Simple static problem
Simple static problem
(OP)
Hello All,
I am having problem in solving a very simple static problem. I need to find the resultant load and its location. See the attached snapshot of the problem description.
Thank you
I am having problem in solving a very simple static problem. I need to find the resultant load and its location. See the attached snapshot of the problem description.
Thank you





RE: Simple static problem
Quando Omni Flunkus Moritati
RE: Simple static problem
I am reading information on force polygons based on your comments.
RE: Simple static problem
the question is asking what are the co-ordinates of the load, so that the three force directions (AP, BP, CP) resolve the applied load. this is going to be easier to solve through "equations of equibilirium" ... summing the force components so that sum Fx = P and sum Fy = 0. force components depend on their angles determined by x and y. the "lazy" way to solve is to up a spreadsheet with x and y as input, ie guess these, that'll determine the lines of action of the three reactions, and so their components in the x and y directions and so check against the required summs, and change your guesses.
Quando Omni Flunkus Moritati
RE: Simple static problem
that said there should be a line of solutions (since there are two variables and one equation)
Quando Omni Flunkus Moritati
RE: Simple static problem
so for i get sumFy = 0,
-1006.1*(y/x)+3416.1*(y/(21-x)-1150*((16.3-y)/(21-x)) = 0
(sum Fx already balances, sumM balances as all forces go through a common point)
to solve the redundancy assume all three are the same area, so sum forces is a measure of strain energy; and pick (x,y) that minimise this sum.
my answer, x=8.7325
you can check by drawing a force polygon of the three reactions, and see that the applied load closes the polygon.
Quando Omni Flunkus Moritati
RE: Simple static problem
X can be anything.
RE: Simple static problem
Quando Omni Flunkus Moritati
RE: Simple static problem
RE: Simple static problem
Even i came up with the same answer. But what threw me off here is, X can be anywhere.
Check the picture attached.
I started thinking that 5572.1 lbs applied at one end (D) at a 3.36 inch distance will load differently than at D' or at D".
RE: Simple static problem
RE: Simple static problem
RE: Simple static problem
if the reactions at A, B and C are horizontal, and the load is horizontal then your solution is correct. A, B and C are all roller reactions, with no y-component.
put a big solid rectangle between A, B and C (instead of three lines) and apply to force. C reacts the overturning moment.
i guess "x" is a trick part of the problem.
btw, review rules on student posts.
Quando Omni Flunkus Moritati
RE: Simple static problem
RE: Simple static problem
A resultant load dimension (X Y) is what i need to find and apply. The fixture can be a co-linear square tube transferring load to three end points.
(By the way, I am a professional who needs to go back to school for basic statics
RE: Simple static problem
They can't all be rollers, as that would make the assembly unstable. With axial inclined members, if there is a horizontal component, there has to be a vertical component. Even with your "big solid" block, which makes the assembly a moment resisting frame, at least one of the supports has to be a pin to assure stability.
RE: Simple static problem
RE: Simple static problem
RE: Simple static problem
but if your structure is more linear (like the three dotted lines), then you have a simpler problem (you know the line of action of the reactions) and can solve the single redundancy that can be solved along the lines i've posted (but i suspect that you haven't understood them).
this has become an extremely frustrating thread ... a badly phrased question, and now with missing key info ...
Quando Omni Flunkus Moritati
RE: Simple static problem
RE: Simple static problem
https://www.youtube.com/watch?v=TlznZHClMLY
Sorry for adding this after you proposed to close the thread :)
"If you want to acquire a knowledge or skill, read a book and practice the skill".
RE: Simple static problem
https://www.youtube.com/watch?v=R5p5J-O_iFA
"If you want to acquire a knowledge or skill, read a book and practice the skill".