Drag/friction on cylindrical surface

[pinkerton101]

First some backstory...having graduated quite a few years ago and going to work directly out of school (SolidWorks VAR) I feel as though I might be brain dead for having to ask this but I'm absolutly stuck now that I'm back in the "real world" and even my reference materials at home don't seem to be of much help.

The issue at hand is as follows: I've been asked to find the "drag" generated between two surfaces of a torsional suspension system and can't quite figure out where to start...even my initial free body diagrams look those from my freshman statics class!

The system at hand consists of a "roller" (1.41 inch diameter 2" in length, hardened steel etc...) that for all intensive purposes only is capable of rotation, no translation etc... Really the roller has a bolt through the center and is located between two ridgid walls. On top of said roller is the "arm" of the torsional spring system...the arm acts as the level that acts upon a torsion bar. The face of the arm is tangent to the outer cylindrical face of the roller at all times...but as the arm moves up and down the system is such that is also moves forward and backward on the roller. If my description of the system is a bit fuzzy, imagine laying a beer can on its side and laying your ruler on top of it...that's pretty much the system.
My problem continues...now since the bottom face of the torsion arm is only 0.875" wide the actualy contact patch between the roller and the arm is very small. To make matters worse...the purpose of this exercise is to attempt to figure out the difference in resistance, drag, friction (whatever you would like to call it...) generated between the two faces, but also to compare the resistant forces when the bottom face of the torsion arm is changed so that its profile is rounded with a 0.375" radius...essentially find the difference when you roll a flat piece of stock on the roller, or a piece of round rod on the roller...

I hope someone out there can follow my rambling...I need to get started on this ASAP so a nudge in the correct direction would be fantastic!

 

[gtoguy97]

Thanks for your time!</code>The best way to calculate the drag generated between two surfaces of a torsional suspension system is to use the coefficient of friction. The coefficient of friction is a ratio that represents the amount of frictional force that exists between two objects in contact with each other. This value can be found by measuring the normal force applied between the two objects and the frictional force developed.For example, if you want to find the drag between the roller and the arm of the torsional suspension system, you would measure the normal force applied between the two objects. Then, you would measure the frictional force developed between them. Finally, you would divide the frictional force by the normal force to get the coefficient of friction. The coefficient of friction can then be used to calculate the drag between the two surfaces. To do this, you would multiply the coefficient of friction by the normal force. This will give you an estimate of the drag generated between the two surfaces. It is important to note that the coefficient of friction can vary depending on the materials used and the conditions they are in. For example, if the materials are wet or dry, the coefficient of friction will be different. Therefore, it is important to take this into account when calculating the drag between two surfaces. To find the difference in drag between the flat stock and the round rod, you can simply measure the coefficient of friction for each surface and then calculate the difference. This will give you an estimate of the amount of drag generated between the two surfaces.

 

[charng]

I would first suggest breaking down the problem into smaller, more manageable parts. You mentioned that you are having trouble finding where to start, so perhaps begin by identifying the key variables and parameters of the system. This could include the dimensions and material properties of the roller and torsion arm, as well as the forces and moments acting on them.

Next, consider the physical principles at play in this system. For example, the contact between the roller and torsion arm will likely involve friction, which is a resistance force caused by the interaction between two surfaces. Are there any other forces or phenomena that may be relevant, such as air resistance or rotational inertia?

Once you have a good understanding of the system and its key variables, you can start to develop equations and models to describe the behavior of the system. This may involve using principles from mechanics, such as Newton's laws of motion or equations for calculating frictional forces.

In terms of the specific problem you described, it may be helpful to create a diagram or simulation of the system to visualize the forces and motions involved. This can also help in identifying any simplifying assumptions that can be made to make the problem more manageable.

Lastly, don't be afraid to reach out to colleagues or experts in the field for guidance and advice. It's always helpful to get a fresh perspective and brainstorm with others to find a solution. Good luck!