Can the braking force be significantly greater than the force acting on the brake structure?

[Art_sh]

Hello everyone. Question: is it possible to have a damper in which the braking force will be significantly greater than the force acting on the support that this damper creates?

[AI reference redacted by the Mentors]

For example, a practical problem: a body weighing 40 kg moves at a speed of 1.6 m / s, it is necessary to stop it in 0.1 s over a distance of 0.05-0.1 m. In this case, the force that will be transmitted by the damper to the support should not be more than 100 N.

 

[PeroK]

Do you have a diagram? If it's a wheel, then the brake exerts a torque on the wheel and (static) friction provides the linear braking force.

 

[berkeman]

Thread closed temporarily for Moderation.

 

[berkeman]

After removing an AI reference from the OP, this thread is now reopened provisionally. Please remember that AI references are not allowed in the PF technical forums. Thank you.

 

[berkeman]

Question: is it possible to have a damper in which the braking force will be significantly greater than the force acting on the support that this damper creates?

I agree with @PeroK that a diagram would be helpful. In the mean time, are you familiar with how leverage is used in braking systems?

For example, if you look at the front disc brakes of a motorcycle which are usually hydraulically actuated, you will see that the brake lever travel at your fingers on the handlebars is a couple of cm typically, while the motion of the brake pads in toward the brake disc(s) is a couple of mm. That leverage makes it so that your fingers can apply a lower force (through a longer lever arm) and still apply a high squeezing force on the brake disc(s). Does that make sense?

 

[Art_sh]

Sorry, I will take into account your requirement regarding ChatGPT and similar systems. Regarding my task:
a body weighing 40 kg moves along linear guides that are fixed to a support. We ignore the friction force at the moment. The body has an initial velocity of 1.6 m/s. This body must be stopped in 0.1 s. For the minimum distance. At the same time, the force of impact on the support should not exceed 100 N. According to calculations, the braking force should be approximately 640 N. Is it possible to somehow "hide" the impulse from the body to the damper inside the system with minimal impact on the support and dissipate over time?

 

[Baluncore]

No diagram.
Are the linear guides horizontal or vertical?
What type of damper, and where is the damper in the system?

 

[berkeman]

Regarding my task:

This sounds like a schoolwork task. Is it for schoolwork, or a real life work task?

And it sounds like you need to limit the force applied to the support structure while it stops the body's motion, but the time window you are given is too short?

 

[Art_sh]

 

[Art_sh]

No diagram.
Are the linear guides horizontal or vertical?
What type of damper, and where is the damper in the system?

horizontal guides. The task is to come up with a damper that will perform braking in a specified time and with the transfer of the minimum possible force to the support.

 

[berkeman]

horizontal guides. The task is to come up with a damper that will perform braking in a specified time and with the transfer of the minimum possible force to the support.

You haven't said yet, but this is almost certainly schoolwork. I will move this thread to the schoolwork forums for you now.

We require students to show their best efforts on their schoolwork assignments. Please show some force calculations and tell us your ideas for completing this task. Thank you.

 

[Art_sh]

This is not a school task, but a very practical one. And if you know how to hide the impulse of force inside the system, I will be very glad to help.

 

[Art_sh]

I am not an expert in mechanics and theoretical mechanics, I am an electronic engineer, but at the moment I have this problem, and I am looking for a solution.

 

[berkeman]

how to hide the impulse of force inside the system

You lessen the impulse by spreading the time over which the force acts. That is standard practice in recoil-absorbing systems in firearms, for example. What is the source of your 100ms time limit?

 

[Art_sh]

strict stop time of 100ms - a condition that cannot be changed. It is determined by the technological process.

 

[berkeman]

Then the impulse has a lower limit defined by that time.

 

[vela]

If you have the body collide elastically with another object of equal mass, it will transfer all of its momentum to the object in just the collision time. Then you could bring the object to rest over a longer time, so that the force on it never exceeds 100 N.

 

[kuruman]

If you have the body collide elastically with another object of equal mass, it will transfer all of its momentum to the object in just the collision time. Then you could bring the object to rest over a longer time, so that the force on it never exceeds 100 N.

When you say that the body will transfer all of its momentum to the target object, doesn't this mean that the projectile body's momentum will be zero at the end of the collision time? How can it lose all its momentum and not come to rest? What am I missing?

 

[vela]

When you say that the body will transfer all of its momentum to the target object, doesn't this mean that the projectile body's momentum will be zero at the end of the collision time? How can it lose all its momentum and not come to rest? What am I missing?

Yes, the initial body comes to rest quickly, which is what the OP wants. The object which absorbed the momentum can then be brought to rest more slowly.

 

[hutchphd]

One must be careful to define what body or body parts must be 'brought to rest'. If the body is capable of any deformation, then, say, a light external shell could be brought to rest while the interior (and the overall CM) continues forward for a while. This is a shock absorber. Also the use of braking rockets is an extreme form of deformation..
I think otherwise you have a Newtonian conundrum.....

 

[Steve4Physics]

To follow-on from @vela's suggestion:

where the damper is a hydraulic buffer (available in a wide range of sizes and damping).

 

[Art_sh]

Thank you for your answers, below I have drawn my concept of such a damper. A linear generator-motor creates braking force and recuperates energy or simply heats the air with ballast resistors. The stators are suspended from the support via springs. Can someone evaluate this concept? Thanks in advance for your answer.

 

[hutchphd]

Thank you for your answers, below I have drawn my concept of such a damper. A linear generator-motor creates braking force and recuperates energy or simply heats the air with ballast resistors. The stators are suspended from the support via springs. Can someone evaluate this concept? Thanks in advance for your answer.

Your original post question has been answered in the affirmative...... There are many ways to accomplish it. Your design lacks sufficient detail for analysis (by me at least) but seems overly complex.

 

[Steve4Physics]

Thank you for your answers, below I have drawn my concept of such a damper. A linear generator-motor creates braking force and recuperates energy or simply heats the air with ballast resistors. The stators are suspended from the support via springs. Can someone evaluate this concept? Thanks in advance for your answer.

Not sure what the blue block in your diagram represents and to what it’s connected.

Presumably your diagram is a ‘bird’s eye view’ as you previously said the guides are horizontal.

Also,not sure what overall approach you are considering. Is it the additional 40kg block as originally suggested by @vela in Posts #17?

Unless energy-recovery is essential, why not use a spring/hydraulic damper? It’s simpler, cheaper, readily available and probably more reliable than a linear motor.

More generally, you need to be aware of the following.

The kinetic energy that needs dissipating is $\frac 12 mv^2 = \frac 12 \times 40 \times 1.6^2 \approx 50$ J.

Let’s assume all of this energy is eventually dissipated by the damper.

The force transmitted by the damper to the support should not exceed 100N, That means the minimum distance the damper can move ($W=Fd$, so $d = \frac WF$) is $d = \frac {50}{100} = 0.5$ m approx. And then you need some safety margin. So, say, a 1 m ‘damping distance’ might be needed – which sounds a lot!

Should you be designing such a system? It sounds quite specialised and it sounds like (being an electronics engineer) you do not have the necessary background. There may be safety and liability issues to consider.

 

[Art_sh]

You are right, I have no experience in developing such systems, so I am looking for a designer who can design such a damper. Using a linear motor/generator has the advantage that I can set almost any profile of the braking force depending on the velocity of the body. However, I do not know how to model and calculate this concept. I can send a 3D step file.

 

[Art_sh]

If there are any other ideas on how to "hide" the impulse and then smoothly release it, I would be very grateful.