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1500 questions
10
votes
7 answers
How to make factory machine hard disk drive more durable? How much its estimate life span?
I wonder how can I make hard disk drive more durable? Specifically, I works in a factory environment. And almost every few months, hard disk drive in some of the factory machine are corrupted, and even unrepairable. We already implement several SSD…
adadion
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10
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4 answers
Why does the stress-strain curve decrease?
This is a stress-strain diagram
I have noticed that the curve decreases between points C & D and between E & F.
Why does that happen? I expected the curve to always increase since the tension force in a tensile test is always increasing and the…
Eman.suradi
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10
votes
1 answer
Determining the difference between US Bailey Bridge, UK Bailey Bridge, Mabey Compact 100 and Acrow 300
Background
The Bailey Bridge panel bridge system has been around since WWII. It has been credited as being one of the top 3 technological advancements that allowed the allies to win the war. After the war, the surplus of Bailey Bridge parts were…
Forward Ed
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9
votes
1 answer
"u" vs "n" orientation of channel profiles: why difference in strength?
For example, metal tape measures can be extended and stay straight when in a "u" orientation, but collapse the other way round.
I presume the same phenomenon is why metal shelving has sheet metal on top, and flanges on the bottom rather than the…
Jodes
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9
votes
9 answers
Why aren't counterweights used more for garage doors?
One of my garage door torsion springs broke again. It makes me wonder why some sort of counterweight system isn't used instead. Torsion springs seem to have a 90 day warranty generally and are "rated" for up to 15,000 cycles. It seems like there…
Jason Goemaat
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9
votes
1 answer
Forcing a part into "home position"
I have a design with two parts (at the moment):
a fixed 10cm ring with vertical tracks
a freely rotating block with a cut that may freely slide along that tracks:
I'm trying to find a low profile way to ensure that whenever the cut in the moving…
John M.
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9
votes
5 answers
Difference in energy consumption between empty fridge and fridge filled with bottles of water
I have about 12 bottles of water. If I want to minimize the energy consumption of my refrigerator, should I put these bottles in the fridge or leave them out?
fronthem
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9
votes
1 answer
Why don't we use principal maximum stresses when designing a structural element?
Consider a concrete column is under compression from top loading and also carries some shear stresses.
If take a plane 2d element in the column with these stresses and rotate it to the point it gives out the it maximum normal stress then rotate it…
InstallGentoo
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9
votes
4 answers
Can cameras+display screens with window/mirror-like optical behaviour exist?
Display screens connected to cameras are significantly different from windows or mirrors. Looking through a window or mirror, we can focus on infinity, and we can move our vantage point to see a little different. With a display screen showing live…
gerrit
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9
votes
3 answers
Why don't we just build a giant wind turbine?
The power generated by a wind turbine is given by:
$$\mathrm{Power} = \frac{1}{2}C\rho AV^3$$
Where:
$\rho = \text{Air density}$
$C = \text{Coefficient of performance}$
$A = \text{Frontal area}$
$V = \text{Velocity of the wind}$
In other words,…
Chong Lip Phang
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9
votes
2 answers
What does "a" mean at the end of a refrigerant's designation (R-134a)?
I was studying the designation of names to refrigerants.
The following is the basic formula:
R - (m - 1) ( n + 1) ( o )
where:
m = number of carbon atoms in the refrigerant
n = number of hydrogen atoms in the refrigerant
o = number of fluorine…
Fennekin
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9
votes
1 answer
Derivation of the weak form for the euler-bernoulli beam equations
I am master student and doing an assignment of Finite element method. In the instruction I could not understand the derivation of the weak form, which should not be difficult. I'm sorry for posting this easy and most likely not helpful question for…
user26767
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9
votes
2 answers
What is the maximum length of oil pipelines?
This is inspired by the discussion and controversy surrounding the Keystone Pipeline.
The main part of the Keystone Pipeline system is about 3,400 kilometers long, stretching across a large portion of the United States. The Keystone XL extension…
HDE 226868
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9
votes
2 answers
Material selection for weight scale
I am looking to test the FlexiForce sensor in measure force, however for accurate readings the load needs to be disturbed evenly over the sensing area. As such I am having "discs" made to cover the sensing area. For my application the thinner the…
Anthony Phan
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9
votes
3 answers
How can the wobble of a rotating cantilever shaft be reduced?
I have a cantilever shaft 6inches in length supported on one end using a ball bearing. I am having problems of shaft wobbling in the bearing. I cannot have support on the other end.
How can I help this situation?
The shaft is made of aluminum,…
Hardik shah
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