Modal effective mass
Kindly find the attached out file
In effective modal mass i am getting my total mass in translation direction
Why not in rotation of X direction?
Is the unit different when it comes to translation and rotation ?
Thanks for your help
<?xml version="1.0" encoding="UTF-8"?>
Answers
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The Modal Effective mass in the Trans X, Y and Z directions and Rotational X, Y and Z direction have the same units.
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Altair Forum User said:
The Modal Effective mass in the Trans X, Y and Z directions and Rotational X, Y and Z direction have the same units.
Thanks for reply but in total mass in rotational directions why it is not equal to total mass? in translation i get my total mass equal to system mass but in rotational it shows 250kg which is more than my over all system mass
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The Modal Effective Mass is a measure of how much mass is associated with each mode.So for the more prominent mode you will get more mass.
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Thanks for the answer Rahul
Yet still why do i see high mass value in rotation direction
Mass value in rotation direction is higher than my system mass
kindly clarify
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I see you have requested only first two modes, which might be missing critical data and under predicting response of the system.I request you to run with ND as 25 modes in EIGRL card and then evaluate the response in out file.
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Hi Rahul
I am trying to co relate analysis calculation vs theoretical calculation so i took simple 2dof system so it will have oly 2 natural frequencies
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have a look at my model setup and let me know why rotational mass comes wrong
<?xml version="1.0" encoding="UTF-8"?>
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Can you share .out file of the run?
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have a look at this my total mass is 4kg in translation i get my total mass but in rotation i get 250 kg
Kindly clarify whats wrong
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Thanks for sharing .out file.Can you also share .fem file to try this on latest version.
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You can check my trial model.
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Hi
I checked your model there is no stiffness assigned for CELAS2 and you have created PELAS1 AND THE ELEMENTS HAVE NOT BEEN ASSIGNED STIFNNESS?
I have attached my model run the same and let me know what mistake has been made
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Also let me know if i could contact you through phone
I want to sort this out sooner
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Why you are expecting translation and rotation to be same.The Modal Effective Mass is a measure of how much mass is associated with each mode.
Please try effmass on other model to understand its output.
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I have tried and its not same
It would be clear if we could have chat or call to explain clearly what is my issue
Let me know
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