All Questions
34
questions
1
vote
0
answers
18
views
What is the Hoop stress and bending moment relation
So I am working on a club telescope project. I have to design the tube for the telescope.
So I found hoop stress to be most critical stress.
The tube's bottommost end has a mirror and a mirror cell. I ...
0
votes
0
answers
20
views
Determine moment and shear stress door
Determine shear stress and moment of bolt:
Internal Height of Door = 198.2 cm
Internal Width of Door = 89.9 cm
Thickness Door = 3.9 cm
Weight Door = 45.76 kg or448.9 N
Elasticity = 9.8 GPa or N/mm2
...
- 1
-1
votes
3
answers
60
views
Why are the water tank walls made of stretch film warping a lot whereas theoretically they shouldn't that much?
I am building a water tank of custom dimensions (1.5 m x 0.72 m x 0.86 m) out of stretch film. The stretch film is wrapped around a steel frame (see here for more info on this open source project).
I ...
- 101
-1
votes
2
answers
62
views
What does cycle mean in fatigue strength diagram?
A shaft at an usual factory might rotate 2000-3000 (10^3-10^4) per day. So, its rotation cycle easily reaches numbers indicated on X axis below. What does number of cycles in the diagram below exactly ...
- 125
0
votes
3
answers
92
views
Resultant Forces in a vertical rod
This is a pretty basic question. So in the below figure is the representation of prismatic column. The forces are represented as P1 and P2. let x be an arbitrary cross section between A and B. The ...
1
vote
0
answers
41
views
Why are these food stretch films (LLDPE) holding one one-thousandth of the weight in reality than what is expected from the datasheet values?
I am trying to reproduce analytically the results found in this experiment where a weight of 3 x 5 lbs (6,8 kgs total) breaks the cling wrap (LLDPE) which is stretched over a medium size cooking pot.
...
- 111
0
votes
1
answer
53
views
The hanging of lead weights in the Cavendish experiment of 1798
I'm working to build the Cavendish experiment of 1798 according to Cavendish's own specifications. I have a question about the hanging of the 150 kg lead weights.
As seen in the image, there is a ...
- 101
0
votes
1
answer
1k
views
What are the physics behind a TV wall mount?
As I was installing this wall mount, I began to wonder how exactly physics is at work with it. In other words, how does the design of the mount play a role in ensuring that the mount itself supports ...
- 121
0
votes
1
answer
104
views
Stress on a statically indeterminate beam with nonuniform temperature distribution
The bar below has length $a$, an uniform cross-section and has both ends fixed to walls. The temperature at the left end is raised by $\Delta T_1$ and that of the right by $\Delta T_2$, where $\Delta ...
- 15
0
votes
1
answer
1k
views
Choosing metal plate to spread point load
I have a heavy object standing on 4 legs (about 30 mm in diameter each) on a wooden floor. The object is soon going to become even more heavier and I am concerned the legs could penetrate the floor. ...
- 211
0
votes
2
answers
344
views
Stress-strain Curve Interpretation
A significant barrier to my understanding of typical engineering stress vs. engineering strain curves is that for certain values of stress, there are multiple values of strain (i.e., the stress-strain ...
1
vote
3
answers
1k
views
Failure load of hollow tube under transverse compression
How would one analytically calculate the maximum force a tube under transverse compression can withstand? I am specifically looking for a general equation to model the yield strength of a hollow tube ...
0
votes
1
answer
205
views
Why von-mises criteria considers the second invariant of deviatoric stress? [closed]
Why only the second invariant is considered? What about the third invariant?
- 1
0
votes
4
answers
359
views
When we replace supports distributed reaction by point reaction in thin beams, is that considered an application of Saint-Venant principle?
I read about Saint-Venant principle which is about the effect of replacing forces by equivalent forces system that effect on the same small region of a rigid body, all examples I come across are on ...
1
vote
4
answers
103
views
Mechanics: example of less mass/volume gives more strength
Lets assume we have a mechanical element from uniform material that is supposed to work in a static load conditions. Moreover lets assume there is no gravity or gravity is negligible.
Are there any ...
- 61