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Mechanics Corner

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A Journal of Applied Mechanics and Mathematics by DrD

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A Calculus Challenge

Mechanics Corner A Journal of Applied Mechanics and Mathematics by DrD, #45 (c) DrD, 2018 It has been quite a while since I last posted anything here, but an interesting problem has come to mind that I wanted to share with you. If you really know calculus, this should be straight forward; if you don't know calculus, don't even try! MEForumChallenge.pdf   ***********************************************************************************************************

DrD

DrD

 

How To Become An Expert

Mechanics Corner     A Journal of Applied Mechanics and Mathematics by DrD     © Machinery Dynamics Research, 2016 How To Become An Expert      Introduction     This is going to be another of those personal experience/opinion pieces, so if these bore you, be warned! This may be the time to click on something else.     A reader recently wrote to me asking how to become an expert. I have to tell you, I don't spend much time thinking about being an expert, but I suppose o

DrD

DrD

 

A Question for Readers

Many of you have asked me various questions, so now it is my turn. Let me lay a bit of background first, and then the questions.   I have had some conversations recently with JAG (one of the other writers here at ME Forums) regarding the choice of software for 3D modeling and analysis. JAG has made some excellent suggestions, specifically a cloud based program called Onshape. Unfortunately, for reasons that are unclear, my computer cannot run Onshape; I have worked with their help peop

DrD

DrD

 

A Community Built On False Values -- An Opinion Piece

A Community Built on False Values This may well prove to be the least popular thing I ever post on this blog because what I have to say may offend many. I do not say it with the intent to offend, but because I am compelled to give a warning. One of the most interesting things that has developed from my blog, Mechanics Corner, here on the ME Forum has been the opportunity to correspond directly with a modest number of readers. This has included both young men and young women scattered across In

DrD

DrD

 

#3 -- Kinematics Part I / Position Analysis

Position Analysis Introduction Many years ago, when I first began to study mechanics, the "conventional wisdom," expressed by both teachers and fellow students, was this: "Statics is easy, Dynamics is hard, and Kinematics -- who bothers to actually study kinematics? Kinematic relations, when needed, simply drop from the sky like rain, but nobody seriously studies kinematics." I eventually found the truth to be a bit more subtle: Statics of structures is generally easy, while the s

DrD

DrD

 

#20 -- A Question of Stability (Revised)

Mechanics Corner     A Journal of Applied Mechanics and Mathematics by DrD, #20     © Machinery Dynamics Research, 2015 A Question of Stability Introduction     The word stability in its several forms is widely used in nontechnical communication. A person whose life it highly consistent from day to day is said to have a stable life. When the political situation in a particular area appears to be unlikely to change, it is said to be stable. A person who is well balanced and un

DrD

DrD

 

#1 -- Introductions

Welcome to the first installment of Mechanics Corner, a feature that we hope will become a regular blog item on Mechanical Engineering Forum. The intent is that every week we will have a new article on some aspect of Applied Mechanics and Mathematics, things of broad interest to mechanical engineers. Some of these articles will be fairly elementary, while others will be considerably more advanced, but the idea is to have something for everyone. We will hope to amuse, entertain, and most importan

DrD

DrD

 

Where Will I Find A Job??

Where Will I Find A Job?? As I read over the questions that readers post here on ME Forum and elsewhere, I sense a common theme in many of them. There seems to be a wide, dare I say almost universal, concern about where those currently in college will find employment after graduation. To a degree this is entirely understandable; we all wonder what is in our future. Even so, the level of anxiety that I sense in many of your postings strikes me as extraordinarily high. Let us consider this a bit.

DrD

DrD

 

Becoming An Expert -- Part 2

Mechanics Corner     A Journal of Applied Mechanics and Mathematics by DrD     © Machinery Dynamics Research, 2016 Becoming An Expert -- Part 2      Introduction     In the previous article on How To Become An Expert, I covered a lot of points in generalities with some short anecdotes from my own experience. In this article and the next, I will describe in considerably more detail a critical period in my own formation, an time of considerable professional embarrassment w

DrD

DrD

 

Becoming An Expert -- Part 3

Mechanics Corner     A Journal of Applied Mechanics and Mathematics by DrD     © Machinery Dynamics Research, 2016 Becoming An Expert -- Part 3      Introduction     In the previous article on Becoming An Expert--Part 2, I mentioned that there were two big issues for the engineering analysis section at my Houston position, the first being the matter of seismic survivability and the second being torsional vibration. The first item was dealt with in Part 2, and in this art

DrD

DrD

 

The VEProject --- Shifted Levers --- A Critical Assessment

The VEProject --- Shifted Levers A Critical Assessment      Introduction     The subject of this article is the VEProject Shifted Lever video, as found at the following URL:   https://www.youtube.com/watch?v=8TniRMwL2Vg     The video shows a "Shifted Lever" mechanism, a device that appears to be perpetually off balance. It is presented as a perpetual motion mechanism, that is, a machine that will run forever without any energy input other than, perhaps, an initial push. This presentation c

DrD

DrD

 

Twenty One Rules for Tech Writing

Twenty One Rules for Tech Writing Introduction One of the things that has surprised me about the readers of ME Forum is the number of folk who want to publish technical papers. When I was an undergraduate (a very, very long time ago), publishing papers was the farthest thing from my mind. I knew that publishing was a concern for some of the faculty, but it was certainly no concern of mine! To my even greater amazement, most of those desiring to write want to write in English, even though this

DrD

DrD

 

Last Post -- Time to Hang It Up

Mechanics Corner     A Journal of Applied Mechanics and Mathematics by DrD     © Machinery Dynamics Research, 2017 Last Post Time to Hang It Up     This will be the final post of Mechanics Corner here on Mechanical Engineering Forums. It has run almost exactly two years, and there have been ups and downs along the way. In this final post, I want to reflect a bit on my original goals for the blog, and also on what has actually happened. When our host first proposed to me t

DrD

DrD

 

Puzzled (A Poll)

The response here at Mechanical Engineering Forums, or should I say, the lack of response, has left me puzzled. There was a modest response (as indicated by comments) to my first post, but the number of comments has dropped to almost nothing since then. I am only aware of one person who has actually worked on one of the challenge problems that I have posed (but I hope that there are more who have). In the previous poll, there have been a good number of views, but an extremely small number of peo

DrD

DrD

 

Verbal Description of a Doonesbury Cartoon

The following is a verbal description of a Doonesbury cartoon of unknown date by Garry Trudeau. Doonesbury has long been one of America’s major cartoon strips, with a very dry wit and a decidedly left-of-center outlook. I found this today in going through some old files. SCENE: A college classroom, the teacher lecturing in a rather absent minded fashion, the students silently bent over, taking notes and keeping their heads down. TEACHER: Of course, in his deliberations on American capi

DrD

DrD

 

#2 -- Box Tipping

Mechanics Corner A Journal of Applied Mechanics and Mathematics by DrD, No. 2 © Machinery Dynamics Research, LLC, 2015 It is a common practice for manufacturers to ship their products in packing crates that are strapped down on pallets for handling. There is often concern about the stability of this package as it is handled in transit to the purchaser. For this problem, we understand that the manufacturer wants to perform a simple test on each package shipped to assure that it wil

DrD

DrD

 

Something Light -- A few jokes

1. Team building is very popular in industry these days, so here is a team building joke. A group of mathematicians are attending a weekend seminar on team building. During the night, a fire breaks out in the room of one of the mathematicians. He quickly tears pages out of his notes and lights them on fire, one by one. He then runs down the hall, shoving burning sheets of paper under the doors of all the other mathematicians. In the morning, after the building is burnt to the ground, the fire

DrD

DrD

 

#4 -- Kinematics Part II / Velocity Analysis

Mechanics Corner A Journal of Applied Mechanics and Mathematics by DrD, # 4 © Machinery Dynamics Research, LLC, 2015     Vector Loop Kinematics -- Part II Velocity Analysis   Introduction In the previous article in this series, titled "Vector Loop Kinematics - Part I/Position Analysis" the idea of using closed vector loops for the position analysis of mechanisms and machines was introduced. This is an extremely powerful method; I have never found

DrD

DrD

 

Good News -- Bad News -- Rolling Disk in a Rolling Ring

Mechanics Corner     A Journal of Applied Mechanics and Mathematics by DrD, # 35       Machinery Dynamics Research, 2017 Good News --- Bad News Rolling Disk in a Rolling Ring      Introduction     Well, it looks like Mechanics Corner is back, at least in terms of an occasional post. It will probably be less frequent than previously, but there are just too many interesting things to talk about to remain entirely silent! The title for this post may leave you wondering wh

DrD

DrD

 

#43 Four-Bar / Toggle Linkage Mechanism

Mechanics Corner A Journal of Applied Mechanics and Mathematics by DrD, #43 (c) Machinery Dynamics Research, 2017   Four-Bar / Toggle Linkage Mechanism Introduction   I believe that it would be correct to say that all of the single degree of freedom mechanisms that I have discussed on ME Forums have involved only a single loop. This might lead a reader to conclude that a single degree of freedom implies only a single loop, and vice versa, that a single loop imp

DrD

DrD

 

ODE Solution --- Fail!!

Mechanics Corner     A Journal of Applied Mechanics and Mathematics by DrD, # 31       Machinery Dynamics Research, 2016 ODE Solution --- Fail!!      Introduction     Digital computation has become a major tool for engineers, and it is a great benefit. It can also lead to many pitfalls for the unwary. This note is about the latter, a potential pitfall that many engineers risk on a daily basis, most of them with little awareness of the danger.     Early in the developme

DrD

DrD

 

Braced Cantilever

Mechanics Corner     A Journal of Applied Mechanics and Mathematics by DrD, # 32     © Machinery Dynamics Research, LLC, 2015 Braced Cantilever Introduction     Anyone who has actually gotten into machine design is familiar with this difficulty. Consider the situation where a project is well advanced, many plans have been made, and it is all based on the assumption of the adequacy of one particular part. When you finally get to the detailed analysis of that part, the calculat

DrD

DrD

 

#5 -- Kinematics Part III / Accelerations

Mechanics Corner A Journal of Applied Mechanics and Mathematics by DrD, # 5 © Machinery Dynamics Research, LLC, 2015     Vector Loop Kinematics -- Part III Acceleration Analysis Introduction In the first article in this series, titled "Vector Loop Kinematics - Part I/Position Analysis" the idea of using closed vector loops for the position analysis of mechanisms and machines was introduced. A second article, "Vector Loop Kinematics - Part II/Velocity

DrD

DrD

 

Professional Responsibility — Do The Right Thing

Professional Responsibility — Do The Right Thing In Western culture, three professions are recognized. They are medicine, the law, and theology. The practitioners of these professions have long been accorded a special status in society in recognition of their special knowledge. The physician is expected to use his knowledge of healing only for good, and never to murder or maim a person. The lawyer is expected to give correct legal advice to his clients, to keep them free from legal entangle

DrD

DrD



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