moment of inertia
moment of inertia
(OP)
Need help calculating moment of inertia. I need to flip my part and frame 90deg. Im hoping someone would be kind enough to reply with the formula needed to calculate it.
I think the uploaded drawing should be enough.
PS I know my CAD software (SolidWorks) can calculate this but SolidWorks can't this time because some of the parts have an assigned mass prop. and not a material.
Thanks
I think the uploaded drawing should be enough.
PS I know my CAD software (SolidWorks) can calculate this but SolidWorks can't this time because some of the parts have an assigned mass prop. and not a material.
Thanks
Certified SolidWorks Associate
SW2009 X64 SP 1.0
Dell Precision T5400
Nvidia Quadro FX 5600
Xeon 2.5GHz Quad Core, 4GB RAM
XP Pro X64 SP2.0





RE: moment of inertia
Ix'x' = Iyy
Iy'y' = Ixx
no?
RE: moment of inertia
Do you know the rotation axis? Mass centers of gravity?
Ted
RE: moment of inertia
Certified SolidWorks Associate
SW2009 X64 SP 1.0
Dell Precision T5400
Nvidia Quadro FX 5600
Xeon 2.5GHz Quad Core, 4GB RAM
XP Pro X64 SP2.0
RE: moment of inertia
if the arm is rotated 90deg, the horizontal x-axis inertia Ix'x' is the original Iyy ... no ?
RE: moment of inertia
I don't know the formula to calculate the inertia.
Certified SolidWorks Associate
SW2009 X64 SP 1.0
Dell Precision T5400
Nvidia Quadro FX 5600
Xeon 2.5GHz Quad Core, 4GB RAM
XP Pro X64 SP2.0
RE: moment of inertia
Ixx = int(y^2dA) = sum(Io+y^2*A)
the 1st is mathematically correct, but not stunningly usefull.
the 2nd is for summing rectangles (or other convenient pieces of the section) ... Io is the self moment of the piece, A it's area, y it's distance for the NA.
RE: moment of inertia
Certified SolidWorks Associate
SW2009 X64 SP 1.0
Dell Precision T5400
Nvidia Quadro FX 5600
Xeon 2.5GHz Quad Core, 4GB RAM
XP Pro X64 SP2.0
RE: moment of inertia
RE: moment of inertia
The rigorous way is to use the Parallel Axis Theorem and sum the individual component inertias. I don't have my references handy, but I found this on the net that will do well enough:
http:/
In your situation,
Mi = mass of individual component
di = distance from individual component's centroid axis to the parallel axis
Ii = mass moment of inertia of individual components
Itotal = Σ( Ii + Mi*di^2)
Of course you could estimate the extrusions as simple blocks...the difference won't be that much, and will give you a conservative estimate. It simply turns into a tedious arithmetic excercise.
TygerDawg
Blue Technik LLC
Virtuoso Robotics Engineering
www.bluetechnik.com