Tek-Tips is the largest IT community on the Internet today!

Members share and learn making Tek-Tips Forums the best source of peer-reviewed technical information on the Internet!

Register Log in
  • Congratulations cowski on being selected by the Eng-Tips community for having the most helpful posts in the forums last week. Way to Go!

Moment of Inertia

Status
Not open for further replies.
Rodrigo Pena

Rodrigo Pena

Aerospace
Joined
Jun 10, 2022
Messages
4
Location
CA
Hello all, hope you are doing great.


I am building an spreadsheet to calculate the reactions on 3D bolt group and I would like to confirm an information.

Screenshot_q09umb.png


I calculated the moment of inertia about the centroid of my bolts in all 3 planes, my question is:

Can I add Ixx from xy plane and Ixx from xz plane ? I have to come up with only 1 Ixx to calculate the constants.

Thanks !

 
Sort by date Sort by votes
not really sure what calc you're doing ... can you show the geometry ?

I'm not sure how you get two inertia terms for all three axes ? I'd've thought that there be only one term ... unless the plane of the fasteners is generally inclined (but then you'd transform loads into this plane ... won't you ?).

another day in paradise, or is paradise one day closer ?
 
Upvote 0 Downvote
The geometry is a circle, the diameter of the bolt is 0.18 in^2.

my spreadsheet is enclosed. go to 3D bolt group and formulas and calcs tab
 
Upvote 0 Downvote
your attachment is a screen shot.

If you have a bunch of bolts on a PCD, then you have Ixx = sum(A*y^2) = Iyy. You could calc Izz, but I'm not sure why you would (but in any case = 2*Ixx).

another day in paradise, or is paradise one day closer ?
 
Upvote 0 Downvote
yes, now you've linked your s/sht.

I don't know I'd consider the Z (= 4) term and calc Ixz and Iyz.

You seem to be doing a lot with this. I don't think I've ever seen people include the local I of the bolt (and just use Ay^2).

another day in paradise, or is paradise one day closer ?
 
Upvote 0 Downvote
I see... I got some results that matches with other spreadsheets.

Thanks !
 
Upvote 0 Downvote
Status
Not open for further replies.

Similar threads

MCA1983
  • Locked
  • Question Question
Moment of inertia (MOI) - Area moment of inertia
Replies
5
Views
700
sdm919
sdm919
oriolbetriu
  • Locked
  • Question Question
Learning how to calculate secondary moment using Bruhn's
Replies
9
Views
9K
LiftDivergence
LiftDivergence
G
  • Question Question
Looking for the AMS equivalent of ASTM B221 (6061-T6)
Replies
7
Views
6K
Sparweb
Sparweb
M
  • Question Question
how to calculate drag and lift coefficient at different airfoils of horizontal axis wind turbine blade
Replies
4
Views
6K
LiftDivergence
LiftDivergence
MCA1983
  • Locked
  • Question Question
Rivet Size & No of Rivets vs current (Amperes) Requirement
Replies
6
Views
3K
rb1957
rb1957

Part and Inventory Search

Sponsor

Back
Top