×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Moment of inertia - system of bodies

Moment of inertia - system of bodies

Moment of inertia - system of bodies

(OP)
Hello,

I have a question concerning moment of inertia (kg*m^2) of a system of bodies. As seen in the picture attached, I am dealing with a crank/con rod mechanism that operates by applying a moment via. motor about the crank centerline (crank is on top in this application). The crank moves vertically while the long con rod just pivots. The range of motion is just 0 to 180 degrees.

What I need to do is calculate the moment of inertia of the system with respect to the crank centerline throughout the range of motion of the system. I am using NX9 with limited license capability, so hopefully I am able to do it. I already have the assembly constrained in the assembly such that I just have to adjust an angle constraint and the whole assembly moves accordingly. I am having a hard time because I don't know how to find the inertia with respect to the constraints + gravity/orientation

Thoughts?
Thank you

RE: Moment of inertia - system of bodies

First of all, gravity doesn't affect moments of inertia, does it (if I remember my high-school physics correctly).

Generally, I think NX will report moments relative to the WCS axes. So, set the WCS to have its Z-axis along the centerline of your crank, and NX should give you the answer you want.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources