Urethane, 90 Duro strain energy
Hey guys,
I need to know how much strain energy a rectangular piece of urethane has when compressed... For discussion purposes, say I have a 150mm x 200mm x 25thk block of 90 durometer urethane and I compress it 2.5m... How much force will this take? I've never calculated with Urethane before
Thanks
Plastic Part Carrying Torque and Radial Load
Hi Folks,
I'm at it again. I'm working on a plastic "carrier" component to transmit power from an output shaft. I wanted to use a round shaft with two opposed flat sides to do this. I've tested some 3D printed parts and it transmits the torque fine. My problem is that this part is always under a radial load. When I test this the shaft eats up the inside diameter. I've got about 70W at 200rpm with 200N radial force on a ΓΈ10mm shaft.
I've designed a similar plastic carrier in which two mini ball-bearings were pressed and the part was placed on a stationary shaft. This time the torque was transmitted via an additional geometry on the part. But the bearings were carrying the same radial load. At the end of the lifetime the bearings no longer have a press fit, but this has not been any real problem.
One problem I have is that the prototype material is PA12 and the final material will be POM acetal resin. So the properies are significantly different. I'm working on doing a realistic test, but I'm wondering if there are fundamentally better options such as a cross-bore and pin instead of the two flat sides. We have sintered steel carriers which mate to the same shaft using a woodruff key and the key is pretty worn at the end of expected lifetime. Trying to go to plastic due to more complex shapes for functionality.
Any tips are greatly appreciated.
gear design software
hello is there any software which will calculate how to manufacture gears ? with correction factor, pitch, centres etc
I have a gear train with 4 gears located. but 3 of the gears will hae different teeth counts and will be interchangeable.
i.e first gear = 17,18,19 teeth. 2nd gear 58t, 59t 60t.
each gear there needs to be interchangeable.
any help would be appreciated.
I need to lift a roof
I have a outdoor structure that I'm replacing the entire roof on but it's 20' in the air. And when I say "the entire roof" I mean everything from the trusses to roof metal. Because of the structure design I built the roof on the ground with the intent of hoisting the old roof off and hoisting the new one on but my fairly simple plan has been overcome by design changes ("sure hon, I can make that look like you want.") So now I think my only option is to place two beams under the frame, attach my hoist cables to the ends of the beam and hoist away. I'm hoping someone can tell me the least expensive thing to use as my lift-beams.
The structure base is 10'x10' made from 4-4x6 treated yellow pine. The total weight of this roof is about 2700 pounds. My rafters extend about 2' below the base and 3' beyond so the outer dimensions are 16' x 16'. My thinking is to use two engineered wood beams/pipes/square tubing/dimensional lumber (this is where I need your help) to place parallel under the structure, use 4x6 scraps as spacers under the base to keep the YTBD beam off my rafter tails and attach my straps to the ends and hoist away. I can add spacers above if I need to but I don't know what to use under the roof structure to lift it. I also have to be able to be able to manhandle the YTBD 20' long "beam" once the roof is in place since I can't just drop it to the ground, though I can take it apart if I need to.
I've looked at the engineer calculators and figured all the loads but that just gives me a bunch of numbers that don't tell me what to use so I'm hoping someone on here can give me that answer. Bubba up the street has provided his input but I think I'll ask an engineer. I can upload pics if it'll help.
Grit removal channel design for industrial drainage (not waste water treatment)
Hi all - I am investigating grit removal options for removing mostly sand from water draining from industrial washing machinery, but need advice specifically regarding grit removal channels used in smaller scale applications.
Most of the guidelines readily available online pertain to the design of grit removal chambers for large waste water treatment plants, where flow rates of the order of Mega Liters per day are anticipated, compared to the flow rates of approximately 10 l/s in a discharge time of 900 s, once a day, with each discharge containing up to 20 kilograms of sand, specific to the application I am investigating.
I have considered applying the principles of dimensional analysis to the equations and constants used in the design of channels (longitudinal, or aerated) for larger applications, but am not satisfied with only this approach. It would probably be a good time now to mention that mechanically driven machinery would require too much maintenance and will not be considered, and that I am only considering the aerated type of chamber because air compressors will be readily available on site.
Can any of you recommend literature, or rules-of-thumb based on experience, about the design of grit separation chambers for smaller drainage applications?
Usage of one way bearing
I am developing a motorized cable reel. I am using a geared DC motor to drive central cable drum on which the cable rests. This cable reel is only used to automatically retract the cable back once the cable is pulled out. The cable is pulled out manually by hand from the cable reel.
I am using a one way bearing coupled to my DC motor shaft to make it easy to pull out the cable manually. The one way bearing housing is in turn connected to a small sprocket. The small sprocket is connected to the bigger sprocket (attached to the cable drum) via a chain.
Now, the problem that I am facing is that the whenever I power on the motor, the entire assembly rotates in the direction that the one way bearing moves. But what I need is the assembly needs to rotate in the direction opposite to which the bearing moves. On the side where the bearing rotates freely , I pull the cable out manually (as the bearing makes it easy to pull cable out), and I dont turn on the motor in this case. In the other direction where the bearing doesn't move, I need the entire assembly to rotate in order to pull the cable in, but what happens is that just the motor shaft rotates, the bearing, bearing housing, sprocket, etc dont move.
What modifications should I make to achieve my goal or any other alternatives for this ? I cannot use an electromagnetic clutch here.
Also, below is the link to a video where I explain the problem I am facing. problem explanation video
Also, the one way bearing is connected to the motor shaft via a keyway slot on the bearing and a key on the shaft. I am trying to use the same cycle chain and sprocket concept here and I am trying to understand where I am going wrong here.
calculation of water flow rate in heat exchanger (water-air type)
Frankly speaking, I am not an engineer. But I know little bit physics.
To lift 250 watts of heat from my system, I want to use a water-air heat exchanger;
i.e. water will take out the heat from metal block (which is hot) and will give out that heat
to ambient (through fan). In this process, water will become hot and then cold. So there will
be one inlet & one outlet in the heat exchanger. Water will thus be circulated in closed loop.
Metal block can be inside a vacuum chamber.
I want to calculate water flow rate for this.
I am using following equation :
q = D*F*c*(T_out - T_in),
where q = heat to be removed
D = density of water
F = water flow rate (liters/minute)
c = specific heat of water
T_out = temp. of water coming out of heat exchanger
T_in = temp. of water going into the heat exchanger
I want to keep the metal block at 30 deg C. Also ambient temperature is 22 deg C.
In above equation, I do not know what value I should put for T_in & T_out.
Also, this equation does not contain surface area of contact between metal block & water.
Does this surface area matter in calculation of flow rate ?
Any help will be highly appreciated.
Pulleys : How to get to MA 14:1 with as few pulleys as possible .
Hi all,
Im a Noob , and I need the help of the community to help me solve some of the issues I've been having with this recreational project I've been putting together.
As the title suggests, Im trying to construct a setup to attain a 14:1 Mechanical Advantage with as few pulleys as possible. Im trying to move my load 5 inches
Ive seen some concepts of compound and complex pulleys, but I cant quite wrap my mind around the setup .
This is my very first post on this forum ,so forgive me if I lack the etiquette the community expects.
Thanks and hope to hear from you all soon ,
Pumping against Vacuum
I have a vacuum vessel that is half full of water and -0.7 bar vacuum maintained above it. I am constantly filling the vessel with cold water and removing it with a centrifugal pump. The tank outlet is on the bottom that runs down about 3 feet to the inlet of the pump. There is a small line (1/2" or so) that connects the top of the vessel to the pump discharge, balancing the pressure across the pump. My question is what pressure should I see at the pump inlet with -0.7 bar vaccum in the tank above and the pump not running? Should I still see 36 inches of water pressure, or does the vacuum have an effect? Also, when the pump is running, should I still see pressure there (maintain NPSH on the pump)?
Yield strength of a gusseted joint
I am building some steel tube structures and it is clear that one of the joints needs a gusset. This will lap over the tube effectively increasing the wall thickness in an area, rather creating any sort of extra triangulation. When thinking about the additional strength that the gusset will add to that location, is this basically an additive process where a gusset of X cross section and Y yield strength with increase the yield strength of the new joint by X*Y?
Basically, I am considering using material for the gusset which has a lower yield strength than the main structure's material, and am wondering if this is actually more of a complicated interaction than it seems.
Thanks in advance for the advice and insight!