arokisbobcat
- 11
- 1
- Homework Statement
- Find the internal moments on the stretchers of the chair.
- Relevant Equations
- Sum of Moments = 0. Forces X and Y sum to zero.
In the attached document, I am attempting the problem that they go through in Figure 4-25, Force Equilibrium in side frames. A chair with 3 stretchers is considered as having a 200 lbf. person sitting on it and a 100 lbf. applied to the top edge of the chair creating an overturning moment. I am attempting this problem from some furniture design literature from Purdue engineering. I am having a couple of questions and am seeking some help.
Here is my first question. If the 'seat load' force is 200 lbf, then wouldn't the reactions be 100 lbf. on the front leg (downward) and 300 lbf. on the rear leg (upward)? Please see my attachment labeled 'Furniture Reactions'.
My second question is how the author arrives at the internal moments on each of the 3 stretchers from top to bottom of 544 / 571 in-lb, 526 / 525 in-lb, and 513 / 521 in-lb. In my attachment labeled 'Problem', I cut the member at the front leg and take moments about each of the stretchers. Unfortunately, they equal out and I can not see how they author is getting these internal moment values stated above.
Attached are my attempts and also the literature of the stated problem in Figure 4-25 beginning on page 4-20 in the Furniture Analysis attachment. Any help would be appreciated to help me see what I am missing.
Here is my first question. If the 'seat load' force is 200 lbf, then wouldn't the reactions be 100 lbf. on the front leg (downward) and 300 lbf. on the rear leg (upward)? Please see my attachment labeled 'Furniture Reactions'.
My second question is how the author arrives at the internal moments on each of the 3 stretchers from top to bottom of 544 / 571 in-lb, 526 / 525 in-lb, and 513 / 521 in-lb. In my attachment labeled 'Problem', I cut the member at the front leg and take moments about each of the stretchers. Unfortunately, they equal out and I can not see how they author is getting these internal moment values stated above.
Attached are my attempts and also the literature of the stated problem in Figure 4-25 beginning on page 4-20 in the Furniture Analysis attachment. Any help would be appreciated to help me see what I am missing.