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Questions tagged [friction]

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0
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2answers
58 views

Dead mans brake on a hand-pushed wheelchair

Would it be possible to install a dead-mans brake on a wheelchair? I have been calling around and wheelchairs do not seem to come with a dead-mans brake. With that i mean the brake found on airport ...
1
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1answer
31 views

Pacejka “Magic Formula” tire models origin of the name

It might be a little off topic but I'm trying to find source for why is that model called magic formula? I read that it's a simple function of commonplace functions, a data fitting. Is it simply an ...
0
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2answers
72 views

Refute my assumption: Bearings Don't Improve Efficiency

If two surfaces rub together with a normal force between them, friction is generated. You could add lubrication between those two surfaces and reduce that friction. Bearings essentially consist of ...
1
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2answers
37 views

How to keep lighting “barn doors” open

I have two alum plates (45cm x 20cm x 1mm) that are hinged on the long side with two 30 x 80 hinges (30 x 40 each tang) in the middle, and "L" bracket / 20mm brace at the ends secured with a M4 loc ...
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1answer
38 views

What are fluids or “goos” called, that increase friction?

I have a shaft inside a bushing, the shaft has a gear on one end that is supposed to provide resistance to other gears it is driven with. I'm having a hard time finding the correct term for the sort ...
1
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2answers
59 views

Which design to maximize friction for a device standing on concrete?

I have a device 4cm X 5cm X 15cm that stands on asphalt/concrete/road. So, the device is taller than its base which makes contact with the asphalt. I want to maximize the friction so that the device ...
1
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1answer
20 views

Effect of friction (or horizontal motion) on vertical surface deformation

I am trying to model the dynamics of some system. In summary, the system consists of one horizontal linear actuator that drives an object along a planar surface and one vertical actuator that brings ...
0
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1answer
33 views

How do you calculate the chain tension required when compressing bulk material over a conveyor?

Bulk material is conveyed over a slat conveyor, and the material is leveled with overhead rollers while being transported in the conveyor to maintain an even material height. Most of these "levelers" ...
0
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1answer
43 views

Minimum required rolling friction between pulley and the rope

The 40 kg weight accelerates and runs on a rope from 0 to 50 km/h in 10 seconds. I want to calculate the minimum required rolling friction that I need (acceleration without slipping) to achieve ...
1
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0answers
15 views

Regarding the ITTC Guidelines for Ship CFD applications

I was reading through the ITTC – Recommended Procedures and Guidelines - Practical Guidelines for Ship CFD Applications (https://ittc.info/media/4196/75-03-02-03.pdf) document and this little thing ...
2
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1answer
65 views

Material with strongest grip on Aluminium 6061

Attached is an example picture of a clamp that will be attached to a pipe made of Aluminium 6061-T4. The clamp should have very tight grip on the pipe and prevent it from slipping or rotating but the ...
1
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0answers
83 views

statics exam question about friction

In a statics exam I had the question in the picture attacehd and I had some trouble understanding it. The question is so Under the effect of torque Mo rotates a wheel (radius r) with constant ...
3
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1answer
61 views

Ideal funnel design for powders

I'm designing a funnel/bottle for a powder. My goal is to have all of the bottle's powder contents come out when inverted. However, the powder has a tendency to stick to itself (like flour or brown ...
1
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0answers
33 views

Why increasing the coefficient of friction results in evenly distributed load in rolling machines?

I'm designing a rolling machine for reduction of steel ingots of $5 mm$ to $1.96 mm$ thick. I can convince myself using equations why increasing the coefficient of friction (in case of lubrication ...
0
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1answer
516 views

How to find required clamping force of bolts to prevent flange faces from twising due to torque?

I have a gearbox adapter that bolts onto a flange and I need to work out how much clamping force is needed to prevent the faces from slipping and keep the bolts in tension rather than shear when ...
1
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2answers
63 views

Does a washer really increase static friction force?

Suppose I have a bolt that goes through a hole in a plate and is under tension. If I place a washer between the bolt head and the plate, does static frictional force (torque actually) really double? I'...
2
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2answers
130 views

Materials to use for a low friction cable-pull

I'm posting this question on this stack-exchange site, because it appeared to be the one made for this kind of questions. If this happens to not be the case, I'm sorry, I didn't know better. Also ...
1
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0answers
233 views

How Can You Calculate Force to Overcome Friction From an O-Ring Seal?

I essentially have a piston in a tube that is sealed with an O-Ring and actuated with a solenoid. The friction of the O-Ring however, is higher than estimated (guessed as far as I can tell) by the ...
0
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1answer
107 views

Pan and tilt mechanism

this is my first project that i am working on. I want to make a IR sensor mount using stepper motors. I seen this on youtube and would like to make a similar design. I plan on using aluminium ...
1
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0answers
37 views

How to make machined plastic part slippery for small dry particles

We have a plastic part that is a receptacle for small ( < 1mm ) particles. It is a disk with a shallow cone shaped indent made using a drill. When a particle is placed in the receptacle it should ...
2
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2answers
126 views

Mechanical device that creates friction when rotating?

I am designing a mock-up aircraft throttle, like one of these: In an airplane, it it slides forward and backward to control the thrust of the engines. The problem is, I am not sure how to go about ...
1
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2answers
150 views

Multilayered Bearing Spinner

I have a few questions relating to a multiple layered spinner that uses ball bearings to reduce friction, kind of similar to a fidget spinner. The image below is an example of the multilayered bearing ...
4
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1answer
188 views

Deriving the amplitude of a coulomb (dry friction) damped spring

This is my first time posting anything, but I could not figure out the derivation of the amplitude of the spring for the 4 first oscillations. I am not acquainted with the effect and calculations of ...
2
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3answers
97 views

Building a machine from an ideal physics problem

I have a physics professor for whom I'd like to build a machine. Featured in a problem he is notorious for assigning students, originally from Kleppner and Kolenkow's "Mechanics," the machine causes ...
3
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0answers
72 views

Torque needed to keep a wheel spinning at high RPM

I have a treaded wheel which is 16'' diameter and 4'' across (trailer wheel). If I want it to spin constantly at 2750 RPM, what amount of torque do I need to apply to combat friction and air ...
2
votes
1answer
258 views

Does oil actually “attract” dirt?

The conventional wisdom consistently holds that "oil (or grease) attracts dirt", giving rise to the need for seals and dry-lubricants. But I've always considered that to be loose thinking, the truth ...
0
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4answers
630 views

Brake pad materials for use against an aluminium surface [closed]

For a project that I am a part of, we are in need of a brake pad material for use against an aluminum surface without causing any damage to it. So far through my research, the only safe alternative ...
4
votes
1answer
54 views

Dimension of the unidirectional mechanical clutch

This is a problem from the book Engineering Mechanics Statics vol-1 by Meriam Kraige. The elements of a unidirectional mechanical clutch are shown in the figure.A torque $M$ applied to the outer ring ...
3
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1answer
65 views

Normal force between two boards

This is a problem from the book Engineering Mechanics Statics vol-1 by Meriam Kraige The rectangular steel yoke is used to prevent slippage between the two boards under tensile loads $P$ .If the ...
1
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1answer
42 views

Can the hysteresis phenomenon be considered as a (type of) friction

I was wondering whether the hysteresis (in particular, mechanical motion systems) can be considered under the class of friction. From theory, I know that the frictional forces are direction, and ...
1
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0answers
57 views

Spinning a balanced load with DC motor

Enclosed within a consumer electronic, I would like to spin a small balanced load. The device will be rotated relative to gravity, but no other direct forces will be applied to the load. A coreless ...
5
votes
1answer
521 views

Is a gear usually held on a shaft friction or an adhesive?

So, where I work, we have this arcade game, which is a classic claw machine. IN order to raise the claw up and down the machine makes use of a worm gear, like so: (although for the meticulously ...
2
votes
2answers
823 views

Good material for friction disk for a torque hinge?

What kind of material(s) would make a good friction disk, or disks, for a friction hinge, or torque hinge? This will be for the hinge on an arm that needs to be adjustable and also hold it's position ...
3
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1answer
100 views

Recreating Focaults Pendulum

I am having issues building a recreation of Focaults Pendulum (basic, inexpensive, undergrad project). At this point, I am going to purchase aircraft cable or suspension cable unless someone can ...
0
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3answers
528 views

Applications with combination of high friction and low wear?

What would be some common applications involving high friction and low wear rates? for example, gear-driven mechanisms which require high friction between the gear teeth but ideally low wear between ...
1
vote
1answer
510 views

How do I model the friction on a rolling pulley wheel, which holds weight, on a horizontal cable?

I am currently designing a motorized zipline trolley that will carry a person on a horizontal cable, so I am trying to calculate the friction on the wheels to determine what kind of motors I need. I ...
0
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1answer
319 views

Are “interference fit” equations appropriate for calculating barrel stress?

I am curious about calculating stress at various points along a barrel as a bullet is being fired through it. The interference fit (press/friction fit) equations immediately come to mind, but I am ...
3
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3answers
145 views

Understanding net torque from an actuator

This will probably sound like a silly question, but here goes.... Let's say I have an actuator, with a torque rating of 1 Nm. I then connect it to a wheel, which starts rotating at a constant ...
1
vote
1answer
152 views

Apply constant load to an electric motor - low tech way

I want to know how much I can over-drive a small electric motor. Its speed at the rated voltage is too slow, so I want to find a higher voltage that won't blow it. It will only be used intermittently, ...
1
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0answers
53 views

how to calculate the speed ratio (Rotational speed to advancing speed) in friction stir welding

I am a student and I work in the friction stir welding of a hardened aluminium alloy 7075-T6, and I want to confirm about this information before I put it in the article. I found in the literature ...
3
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3answers
1k views

Is there any material that has a higher kinetic friction than static friction?

Is there a material that has higher kinetic friction than static friction? You can assume it's sliding on any surface you want. Better if you come up with one that has this property on a standard ...
7
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2answers
109 views

Adding a lubricant to an already lubricious material, how is CoF affected?

I have a dry film moly-graphite lubricant (CoF=.075) and a lubricious CVD coating (CoF=.05). The CoF of each of these lubricious materials was determined using the same ASME standardized test. The ...
0
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2answers
299 views

Can a 2 HP motor move a 1,000 lbs flat-bottom boat across a flat material surface?

There is a small 13' long x 6' wide, 1,000 lbs (total weight of everything) all-fiberglass white pontoon boat with dual flat-bottom fiberglass pontoons. (Each flat pontoon bottom is 2' in width, with ...
4
votes
1answer
584 views

Determine coefficients of friction based on the torque required to rotate a part on a shaft

I'm trying to model a part that rotates on a shaft. I measured empirically that it has a static torque of around 500 N·mm and a dynamic torque of around 400 N·mm. I want to simulate it in CAD but my ...
1
vote
1answer
563 views

Pacejka Formula - natural values

For my racing game I am using a simplified Pacejka Magical Formula: $\mu_{lateral} = \mu_{0} * \mu_{1} * D * \sin(C * \arctan(B * x - E * (B * x - \arctan(B * x))))$ Where: $\mu_{lateral}$ is ...
8
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2answers
2k views

Not a good idea to rub two of the same material against each other?

I've read that it's not a good idea to rub two surfaces of the same material against each other, e.g., plastic against plastic, metal against metal. Plastic against metal is preferred. Why is this the ...
4
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4answers
14k views

Why use bushings of different material than what they contact?

I've heard that materials that need to slide against each other should be of different materials. Why is that?
3
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2answers
502 views

Suggestions for low friction surface materials for a “beltless static treadmill”

I'm currently developing a treadmill for clinic gait research. If I were to build a flat treadmill with no moving surfaces what materials or coatings would be worth exploring as walking surface. ...
1
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1answer
620 views

Design of Wheels/Tires for a RC Car [closed]

Background Information: My design team is trying to create a small RC car that can climb a 30 degrees incline that is 6inches high. We have two motors on a 3 wheels vehicle with the motors powering ...
-1
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1answer
416 views

Sumo-bot Wheel Help - Sticky tires or Wide & less friction tires? [closed]

I am building a sumo-bot and our competitors have thin sticky tires, while we have wider and less sticky tires. The diameter is the same, and the gearbox/motor is the same. Who will win? PS: Sticky ...