Dynamic Frequency Analysis

[ksarita20]

hi all,


I need to perform a dynamic frequency analysis on a fixture for which the part is exposed to 5g vibration load which varies from 50-1000 hz. i need to determine the stresses, fatigue life and natural frequencies of the fixture.


I havevery little knowledge about the dynamic capabilities of Pro/FEA. Can any one help me out with this.


First of all, how will we know that we have to do dynamic frequency analysis. what is the exact differenence between dynamic time and dynamic frequency anal.


The process which i know ( i mean which i read in the manual) is as follows:


1. Define the constrains, material and apply the Gravity in the direction prefered.


2. Perform the modal analysis and find the frequencies at different mode shapes.


3. Perform a dynamic frequency anal for all frequencies and find the frequency atwhich the stress are high. before perfoming the anal, we have to define the load as a function of time. this is what i didnt understand how to do for my particular problem.


4. Perform the dynamic analyis at the freuency at which the stresses are high and determine the stress and displacment contours. For this anal also, the load function is defined as in previous step.


I think this proceedure is correct, but i donn why i am performing these steps and the exact method to define the load function


Can any one please help me in this regard.


Thanks in advance.


Sari
Edited by: ksarita20

 

[Nose Bleed]

Who wrote that tutorial???

 

[Israr]

Will send you an example of dynamic freq. analysis, if you give me your email address.


Israr

 

[rodgiles]

Dynamic frequency analysis with an acceleration input is called a 'base excitation' analysis. You don't need to apply a static load in order to carry out the analysis.


YouMUST specify a damping factor for your analysis otherwise your results will be meaningless.It is specified in terms of a percentage of critical damping. For most metallic structures values between 1 and 5% are common.


In orderto review the frequency response you MUST createuser defined measures; there are nopre-defined measures fordynamic analyses. Make sure thatyou check the 'time/frequency' option for stress, displacement otherwise the measures you create will only be valid for static not dynamic analysis.


Elite Consulting run two-day vibration analysis courses in the UK (sorry about the plug!)


Regards,


Rod Giles


Elite Consulting Ltd.

 

[ksarita20]

hi all,


thanks for your suggestions.


Nose Bleed, why did you ask like that, so you think the steps i wrote are not correct.


ISrar, my mail id is [email protected]. I will be very thankful if you can send me the tutorials. And if it can tell me why we are doing each step then it will be more useful.


Rodgiles, i defined the reqired measures and also defined a damping factor of 2%. So now do you think the prodecure is OK.


Please guide me.


THanks in advance.


Sari

 

[Foxian]

Isvar,


Could you please send me the tutorial aswell, looking to carry this analysis out aswell,


Email Address: [email protected]





Foxian

 

[Nose Bleed]

Ditto,


That's why I asked who wrote the tutorial...

 

[ksarita20]

Nose Bleed,


I got them from PTC customer education manual ( my friends book). thought the words are not same, the process is similar. my friend explained me on a phone, i didnt see the book. SO do you think i understood wrong. IF so can you please give me the correct procedure.


Isvar, i hope you remember that you have to mail me the tutorial. My id [email protected]


I desperatly need this. i have start my work on tuesday on this project. So please help me out.


thanks in advance


Sari

 

[chase83]

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[miya]

Suggested Technique on Performing a Dynamic Time and Frequency Analysis

http://www.ptc.com/cs/cs_25/howto/mst2477/mst2477.htm

 

[chase83]

hello miya,

please post the article. I don't have the permission to watch this article.

Thanks,
christian

 

[Israr]

Rod Giles has been my teacher and to learn MDO and the subject analysis Elite Consulting is the best institute in the world.

 

[chase83]

hello israr,



can you answer my question?

How can I set the load as a function of time?

christian

 

[santosh_cipet]

hi there i need a step guide or soft copy data about to work ahead with pro Mould design


i'm failed to work with it





can i have it by you