Jump to content
Mechanical Engineering


  • Content Count

  • Joined

  • Last visited

  • Days Won


DrD last won the day on March 16

DrD had the most liked content!

About DrD

  • Rank

Profile Information

  • Gender
  • Location
    Iowa, USA
  • Interests
    Kinematics, dynamics, mechanics of materials, Theory of Machines, machine design, vibrations
  • Present Company
    Machinery Dynamics Research
  • Highest Qualification
  • 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

Recent Profile Visitors

The recent visitors block is disabled and is not being shown to other users.

  1. You are welcome to disagree, but I will stick by my statement. Numbers may influence emotions, but ultimately it is emotions that drive decisions. DrD
  2. It does not look to me like the red screw will significant change the belt tension which is the source of the brake torque. How do you envision applying/releasing this "brake"? DrD
  3. Unless you are a fully funded research organization, forget the idea of building a rail gun. It is exceedingly dangerous and expensive. That said, why would you want to use such an expensive material for the rails? Are you aware that electrical erosion is a major problem in the rails of a rail gun. A typical rail gun some years back (about 2006) needed new rails about every other shot. Also, while we are at it, what will you use for power? It takes a vast amount of current to drive a rail gun. Force varies with the square of current, but the multiplier is quite low. In the early 2000
  4. OK, got it. Now, you need to draw a free body diagram (FBD) for each mass. Show only real forces acting on the masses, no mass x acceleration terms. Do you understand that the force through a dash pot if proportional to the relative velocity of the end points? Once you have the FBDs, you should be able to write the sum of forces on each mass. DrD
  5. This is a strange situation. Why did you stick around to finish an ME degree if none if it interested you? Does that reason, whatever it may be, give you a hint as to what you should do with your life? DrD
  6. You have not given us a system diagram, so we have no way to know how the springs/dampers are connected to the masses (which masses connected to which spring or damper). This is essential information. Please provide it, and we may be able to help you. DrD
  7. Take a look at Post #25 (Feb,, 2016) on the Mechanics Corner blog at this site. You will find a somewhat similar problem worked in some detail. If that is insufficient, send me a message. DrD
  8. Sure, it is certainly possible to find many things regarding this mechanism. But what are b and d? Is it intended that the spring element is perpendicular to the lever? If not, then a better figure would show that it is clearly not perpendicular. This is important. DrD
  9. DrD


    There is a retired SR-71 on display at Eglin AFB, Florida. I was able to walk right up to it and touch the wings; it was pretty scary, even when sitting entirely still. Those of us that never flew still have some appreciation for the astounding engineering that went into these planes. Thanks for your comment, Dudley. DrD
  10. I think you are a bit confused one one of your engineering types. Specifically, I question whether it is appropriate to speak of a "financial engineer." I think that is nonsense. Finance is based on emotions and psychology at least as much as it is on hard science. I also have to ask, why did you make this video? What is the point? I must be missing something. I really did not learn much (other than about the "financial engineer"!) DrD
  11. Dudley, you wrote your "rant" back before the recent catastrophe in Texas and the rest of the south central USA. That even just reinforces what you said about the inadequacy of wind power. It is all "feel good" and not engineering at all. The same can be said of solar. We messed up (IMHO) back in the late '70s (or was it '80s?) when we walked away from nuclear power. By now, it is quite likely we would have solved the waste disposal problem, if we had continued to pursue it. As things stand, we are still on square one. This was a good post. Thanks, Dudley. DrD
  12. And this addresses the question how? DrD
  13. DrD

    Mine Hoist Problem, #54

    Dear Mark, After thinking further about your response, I finally decided that I should tell you more about the situation. The load to be lifted out of the shaft is a massive blob of pure gold, studded with 50 carat diamonds. Your team has been searching for it for months, and now it has been found. Now, do you use the primitive lift described in the problem, or do you place an order for the modern equipment you recommended? Oh, I should also add a couple of other factors that may influence your choice. The action all occurs at a very high altitude (22,000 ft above sea level
  14. It is far better for you to read the book. I have not done such problems since I taught a course where they were included in the Fall semester, 1969. My memory is a bit fuzzy, and I'd probably mislead you. DrD
  15. DrD

    Mine Hoist Problem, #54

    Thanks for your comments, Mark. If we complicated the problem as you recommend, it would be fa beyond the likelihood of anyone working it. As it is, I am unaware of anyone having work the problem. One of the big points that you evidently missed is the kinematic aspect. I am well aware that slopes that follow exactly parabolic form are exceedingly rare. It was never intended to represent any actual mine, but rather a hypothetical situation intended as an exercise for folks to develop their skills. DrD
  • Create New...