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Why Designs Fail ?

With so much scientific tools, why do designs fail?Why the unsinkable Titanic sank? Why did the thoroughly tested Columbia space shuttle burned out on return? Why Toyota had to call back thousands of cars designed by expert engineers?Design might fails because somebody made a stupid mistake in his calculations, like in the old joke about the bridge that fell down because the engineer forgot to multiply by two. It might happen, but it is extremely rare. Most design failures happen because one spe

Bumo

Bumo

 

Asking the correct questions for FMEA

An article appeared in an engineering forum entitled Why Designs Fail. As I thought about the article and the examples presented, the Titanic, Tacoma Bridge, etc., I realized mitigating the consequences of a failure are more important than preventing the failure. One of the subjects I did not learn in the classroom was Failure Mode and Effect Analysis (FMEA). I do not intend to cover the subject of FMEA but would like to emphasize one small portion. FMEA was introduced to me on my first jo

JAG Engineering LLC

JAG Engineering LLC

 

#27 -- Analytical Design -- Part II

Mechanics Corner     A Journal of Applied Mechanics and Mathematics by DrD, # 27     © Machinery Dynamics Research, 2016 Analytical Design -- Part II      Introduction     In Part I of this series, the problem posed was to apply, as far as possible, the available knowledge of mathematics and science to the design of an Emergency Steam Shut-Off Valve, to be gravity driven as in the sketch below, Fig. 1. The inlet and outlet for the steam flow are both specified to be 0.85

DrD

DrD

 

#26 -- Analytical Design -- Part I

Mechanics Corner     A Journal of Applied Mechanics and Mathematics by DrD, # 26     © Machinery Dynamics Research, 2016 Analytical Design -- Part I      Introduction     On ME Forums, there have been a number of questions raised about design. Many students are writing in asking for ideas for a senior design project, others are asking for help with a design problem, etc. There has been some discussion about "Just what is design?" That was definitely a question in the min

DrD

DrD

 

Professional Societies -- Or Not?

Mechanics Corner     A Journal of Applied Mechanics and Mathematics by DrD       Machinery Dynamics Research, (c)  2016 Professional Societies -- Or Not? Introduction     This post is written in response to questions raised by one of our regular participants, a young engineer in Australia. What I have to say here is based entirely on my own, very American, experience, and others may have different ideas. I would encourage a general discussion in the comments, so that we may see

DrD

DrD

 

War Stories

Mechanics Corner     A Journal of Applied Mechanics and Mathematics by DrD     © Machinery Dynamics Research, 2016 War Stories -- Dr. Jack Levedahl Today I want to tell a few war stories, war stories in the literal sense of the word, in that they all relate in one way or another to World War II. They all center on my friend Dr. Jack Levedahl, a most excellent mechanical engineer and adventurer. Jack was an elderly man when I first met him about 15 years ago, and he has since passe

DrD

DrD

 

#25 -- A Textbook Statics Problem

Mechanics Corner     A Journal of Applied Mechanics and Mathematics by DrD, # 25     © Machinery Dynamics Research, 2016 A Textbook Statics Problem      Introduction     In the course of each day, I visit many web sites, always keeping an eye out for interesting engineering problems. The problem that is discussed here is one such that came from an American site (more about that web site later). The problem was presented as a simple statics problem, and the poster was ask

DrD

DrD

 

Define your terms

A warning by Dr. D. posted on this site reminded me of two funny incidents. Dr. D. was responding to the use of PPM for perpetual motion machine. These initials according to Dr. D. are used for Permanent Magnet Motor. This may sound trivial, but the following, I was not warned about in school. If you have ever worked in big corporations especially defense or government related there are new languages you will need to learn. Shortly after joining a defense company, I told my boss if I did

JAG Engineering LLC

JAG Engineering LLC

 

Torsional Stiffness of a Shaft - Part III -- #24

Mechanics Corner     A Journal of Applied Mechanics and Mathematics by DrD, # 24     © Machinery Dynamics Research, 2016 Torsional Stiffness of a Shaft -- Part III         Introduction     The discussion in previous parts of this series has focused on stiffness (or compliance) estimates for various shaft geometries. There has been nothing said yet about joining parts together, although most readers will readily agree that integral (single piece) shaft assemblies are very rare

DrD

DrD

 

Torsional Stiffness of a Shaft - Part II -- #23

Mechanics Corner     A Journal of Applied Mechanics and Mathematics by DrD, # 23     © Machinery Dynamics Research, 2016 Torsional Stiffness of a Shaft -- Part II          Introduction          In the previous post of this series, a variety of shaft forms involving both solid and hollow sections were considered. A general approach was developed, applicable to various sorts of non-uniform shafts, but always subject to the provision that the variation in section was gradual; n

DrD

DrD

 

VW Dieselgate - really a suprise?

I have learned to take most news reports with a pound of salt. The VW diesel scandal may deserve at least a pinch of salt. That is my take from the attached article, “VW Dieselgate…” Most who have taken exams to receive their medical, law, or engineering licenses would likely not pass the exam on any given day as normally administered. I am sure I could solve a sufficient number of problems to get a passing grade on a PE exam but not in the 8-hour window. In the real world, our clients

JAG Engineering LLC

JAG Engineering LLC

 

Torsional Stiffness of a Shaft -- Part I -- #22

Mechanics Corner  A Journal of Applied Mechanics and Mathematics by DrD, # 22 (c)  Machinery Dynamics Research, 2016 Torsional Stiffness of a Shaft -- Part I          Introduction          A shaft is a common machine element, used to transmit rotational motion and torque from one component to the next. It is clear that the length of the shaft must be sufficient to span the distance from the first component to the second, but what should the diameter be? The answer to this quest

DrD

DrD

 

Challenges before Mechanical Engineers

Challenges Before Engineers The unintended outcomes of past engineering solutions to the problems have adversely affected environment. Environmental sustainability, health, reducing our vulnerability adding to the joy of living is essential for humanity to flourish. This forms challenges not only for engineers but also to others.The challenges relate to energy and the environment, health and medical sciences, education and information technology, infrastructure and security. Through creati

Bumo

Bumo

 

Inayat Durrani

What will happen if we condense the exhaust gas of coal gasification after passing through the gas Generator and then feed it to water treatment plant and then drain that water to the ground or reuse it. Can this be possible? No exhaust gas or reduced exhaust gas issue to environment.

inayatdurrani

inayatdurrani

 

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

 

Is Form Fit and Function Sufficient for Interchangeability?

My answer to that question would have been yes, and like all absolute answers, it would prove to be incorrect. An axiom in manufacturing is that the design engineer should not dictate manufacturing processes unless it is vital to the function of the design, metal vs. plastic, casting vs. forging etc. Once passed the gross requirements, dictating which machine tool to use would be beyond the design engineer’s prerogative unless there was a compelling reason! However, this should not be taken as t

JAG Engineering LLC

JAG Engineering LLC

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