Shear Force
Shear Force
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Im looking for the shear force on any given object at 4' depth on the inside wall of a hopper of cement (density=90lb/ft3)? This seams like a dam problem??
Im looking for the shear force on any given object at 4' depth on the inside wall of a hopper of cement (density=90lb/ft3)? This seams like a dam problem??





RE: Shear Force
I don't think there is a shear force.
Cheers
Greg Locock
SIG:Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips.
RE: Shear Force
RE: Shear Force
RE: Shear Force
Solid material and bins and liquids in tanks behave differently.
RE: Shear Force
Yes, but I said "fluid", not liquid...but you're right, the equation would not be valid for dry powder.
RE: Shear Force
The cement is not flowing , now.
And if dry power was flowing, just subsitute density values!
I have the engineer hat on now (there goes some variables)
At 90lb/ft3 and at 4', it would be a rough 360lb/ft3.
Now just a down force would be 360lb on a "surface"area of 1 sq ft., right?
If any object of say 1"x1"1" is present, them just convert from ft to in??
RE: Shear Force
RE: Shear Force
cheers,
RE: Shear Force
Cheers
Greg Locock
SIG:Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips.
RE: Shear Force
Btrueblood, is your equation good if there is a flow, 5cuyd/hr.??
RE: Shear Force
Static, no motion.
P = (rho)x(g)x(h)
P = (p)x(g)x(h)
P = (90lb/ft3)x(32ft/sec)x(4ft)
P = 11,520lb of force on a object at 4' deep ??
If, and if this is right would it also be the shearing force equlivent on an object at that depth??
RE: Shear Force
For dry powder, the problem gets stickier (pun intended), as Mint suggests. The powder can stick and clump, and even when dry it has an angle of repose...so voids may form below protrusions as the powder fills the hopper. Worst case is the full hydrostatic pressure of the fluid on one (typically the top) side of a protrusion, and zero pressure (void space) beneath. I think.
RE: Shear Force
Fe
RE: Shear Force
that is not a shearing force on an object under hydrostatic pressure.
Pressure_hydrostatic=rho*g*h (N/m^2 or lb/ft^2)
(as stated by the others)
Fe
RE: Shear Force
I did not look closely at your equations before. Even if you had a fluid, which you don't, the fluid equation gives a pressure
P = rho*g*h
So, you have P = (1440 kg/m3)*9.81 m/s2* 1.2 m = 17.2 kPa
Which you can convert back to psi at your leisure. There's a lesson to learn here: always convert to SI units when doing physics. Life is just easier that way.
To find the force acting on an object at that depth, you need to know the projected area of the object...
P*A = F (again, use the SI units and convert the force when you are done).
RE: Shear Force
http://
is at least a step forward
Cheers
Greg Locock
SIG:Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips.
RE: Shear Force
If the flow is not falling on the object, and given the bin's size and that the cement is aerated, the forces would be only based on buoyancy, as they would be if you slowly filled the bin with water.
When the bin empties, you may get some build-up on the top of the sensor which you would need to account for.
Either way, a 2" diameter piece of pipe, 2' to 3' long should have no problems if properly secured at the fixed end.
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RE: Shear Force
This sensor could be a paddle wheel type and need shearing forces on it, to see if it will not snap off.
Here is bin design, sensor or object is at 4ft depth. say that the object is 3"X2"X1".
what would be shear forces on it?
RE: Shear Force
If you are involved in handling and storage of bulk solids check out these specialist forums :-
http://www.bulk-online.com/Forum/index.php