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Mechanical Engineering

DrD

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DrD last won the day on October 13

DrD had the most liked content!

About DrD

  • Rank
    Member

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  • 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

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  1. The correct analysis of a track (much less the entire vehicle) is extremely complicated. Part of this is because the path of each component is not fully constrained; there is slack in the linkage. Modern software exists that can do this pretty well, but it is way too much for a hand calculation. DrD
  2. That's only partially true, Timothy. Yes, it does boil away, but no, it has not failed to accomplish anything. In boiling away, it has removed the heat of vaporization for the vanished water from the fire. That has the effect of slightly cooling the fire. Ultimately, this is a major part of how fires are extinguished, along with cutting off the oxygen supply. DrD
  3. Any sort of electric motor will require a source for the electricity. Electric motors have long fascinated the US Navy, particularly because of their control-ability. I'm not sure where that all stands today (I retired quite a while ago from the Navy civil service), but while I was there, the general conclusion that the weight and heat generated to manipulate the electric power required a second boat to carry it and supply the main boat through a long extension cord. I think you are likely out of luck on this problem. DrD
  4. This is a classic problem, one that entraps most beginners. Because it is a 2D problem, there are only three equations of motion possible. In spite of this, you say you want to determine 4 variables: Ax, Ay, Bx, and By. It cannot be done; this problem is statically indeterminate. You can determine the sum Ax+Bx, but you cannot determine either one separately. If you think your value for Ay is unreasonable, check your equations and your arithmetic. DrD
  5. I am not an FEA person, but I see some possibilities for your problem. 1) Your XYZ coordinate system is left-handed. I would imagine that the code expects everything to be expressed in a right-handed system. 2) The force that you show will move the two bodies apart, not force them together. This should lead to no deformation in either body. DrD
  6. Mechanics Corner A Journal of Mechanics & Mathematics by DrD, #54C Mine Hoist Problem, Hint #3 Introduction The original Mine Hoist Problem was posted 23 August, and it is not 10 October, over 6 weeks later. Thus far, I have not received any attempts at a solution. In this third (and probably last) hint, I want to explore some new ideas and also re-work much of the second hint in vector form. It will be useful to have the previous hints and original problem statement in hand as you read this.
  7. Still no responses, here quite a long time after the problem was posted. This must really be a trivial problem to attract so little interest, even though I thought it was reasonably challenging. Oh, well ... DrD
  8. I suggest that you talk to the application engineers at your proposed vendors that you will buy this system from. DrD
  9. Dudley's advice is certainly good. Co-Op is a chance for you to experience the job before you graduate, and also a chance for the company to get a good look at you. Co-Ops often receive job offers upon graduation. DrD
  10. DrD

    Snail Cam

    Why not use a lever mechanism to amplify the motion? DrD
  11. Mechanics Corner A Journal of Mechanics & Mathematics by Dr.D, #54 B Mine Hoist Problem, Hint #2 Introduction The original Mine Hoist Problem was posted 25 August 2020, and the first Hint was given on 8 September. We are now almost one month into this problem, and thus far no one has sent me even so much as a question other than Tim Dennison's request for a video. I'm not quite sure how to understand this. I see two basic possibilities: 1.The problem is so dull and uninteresting that no one could possibly
  12. Sounds like you are narrowing your question to friction losses in the rack and pinion only, exclusive of the guide mechanism. This depends upon the details of the tooth design (arc of approach/arc of recess) and upon the lubrication. If done well, these will probably be small relative to the friction in the guides. DrD
  13. Friction will be a major problem, and it all depends upon how you guide the moving member. What do you plan to use as a guide? There is simple sliding contact, various ball or roller guides, etc. A lot depends upon your budget, but the better the guide quality, the easier your system will work. DrD
  14. It appears that only a very few folks are even attempting these problems, but it also appears that no one has sent me a solution. For that reason, a small hint seems to be in order. Hint: Turn the picture upside down. For most of us, it is conceptually easier to think about the problem if the X-axis goes to the right and the Y-axis is upward. Of course, if you do this, you must recall that gravity then acts up, not down. Don't be shy; give it a try!!
  15. Was there supposed to be a question or a comment hidden in there? DrD
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