# sinusoidal acceleration

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• Last Post 05 January 2020
ansys8 posted this 04 January 2020

hi everyone

i'm working on ansys workbench v.15

how can i do sinusoidal acceleration due to an applied sinusoidal force?

peteroznewman posted this 05 January 2020

That depends on what kind of results you want to see.

If you want the steady state sinusoidal response of the structure to a continuous sinusoidal force, that is called Harmonic Response. In a Harmonic Response analysis, when you apply a Force load to the structure, your input is the amplitude of the sinusoidal force.  Under Analysis Settings, you tell the solver the range of frequencies of the sinusoidal force that you want it to compute the response for.  Result plots such as acceleration are the amplitude of the structure response at the selected frequency. This is probably what you are looking for.

An important input to dynamics models is Damping.  Under Analysis Settings are Damping Controls. Don't leave them at the default of 0 damping as that is not realistic. Do you know what to use or damping on your structure?

You can save some time computing this result if you do a Modal analysis first, then drag and drop the Harmonic Response analysis onto the Solution cell of the Modal analysis. That creates a Modal Superposition (MSUP) solution.  There are some requirements on including a sufficient number of modes to get an accurate solution.

Anytime you do a dynamic analysis of any kind, it is always best to first perform a Modal analysis, even if you don't link it, just so you know the first natural frequency of the structure. If the Harmonic Response analysis setting includes the first natural frequency in the range of frequencies, then you will be exciting the structure at resonance, and the values put in the damping controls will have a large effect on the peak acceleration response at the resonant frequency.

Note that Harmonic Response (and Modal) analysis is a Linear analysis, which means there are no nonlinear effects: large deflection, frictional contact or material nonlinearity such as plasticity.

Sometimes the Transient Structural response is what is wanted. How a quiescent structure responds over time to that first oscillation of a force sinusoid. You probably don't want that, but that can include nonlinear effects.

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