Category: My Blog

2-D Mechanism Synthesis

Mechanism design and linkage synthesis is interrelated to each other. While kinematic analysis of any mechanism is done with the known math tools. However the inverse is quite complex.

For a given/designed mechanism, it is pretty easy to generate the motion of the mechanism, as the fundamental principles are taught to  mechanical engineering junior students. However it is not taught how to design a mechanism that draw a specific motion.

You can design any 2D mechanism in order to follow such a specific trajectory, with this application:  MotionGen (https://www.stonybrook.edu/commcms/motiongen/index.php) . The application was created by Anurag Purwar (Stony Brook University). Here is short demonstration he presented:

The theory behind the MotionGen app is presented here in this video:

A Scientific Film : HIDDEN FIGURES

When I was with mathematicians, they were only talking about “proof, theory, fields, groups and rings and such things like that I don’t even have no idea”. When those mathematicians told me that they would watch a movie, I was surprised! I was thinking into myself that they don’t watch any movie, but they only do math!

The name of the movie which those mathematicians suggest was “Hidden Figures (2016)“. That movie was pretty fine, even though it was ‘HOLLYWOOD’ movie (I hate Hollywood movies actually).

In that movie, we can see how mathematics play a very critical role for the technology (Space Race between USA-USSR). Because of USSR pure mathematicians were so good at math, Russia was able to go to the space first, but America had to followed them after some time as a second nation who went to space. And even come back to earth again. Underlining of ‘And even come back to the earth’; because going to the space is easy part, but coming back to the earth safe is the more difficult part comparing for the first part.

Anyway, if you haven’t watched the movie before, I strongly recommend the movie for the engineers, or anyone who likes technology, computers, or space. We can see the real meaning of computer (not the machine one, but human computer). And how the new technology(coming of the first programable machine computers) affects the  human computers.

Applications of Kinematics

Ferdinand Freudenstein(12 May 1926 – 30 March 2006) who is being described as “Father of Modern Kinematics” has made great contributions to the kinematics and mechanics. As it is said that he had mentored 500 PhD students(That’s amazing and unbelievable!). One of them his student was  Arthur G. Erdman (now Professor at University at Minnesota, Mechanical Engineering Department, link to his website). Professor Arthur G. Erdman is giving a seminar related to why “Kinematic is a dead field” now as he said.  (It is a joke! Don’t waste your time to search the video how kinematics is dead!).

He is giving examples from very different areas where kinematics principles are applied. Therefore this video/ or slide might be used for the inroductory lecture session for the lecture of “Kinematic Design” or “Machine Theory”. He gives many great useful examples from daily life. Any lecturer might present this video on the first lecture of Machine Design, or he can give this video to the student as a homework to watch.

Additionally here you can find here another similar video from Dr. Bernard Roth (another PhD student of Ferdinand Freudenstein 🙂 ).

THE BLIND MEN AND THE ELEPHANT

THE BLIND MEN AND THE ELEPHANT

It was six men of Indostan
To learning much inclined,
Who went to see the Elephant
(Though all of them were blind),
That each by observation
Might satisfy his mind.

The First approached the Elephant,
And happening to fall
Against his broad and sturdy side,
At once began to bawl:
“God bless me! but the Elephant
Is very like a WALL!”

The Second, feeling of the tusk,
Cried, “Ho, what have we here,
So very round and smooth and sharp?
To me ’tis mighty clear
This wonder of an Elephant
Is very like a SPEAR!”

The Third approached the animal,
And happening to take
The squirming trunk within his hands,
Thus boldly up and spake:
“I see,” quoth he, “the Elephant
Is very like a SNAKE!”

The Fourth reached out an eager hand,
And felt about the knee
“What most this wondrous beast is like
Is mighty plain,” quoth he:
“‘Tis clear enough the Elephant
Is very like a TREE!”

The Fifth, who chanced to touch the ear,
Said: “E’en the blindest man
Can tell what this resembles most;
Deny the fact who can,
This marvel of an Elephant
Is very like a FAN!”

The Sixth no sooner had begun
About the beast to grope,
Than seizing on the swinging tail
That fell within his scope,
“I see,” quoth he, “the Elephant
Is very like a ROPE!”

And so these men of Indostan
Disputed loud and long,
Each in his own opinion
Exceeding stiff and strong,
Though each was partly in the right,
And all were in the wrong!

by John Godfrey Saxe (1816-1887)

I came across that poem to describe what assumptions we do while we create the mathematical model of a physical system. (from the book of Fen, Mühendislik ve Sosyal Bilimlerde Matematiksel Modelleme, Nuri Özalp, Gazi Kitabevi Yayınları, 2015)

That poem example explain so well about our assumptions in mathematical modelling: the model might work for that particular part, however it is not exactly whole. With our mathematical model; We are right , we are also wrong at the same time.
However, for engineers the purpose is to make/create something useful for humanity, even though our model is wrong in some part.