DrD

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DrD last won the day on June 17

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. Dear Bob, What you have drawn is simply a form of a slider-crank mechanism, and well known mechanism described in countless sources. Do a Google on that name and you will find more information than you ever imagined. DrD
  2. Is this club going anywhere? Where is out leader, the club owner? What does he do if not provide leadership and direction? I ask again, is this club going anywhere? DrD
  3. Mechanics Corner A Journal of Applied Mechanics and Mathematics by DrD, #39 (c) Machinery Dynamics Research, 2017 Comments on a Textbook Theory of Machines by R.S. Khurmi & J.K. Gupta 1 Introduction Recently, through the wonders of the Internet, I have come across a copy of the textbook Theory of Machines by R.S. Khurmi and J.K. Gupta (S.Chand & Co., Ltd., 2005). Since theory of machines has been my primary technical interest since the early 1980s, I was interested to see what would be in this book, particularly in view of the many favorable comments posted in regard to it. Many people seem to think that this is a most excellent book, and I’m always interested to see what brings forth comments of that sort. As I looked through the Table of Contents, I saw that one of the last chapters was given to the topic of Torsional Vibrations (Ch. 24). Since the area of torsional vibrations has been a topic of intense personal interest for 40+ years, I was naturally drawn to this chapter. The comments that follow are based on what I found in that chapter; I have not reviewed the remainder of the book at all. In my comments below, I will refer to the authors, Khurmi and Gupta, simply as K&G to avoid writing their names out repeatedly. One of the things I think is necessary in a textbook is that it should be directed toward teaching students to solve real problems, not simply textbook examples. Certainly, textbook examples should be simple so that they can be easily understood, but they should also be as general as possible. Where they involve special, limiting assumptions that may likely not be true in actual practice, this should be made clear. Failure to do that marks an author as one who has never actually done engineering in the real world. If the assumptions are not made clear, there is a tendency for students to later want to simply apply directly the results from the textbook problem, not realizing that they may not apply at all. So, what did I find? Comments on Textbook - Khurmi.pdf
  4. New Blog Post

    When you ask about IT, I presume that is the same IT I spoke about when I wrote "Where would you publish IT"? Is that what you had in mind? For the blog post, I had not particular thing in mind, but most probably a technical paper presenting some sort of engineering solution. It could also be a book, but for that, it is a bit easier to locate a publisher. DrD
  5. You are asking for a huge amount of help. The design of such a device is a very large project, one that will take many hours. I strongly suggest that you start your design, do the preliminaries, and then ask questions about specific details. DrD
  6. Not my area either. I really do not want to lead you astray, so I better stay out of this. DrD
  7. Rocket Homework Problem

    This comment removed by DrD.
  8. Over at Mechanics Corner, there is a new problem posted involving a rocket on a launcher. This is made to order for folks interested in Kinematics of Machines, so be sure to go read the post and solve the problem. DrD
  9. Rocket Homework Problem

    Mechanics Corner A Journal of Applied Mechanics and Mathematics by DrD, #38 Machinery Dynamics Research, 2017 Rocket Homework Problem Introduction Most engineers find problems involving rockets to be exciting. There is something about a rocket that fires our imagination, whether we think of going to the moon or one of the planets, or simply of shooting down an incoming missile. The subject of this post involves a rocket on a mobile launcher. The rocket is intended to be transported in a horizontal position, but it must be elevated in order to be fired. Both positions are shown in the accompanying figure. Read the attached PDF for more on this problem. RocketHWProblem.pdf Addendum: One reader has posted a proposed solution for this problem as a comment. It was not my intent that solutions be posted in the comments at all. I only want solutions sent to me by the personal message system. DO NOT POST YOUR SOLUTION IN THE COMMENTS!! Regarding the solution that has been posted, let me say the following: 1. Some of the answers are correct, while others are not. Do not be misled into following this solution because there are errors therein. 2. Even where the results are correct, there are a number of methods that I would not recommend using. Thus again, I say to all other readers, do not follow this solution, but work it out for yourself. 3. Be sure to document your solution, so that if someone else were to ask how you obtained a particular result, you would be able to explain it in a clear and reasonable manner.
  10. @ HydraBob: How do you see a bell crank meeting this need? Can you explain, please? @ JAG: Its worth a shot. But I think it has risks as well. The confused questioner may simply accept whatever is proposed as an easy way out of having to think more carefully and express the problem better. Who knows?? DrD
  11. Sounds like JAG is proposing a face cam. Perhaps JAG understand what AAFAA wish to accomplish. I wish I could say that I understand as much! If the face cam that JAG proposes is indeed an acceptable answer, the motion analysis (determining position, speed, and acceleration) is just a simple kinematics problem. The big question, as I see it, is this: "Is this what AAFAA wanted to accomplish?" DrD
  12. Wow!! I'm totally confused. What is this, and what are you trying to accomplish with it? Does this thing exist, or is this simply some device you have imagined? DrD
  13. Hard automation tends to be heavy on mechanical engineering. I am thinking, for example, of cam controlled automated systems. I have seen a number of examples of this sort of automation, including (1) a pick-and-place robot that puts finished CDs in plastic cases, (2) a yogurt cup filling machine, where cams control the lowering of the dispenser nozzle, starting and stopping the material flow, and retraction of the nozzle, and (3) a paper cup making machine where all operations were cam driven to cut out blanks for a paper cup, roll the blank into the form of a cup, seal the edge, place a bottom in the cup and crimp the edge, and finally roll the top edge. In each of these cases, there were vast quantities of product to be produced in identical form. Soft automation, with electronic controls that enable different forms for the basic product lend themselves to things like automobile production where there are many variations on the basic car. Some cars will have one feature while the next on the order lacks that feature. Automated assembly must be able to adjust and compensate on the fly for these variations. While the assembly operation itself may remain largely a mechanical problem, the control tends to be more electronic using computer logic to adjust to each order. The word MECHATRONICS is a relatively new term, one that usually denotes systems that involve a high degree of electronic logic with a few mechanical components. This brings to mind things like tape recorders, CD players/recorders, cameras, phones, and similar products. I'd be interested to hear from other readers just what word do you use for electromechanical devices such as electric motors, generators, electric brakes, solenoid actuators, gear motors, etc? Does this fall under mechatronics in your thinking, or is there another term you think is more descriptive? DrD
  14. who can help me that? ( solid mechanical)

    I cannot help if it is not in English. DrD