differences between harmonic analysis ans spectrum analysis 1

[mikycampo]

Dear All,

can someone explain me the theoretical difference between an HARMONIC RESPONSE ANALYSIS and a SPECTRUM ANALYSIS?

I'm going to analyse a piping system subject to acoustic inducted forces, given to me in Force-vs-frequency form.

Thanks again,
Michelebold

 

[Transient1]

Michele Bold,

It sounds like your question is better suited for the finite element analysis or ANSYS forums. A harmonic analysis is the sustained cylic response(a harmonic response) to any sustained cyclic load. A spectrum analysis considers the various displacements and stresses in a system due to a random or time-dependent load condition. A spectrrum analyis takes into account all the modes of the system in the frequency range of interest. If the force varies continuously with frequency, it sounds like a spectrum analysis is appropriate. However, if in the frequency range of interest there is only one dominant mode of your system, then a harmonic analysis for the force at that frequency may give you enough information.

The theory behind the two type of analyses are related, but a bit lengthier than a short post can elaborate on. If you can get your hands on the ANSYS theory guide (google) or ANSYS structural guide, both do an excellent job talking about these type of analyses.

Chris

 

[jeyaselvan]

Harmonic response analysis : refers to the resposne studies of the system for single excitation at a time.

Spectral analysis : Compilation of results from the harmonic analysis over a frequency ramge. This could also refer to the response of the system with random excitation input (where all excitation frequencies exist at any point of time). Spectral analysis is a very generic term.