Attaching 2 Objects + moment of inertia with/without point mass

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  • Last Post 24 January 2020
mehmoodkhan0345 posted this 24 January 2020

Hello Everyone,  i was trying to keep this question short but i really couldn't. sorry about that but please have a look and help if possible.

I am a student(bad at software) and trying to make a simple geometry of a beam(flexible),  To find the deformation/natural frequency/moment of inertia/deflection, etc (using harmonic response). I need to use Ansys.(i never used Ansys before but trying to learn it from last 2 days). I have few questions,(one about the space claim tutorial and one general, since posting it in spaceclaim tutorial section so need to mention this) posted some pictures as well for better understanding my question and to keep it simple.

When i create a bar with default material structural steel, it gives me the value of moment of Inertia, mass of object etc. I fixed one side of the bar and want to rotate it horizontally (say Z-axis). i dont know what does this Ip1,Ip2,Ip3 means. See the picture.

 

Question 1:  Which inertia value should i take according to picture? and what does this Ip1,Ip2,Ip3 means? (using static structural)

 

 

Next: SpaceClaim tutorial:

I want to add point mass to the end of the rod and then check the deformation, but when I add the point mass it doesn't show the value of the moment of inertia.

saw some tutorials and found a way to get the moment of inertia value for object with point mass but that requires another part attached to the geometry. i have tried to attach this small piece to have 2 geometry files to follow the tutorial but I couldn't attach it, someone i know used ansys 4-5 years ago said mate option will merge it but I can't seem to find it.  then i was watching this "Tutorial i was trying to follow"

I used merge/split, it got merged and became one with the bar. i tried to draw that small piece at the end but it got attached automatically etc.

See the picture, in picture 3 it shows the position where i want to stick this object with its own point mass. any side of the long bar is fine as long as that small piece can stick .

2nd Question: Can anyone tell me how to attach the small piece at the end but with the individual separate values so i can add point mass to the small piece and check the effect on the beam as a whole.

 

Thank you very much.

sorry for the lengthy post. and Sorry if we are not allowed to post external links like youtube, it was not mentioned in guidelines for posting so i just did. 

 

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peteroznewman posted this 24 January 2020

SpaceClaim

It seems like a bug, but the moment of inertia only displays correctly if the units are set to mm.  If you add material to the base solid, then they unite into a single solid and you don't have to worry about connecting them. Just select a face, click the Sketch button, draw a rectangle or even just a line to split the face, then use the Pull tool to add material.

Point Mass

You don't add that in SpaceClaim, you add that in Mechanical once you begin an analysis. You do that by right click on Geometry > Insert > Point Mass.

Moment of Inertia

If you build a model in ANSYS to solve a Harmonic Response, you don't need to know the Moment of Inertia of any parts. ANSYS does the work for you.  If you want to use textbook equations and calculate the response by hand, then you do need to know the Moment of Inertia.

mehmoodkhan0345 posted this 24 January 2020

thank you for your reply.

i have been reading your comments all over the forum for last  couple of days and i have learned many things, at least got some idea about several things.

thankyou for this info about moment of inertia only displayed correctly in mm, but my project is in between somewhere where i need to get all the values , so i can decide which servo motor is good enough to rotate the bar and whats its limitations. i think to some extent i understand but i have one more question. i will try some more tutorials found on youtube and will get back here if i need...thank you

 

 

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