DrD

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DrD last won the day on October 1

DrD had the most liked content!

About DrD

  • Rank
    Member

Profile Information

  • Gender
    Male
  • Location
    Iowa, USA
  • Interests
    Kinematics, dynamics, mechanics of materials, Theory of Machines, machine design, vibrations
  • Present Company
    Machinery Dynamics Research
  • Highest Qualification
    PhD
  • Engineering Qualification
    Registered Professional Engineer, TX, WI (Ret'd)

More Information

  • Achievement /recognition/ Certifications
    Consulting work for a variety of industries, particularly in the IC engine related area (Torsional vibration analysis, shaking force analysis, engine cam design, system simulation).

    Author of several books, including one widely used textbook for Theory of Machines.

    Life Member ASME
    Member SAE
    Member SNAME
  1. 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
  2. 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
  3. 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
  4. 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
  5. 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
  6. Gears

    Wow!! That was absolutely fascinating!! A blank page! Who can possibly top that? DrD
  7. How To Become An Expert

    I'm glad you thought so. DrD
  8. 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
  9. I think a person would have to be NUTS to take this position. The money, $5300/mo. sounds like a lot, but look what you would have to give up and where you would have to live. NO THANK YOU!! The money comes out to $63600 per year (tax free they say), but that is far less than most MEs are making in the USA. DrD
  10. Wind Tirbune Vibration Problems

    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
  11. 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
  12. 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
  13. Mechanics Corner A Journal of Applied Mechanics and Mathematics by DrD, # 44 Machinery Dynamics Research, 2017 Mouse Trap / Pendulum Dynamics Challenge - Part I Introduction Mice are a problem all over the world, and as a result, I'm sure that there are mouse traps of various sorts found everywhere. It would be utterly amazing if this were not true! In the USA, there is a very common type of mouse trap that I have seen used all my life, the sort of system shown below in Figure 1. I want to spend a few minutes discussing this mouse trap, to be certain that all readers understand how it works, before moving on to the main part of the post. MouseTrapPendulumDynamics-1.pdf
  14. #43 Four-Bar / Toggle Linkage Mechanism

    Wow, Henry!! I freely admit to being older than dirt, but these books are old even for me! You are correct; they are very interesting. Sadly, many of the figures don't really tell enough to make clear how the things work. But some do, and that makes for fun browsing. Thanks, DrD
  15. #43 Four-Bar / Toggle Linkage Mechanism

    Been "speed reading" again, Henry? That is indeed an interesting image you posted. If I recall correctly, this is a variable compression ratio engine mechanism. It is particularly interesting that you post it here. It is another variant on the four-bar/toggle linkage idea. The crank, the link, and the radius bar form a four-bar linage. The connecting rod drives the crank through the link, essentially a slider-crank of a strange sort. This is a type of engine called an L-head engine, referring to the idea that the combustion chamber and the dead volume near the valves form an L-shape. It is interesting that one valve is in the block while the other is directly opposite in the head. I wonder how well that works? In a two-stroke cycle, you would risk pulling most of the mixture right through from inlet to outlet without burning at all! Most likely it is for a four-stroke cycle. DrD