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Mechanical Engineering


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Everything posted by DrD

  1. It is possible that I may be able to help you, but again, I may not. Please answer a few questions for me. 1) What college level math courses have you taken? 2) What college level mechanics courses have you taken (statics, dynamics, vibrations, theory of machines, etc)? 3) Where are you located? 4) Are you able to pay for tutoring? DrD
  2. A brake is a brake is a brake. Any brake has the potential to stop any rotating object. Whether it is a good idea or not is another matter, but certainly an automotive caliper brake has the potential to stop a winch drum. You really need to learn the difference between "brake" and "break." They are entirely different words, even though they sound alike in English.
  3. Wow! That was one boring video! I could not stay interested enough to watch it to the bitter end. The whole idea seems ludicrous. If you want to generate energy by human effort, why not apply it directly? Perhaps simply ride a bicycle, rather than try to generate electric power by pushing things. Talk about grasping at straws ...
  4. I rather doubt that you will ever get to the point where you fully understand the problem. Most of us find that there is always something more we can learn. At the same time, it seems foolhardy to commit to designing something about which you know so little. There is nothing about which I know everything, yet I would undertake to design some things but not others. I would design those things about which I already know enough to make a good start. I would avoid attempting to design something about which I now know nothing. Do you see the difference? DrD
  5. What a fabulous post! Not a complete sentence in it, just a string of terms describing destruction and destructive devices. This makes no sense at all, so it is posted in exactly the proper place. DrD
  6. What a great idea to commit yourself to a project you know nothing about! This is utter foolishness!! Engineers do not do such things. DrD
  7. What are Z-Kinematics U-Kinematics? I've never heard these terms before, so I'd be interested to know what you are talking about.
  8. DrD

    Two Short Math Problems

    I really don't think I can help you. I don't know much about robots. DrD
  9. Why in the world do you want to put a flywheel on a DC motor? The purposes of a flywheel are (1) to smooth out irregularities in the rotational motion of the shaft (torsional vibration), and (2) to store energy in order to continue operation though a power interruption. You did not mention either of these, so I ask again, "why do you want to put a flywheel on a DC motor?"
  10. "It gives balance to engine and load is uniformly distributed in crankshaft." This statement is totally incorrect. Torque is delivered to the crankshaft as a series of pulses, in no way uniform. In a multicylinder engine, torque will be positive at one location while it may be negative at another. What is a "four stage engine"? Do you mean four cylinder, or perhaps four stroke, or something else? All the pretty animations in the world are not worth much if the accompanying statements are nonsense. DrD
  11. The PDF file below will show you how to solve this problem. DrDPlanetaryProb.pdf
  12. As a starting point, you must know the MMOI for each individual component; without that, you cannot begin. Assuming that the individual component MMOI values are known, do a kinematic analysis of the planetary train to determine the velocity of the CM of each component. The use that information to formulate the kinetic energy of the entire system, all moving according to the kinematic relations. You will have to choose some rotation as a reference value, usually either the input or output rotation. The kinetic energy will have the form T = (1/2) theta-dot^2 (term1+term2+...+termlast) where theta is the reference rotation. The sum of terms indicated is the effective MMOI for the gear train. DrD
  13. Wow!! That was super exciting!! DrD
  14. The material you posted (from a book?) is only partially visible, and cannot be completely read. The various symbols are not defined, such as Ftc, Rc,T, Wc, and alpha_c. There is no way anyone can help you with so little information. Rather than ask for help, I suggest you draw the picture and work it out for yourself. You will learn much more that way. DrD
  15. The one thing that is very clear from your two URLs is that there is no uniform, well defined definition of "rifle barrel harmonics." There seems to be a mix of ideas about compression waves traveling down the length of the barrel and reflecting back combined with a dilatational wave propagating out from the charge ignition. The word "harmonics" seems to be more of a buzz term, to dignify the confusion. Altogether, this is simply an elastic wave propagation problem, albeit a complicated on due to the geometry involved.There are lost of people around the world who have studied wave propagation problems, and I'm sure that with the necessary experimental facilities, all of this could be studied experimentally. It may already be under investigation, either by the US Army (such as Picatinny Arsenal), or one of the rifle manufacturers (Remington, Winchester, etc). You will find the necessary mathematics quite sophisticated and well beyond the typical college graduate (lots of partial differential equations). Have fun with your inquiry. DrD
  16. The term "rifle barrel harmonics" is not one that I recognize, and could be used to describe several possible phenomena. In order to help you, I have to ask you to describe just what sort of motions you are concerned with, what phenomena it is you wish to describe. Please write out (in words) what you think happens that interest you, and then we may be able to offer some help with the mathematical description. DrD
  17. The term "Pan and Tilt Control System" does not have a universal definition, so no one can be sure what you are talking about. If you want help, give a detailed description of what you need to build, including one or more sketches of the proposed system. Only than can anyone give you a meaningful answer. DrD
  18. Without more details, it is difficult to say very much. One thought that comes to mind is that you have probably neglected friction which can be very significant in a system such as this. If you want more help, please post a sketch of your system with dimensional details. DrD
  19. Wow!! That was absolutely fascinating!! A blank page! Who can possibly top that? DrD
  20. DrD

    How To Become An Expert

    I'm glad you thought so. DrD
  21. Your drawing in and of itself will not cause or prevent vibration. Its all in the way the rotor is built. You have stated a desire, but you have not asked a question. Is there anything preventing you from accomplishing that which you desire? DrD
  22. The question is so broad as to be unanswerable. Yes, there can be vibration problems in wind turbines. But there are so many possibilities that it would require a whole library to address them all. Please be much, much more specific. DrD
  23. Really, Henry!! Brain cells boiling ... over a simply little mouse trap? You must have a very low boiling point! No, this is not the same mechanism as a trebuchet, although that too is an interesting problem. Cool down a bit and give this a try. It really is not so impossible. DrD
  24. Be sure to check out the new post at Mechanics Corner. It poses a challenge problem for each of you to work on. Do you really know kinematics of machines? Find out!! Try the simple problem posted over at Mechanics Corner now. DrD
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