Simple static load problem giving me hell (sketch provided)

  • Thread starter Thread starter FreeBodyDiag
  • Start date Start date
  • Tags Tags
    Load Static
Click For Summary
SUMMARY

The discussion centers on a design evaluation problem involving static load analysis using WorkingModel software. The user is attempting to calculate reaction forces at fixed pins 11 and 3, as well as the force at pin 13, under a 10kgF downward load. The software's output for forces (Fx, Fy) does not satisfy the equilibrium equations, specifically the sum of forces in the X direction, leading the user to question the validity of the software's calculations.

PREREQUISITES
  • Understanding of static equilibrium principles
  • Familiarity with WorkingModel software
  • Knowledge of reaction forces in structural analysis
  • Basic trigonometry for resolving forces
NEXT STEPS
  • Review static equilibrium equations in structural mechanics
  • Learn how to validate software outputs against hand calculations
  • Explore advanced features of WorkingModel for load analysis
  • Investigate common pitfalls in static load problems
USEFUL FOR

Engineers, students in structural analysis, and professionals using simulation software for load calculations will benefit from this discussion.

FreeBodyDiag
Messages
11
Reaction score
0

Homework Statement



This is not actually a homework problem but a design evaluation problem I have encountered.
I am trying to solve for all the loads at the pins and have used WorkingModel to try and give me some quick answers. However, the solutions offered by the software do not make sense to me/can't verify with hand calcs.

The image below shows the values of Fx, Fy and F as calculated by the software at each pin. I have added the co-ordinates of where the pin joints are and where the load acts (in mm). +X is to the right, +Y is to up. The load acting on this system is a 10kgF acting directly down as shown. Each grid square is 50mm wide. The mass of the elements is set to zero.

[PLAIN]http://img833.imageshack.us/img833/7528/forces.jpg

The unknowns are the reaction forces (Fx, Fy) at each of fixed pins 11 and 3 and the force acting on the pin at 13.

Homework Equations



Ʃ forces in X direction = 0
Ʃ forces in Y direction = 0
Ʃ moments about any point = 0
M=F.x
cos(θ)=A/H
sin(theta)=O/H
tan(θ)=O/A

The Attempt at a Solution



Unless I have severely overlooked something, I immediately dismiss the solutions offered by the software because a simple check of the equation:

Ʃ forces in X direction = 0
...reveals that this is NOT the case.

Ʃ forces in X direction = Fx@pin11 + Fx@pin3 + Fx@LOAD
= (-5.186) + (16.305) + (0)
≠ 0!

??

What is going on here? Am i going loco or is this solution just plain out wrong?

Thanks
 
Last edited by a moderator:
Physics news on Phys.org
(hand calc removed because of error)
 
Last edited:

Similar threads

  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 2 ·
Replies
2
Views
4K
Replies
3
Views
3K
  • · Replies 5 ·
Replies
5
Views
5K
  • · Replies 9 ·
Replies
9
Views
15K
  • · Replies 6 ·
Replies
6
Views
3K
  • · Replies 1 ·
Replies
1
Views
4K
Replies
3
Views
2K
  • · Replies 4 ·
Replies
4
Views
4K
Replies
2
Views
4K