.
Regards,
Henrik
Whether to enter the excitation as Harmonic perturbation or not depends on details in the study settings.
This is described in the section 'Structural Mechanics Modeling' ->' Study types' -> 'Harmonic perturbation' in the documentation.
The short answer (which does not cover all cases) is that 'Harmonic perturbation' should be used for a mode superposition analysis, but not for a direct frequency domain analysis. In either case, you only enter the amplitude and phase of the excitation. The harmonic part is implicit.
Look for example at the 'elbow_bracket' model in the Application Library.
Regards,
Henrik