Stress analysis on spars for an airfoil

  • Thread starter wahaj
  • Start date
  • #1
156
2

Homework Statement


If I have two spars running through an airfoil, which can be assumed to be two dimensional, which method would I use to find the stresses at the points where the spars are fixed? The loads would be lift and drag and what I need are the bending and shear stresses. Because I have more than one spar, I am looking at a statically indeterminate problem.
Another question, my professor said that to simplify the problem, I can apply the lift and drag forces at the quarter chord point. Would these forces act on the mean camber line or at the upper or lower surfaces?

Homework Equations




The Attempt at a Solution


I don't think I've been taught how to do this yet. I am willing to read ahead but I don't know what I should be reading. I have access to the Beer and Johnston Mechanics of Materials textbook
 

Attachments

Answers and Replies

  • #2
18,363
8,215
Thanks for the post! This is an automated courtesy bump. Sorry you aren't generating responses at the moment. Do you have any further information, come to any new conclusions or is it possible to reword the post?
 
  • #3
CWatters
Science Advisor
Homework Helper
Gold Member
10,532
2,298
I would assume that the drag force acts on the centre line of the spars so that it doesn't cause any twisting of the wing (and to make the problem easier :) )

Aside: Real wings have a "pitching moment" that tends to twist the wing nose downwards. It's why the tail on most aircraft is set at a negative angle of attack.

my professor said that to simplify the problem, I can apply the lift and drag forces at the quarter chord point
That should allow you to work out how the lift force is shared between the two spars.

I'm not a mech. eng. so not sure how you work out the rest.
 

Related Threads on Stress analysis on spars for an airfoil

Replies
3
Views
2K
  • Last Post
Replies
14
Views
4K
  • Last Post
Replies
1
Views
2K
  • Last Post
Replies
16
Views
3K
  • Last Post
Replies
22
Views
3K
  • Last Post
Replies
8
Views
2K
  • Last Post
Replies
1
Views
989
  • Last Post
Replies
1
Views
1K
  • Last Post
Replies
1
Views
7K
Replies
0
Views
5K
Top