Things every Mechanical Engineer must know

1. NEVER loan out your copies of: Machinery’s Handbook Shigley’s Mechanical  Engineering Design Making Things Move: DIY Mechanisms for Inventors, Hobbyists, and Artists (okay this one is a shameless plug, but my friend told me it’s “destined to be be a classic of sorts” so you can blame him)

2. Project planning follows the rule of pi. Take how much time you think you can complete something in, multiply it by pi, and that will be the actual length of time it takes.

3. Parkinson’s Law: Work expands so as to fill the time available for its completion. Don’t give yourself too much time for a project or it will never get done. Speaking of done, check out The Cult of Done Manifesto. If it weren’t for the last minute, nothing would ever get done.

4. Everything is a spring.

5. If it moves and it shouldn’t, use duct tape. If it doesn’t move and it should, use WD-40.

6. Document everything you do. Someone will ask you to justify your design at some point, and “it kind of sort of looked right” is never a good answer. This is especially true on collaborative projects. The group will forget who did what and it will make going back and changing things that much harder.

7. Design is an iterative process. The necessary number of iterations is one more than the number you have currently done. This is true at any point in time.

8. Ask questions. If you don’t know something, say so. Your credibility as an engineer lies not in being infinitely intelligent, but in knowing how to get at the right resources to figure it out. If you cheat, people will die.

9. Designing for disassemble is just as important as design for assembly. It will never work the first time you put it together. Oh, and make sure that everywhere there is a screw, there is a place for a screwdriver to install it. And for a hand to fit around said screwdriver.

10. Business will always be a part of engineering. Don’t work for free (unless you really want to) and don’t work without a contract. Don’t design a better mousetrap THEN expect someone to want it. The products that sell the best are not necessarily the ones that are technologically superior.

11. Design is based on requirements. There’s no justification for designing something one bit “better” than the requirements dictate. Better is the enemy of good enough. Get it done then go play outside.

12. Engineering is done with numbers. Analysis without numbers is only an opinion.

13. Be friendly and talk to your machinist and/or shop techs. You may have a fancier title or degree, but that does not make you better. A short conversation on how to make a part more easily machinable/moldable/etc. can save thousands of dollars and make you both look good. You may even learn something.

 

Classes every mechanical engineer should take.

The first class is machining, which should be fairly apparent from my title. I think all mechanical engineering students should learn how to machine something. Or, as MEs say, learn how to make chips. There are several reasons for this.

1. Mechanical engineers should be able to build things and know how things are built. In the real world, MEs probably aren’t going to be machining parts 24/7. However, they should know how something is machined and what processes they can use to machine stuff to better design parts/components/systems etc. It also will give MEs an appreciation for good designs that are easily machined.
2. Machining doesn’t require advanced math/physics skills. If students are coming in without AP credit and are following the course schedule, their first two to three semesters are Calc I, Calc II, Calc III, Physics I, Physics II, Chem, Writing, etc. For basic machining, you don’t need any of that. A machining course is perfect for a 1st year class because it has no prerequisites. And, it’s not a course that’s time consuming outside of class, relative to the Calcs, Physics, and Chems. So it’s not going to over-burden students.
3. It’s a good class to retain students or even draw students into ME programs. I know most of the first year classes are the so-called weed-out classes. At DrWife’s UG university, they called freshman engineers “pre-business” because so many drop out. While I don’t think fundamentally that everyone should be able to do engineering and people without the math skills even less so, a machining course is a good way to bridge that gap between theory and application. Yes, there’s this advanced calc and physics that can be difficult at times. But, you also get to build cool shit with your own hands. Someone who is on the fence may not hop over because of such a course.
4. Feedback from senior/grad students is that they want/need this in the curriculum to find competitive jobs. Several students I’ve spoken to say they have a competitive disadvantage over other students from other universities because they never had a machining course nor a project that they build with their own hands. They say that trying to describe to your potential future boss that you’re a really good mechanical engineer but you’ve never built anything during your undergraduate program is an oxymoron. If students can see that dilemma, why can’t we, as supposedly advanced educators with higher degrees, see that as well?

So, a machining course in a ME program, makes sense right? How about my second course that every ME should take? Wait for it…

There are some other courses that I think are useful as well. They are:

1. Computer Aided Drafting

(I don’t know how many time I’ve seen this skill listed on job posting. My suggestion is to learn Pro-E, AutoCAD, and SolidWorks. They are the three most widely use and if you can’t use any of these program well, it’ll be difficult to get any ME jobs)

2. Material Selection in Mechanical Design

(highly useful for any design work you’ll be doing in the future)

3. Strength of Materials

(I highly recommend keeping the textbook and notes for this course.)

4. Heat Transfer

(I highly recommend keeping the textbook and notes for this course.)

5. Technical Writing Course

(Very useful, not just for graduate school research papers, but for design or meeting reports for future work).

These courses apply most to design engineering. I might be missing a few courses, but definitely should make a note of these.

 

I will also  recommend the following in order of importance..

1. Experience with prototyping in lathe machine, at least the knowledge of the process flow. Most important because modeling in software is easy, not making it in real life.

2. Software for solid modeling - Solidworks (easy to learn, lots of tutorials available)

3. Good knowledge of basic mechanics, strength of materials or fluid mechanics and mechanism design.

4. Presentation skills - Microsoft Excel, Powerpoint, Word, LaTeX

5. FEM or CFD and software - Ansys/Abaqus/Comsol

6. Numerical methods with Programming - MATLAB/C++/Mathematica/Python

I.E.S EXAM PATTERN and SUCCESS TIPS

IES Exam Pattern
1. The Examination shall be conducted according to the following plan:
Part I— The written Examination will comprise two sections—Section I consisting only of objective types of questions and Section II of conventional papers. Both Sections will cover the entire syllabus of the relevant engineering disciplines viz. Civil Engineering, Mechanical Engineering, Electrical Engineering and Electronics & Telecommunication Engineering. The details of the written Examination i.e. subject, No. of questions, duration and maximum marks allotted to each subject are given below.
Part II— Personality test carrying a maximum of 200 marks of such of the candidates who qualify on the basis of the written examination.
SUCCESS TIPS-
-----------------------------
-Among all the career options available for engineers across domains, i.e. in private, public and government sectors still the best, prestigious and coveted career remains that of esteemed Indian Engineering Services(IES).
-Through Indian Engineering Services (IES) a candidate gets a career in most reputed government departments like Indian Railways, Military Engineering Services, C entral Engineering Services,Telecommunication Department, Central Water Services and other esteemed departments.
-In Indian Engineering Services (IES), an Engineer gets an opportunity to handle technically challenging roles and tasks technically, which have a direct bearing on the building up of infrastructure and services of our nation.
-Strategy for the Engineering Services Examination, The foundation of success can be laid on the resolute efforts but a sound strategy accompanied by never say die spirit makes the recipe of success.
-Success can’t be achieved overnight hence a prudent strategy matters a lot.
-For success in Engineering Services Exam, a candidate is required to have excellent fundamentals in the core subjects, along with thorough update on general awareness, current affairs and no less, all the traits of matured personality.
-Following subsequent points will be worth mentioning and aspirants should necessarily keep a note of the same viz:
-Get acquainted with the latest examination pattern and syllabus of the exam. Go through the previous year's question papers. Compare them and see what types of questions are repeated every year.
-It is advisable not to go refer several books for same topic, instead it is better to refer one good book for each topic, which clarifies basic concepts. Selective books are advisable for selected topics.
-For every candidate time management is very essential along with the setting of target. Johann Wolfgang von Goethe is apt in his words “One always has time enough, if one will apply it well.” 

The first step which every candidate should follow is to make a time table. Take one subject from each section of your technical syllabus and devote at least 3 hours daily to it. Try to devote 1 hour each to English and General Studies so that you can take an edge as it is key differentiator for being in top rankers.
-Manage your time table such that it has good distribution of study hours for General Ability Section and technical papers, as it makes studies enjoyable and it becomes easy to sustain the momentum for longer hours, without boredom setting in and without losing interest and enthusiasm.
-It is always better to prepare short term plan of study, which should be framed in mind and executed.
-While studying the technical subjects don’t forget to make short notes of important topics. Make a separate list of formulae for each subject and revise the short notes and formulae list daily.
-After completion of the topic solve all previous year questions and practice other questions which are available in good books. This will help you to assess yourself for level of understanding of the subject.
-When you are solving the question set the time limit and after the completion of it check whether you have completed the task within stipulated time or not.
-It is better to practice questions on OMR sheets for marking the answers, which will help to practice the marking of correct answers on OMR sheets quickly in the examinations.
-After completion of it take another subject and follow the same guidelines and don’t forget to revise the important portion and your short notes of the subject which you have prepared earlier.
-While preparing the English, segregate the vocabulary from previous 10 years paper of Engineering Services Examination and Combined Defense Services Examination. Try to memorize at least 20 words daily and don’t miss to revise those words.
-The next step to prepare the portion of English is solve daily 10 to 15 questions based on finding errors and rearrangement of sentences.
-From the topics of general studies first of all find out the area of your interest and study it in the form of story or try to correlate the things. It will develop interest and make the things comfortable.

Recommended books for GATE 2016

See if you want to prepare for GATE 2016 which is going to be preapared by IISc so first of all let me tell
Here list of books for preparation.
1. Thermodynamics -- P K Nag.
2. Fluid mechanics -- Bansal/ modi & seth /SOM
(Bansal is simple and upto the mark.. Modi & Seth is good book for clearing concepts.. SOM is good book if you are good in vector mechanics and differentail equation)
3. Heat and mass transfer -- Sachdeva/Holman
(Sachdeva & Holman books are same, fundamentals of Heat and mass transfer by sachdeva is Indian edition of Holman book).
4. SOM -- B.C. Punamia / Timoshenko.
(Punamia is good for both concept and problems... Timoshenko gives full clearity of all concepts but you won't find GATE related problems)
5 . I C engine -- Mathur & Sharma / V Ganeshan
(I used V ganeshan book its good and have sufficient problems... Mathur & sharma is aloso good book i heard it from friend but i never used)
6. Material science -- Narula & Narula / Callister / IP Singh
( Callister is very good but very vast, if you time then refer some times.. Narula & Narula and IP Singh good books for GATE point of view).
7. Theory of Machines and Mechanical vibration– SS Rattan.
8. Machine Design -- Bhandari/ Shigley.
(Bhandari is perfect book for GATE and IES... Shigley is very good book for concept).
9.Refrigeration and Air Conditioning-- P. K Nag /CP Arora Domkundwar
10. Industrial Engg -- O. P. Khanna Buffa & Sarin
(for Industrial Engg i used hand made notes, so i am not sure of how khanna book is, you can take help of others to decide the book)
11. Operational research --- kanti swarup/ SD Sharma.
12.Manufacturing process -- P N Rao Vol 1& 2/ R K Jain/ Hajra & Choudhary/S K mondal notes which is available in major book houses.
Or A text book on Production Engineering- Dr. Swadesh Singh.
( while preparing for MP be little choosy and stick to the syllabus, because as per my knowledge no book will give you complete information, but i am not sure)
13.Mathematics --BS Grewal/Erwin Kreyszig
(Both books are good, if you like maths then go for erwin kerysing book, really good book and vast... or else for simple GATE preparation Grewal; is more than enough)
14.Aptitude -- As a engineers i don't think we need book for GATE aptitude, but still one can refer Agarwal book..
At last prepare GATE previous years of 1984, 1990, 1996, 2002, 2008, 2016 because they were set by IISc Bangalore and the difficulty level will be almost same with the type of questions

Foot Step Bearig Sectioned Assembly

Different types of forces

There are different types of forces that act in different ways on structures such as bridges, chairs, buildings, in fact any structure. The main examples of forces are shown below. Study the diagram and text and then draw a diagram/ pictogram to represent each of these forces. 

A Static Load : A good example of this is a person seen on the left. He is holding a stack of books on his back but he is not moving. The force downwards is STATIC.
A Dynamic Load : A good example of a dynamic load is the person on the right. He is carrying a
weight of books but walking. The force is moving or DYNAMIC.

DYNAMIC LOAD (moving)                                     STATIC LOAD (standing still)

 

Internal Resistance : The person in the diagram is sat on the mono-bicycle and the air filled tyre is under great pressure. The air pressure inside it pushes back against his/her weight. 

INTERNAL RESISTANCE

Tension : The rope is in "tension" as the two people
pull on it. This stretching puts the rope in tension. 

TENSION

Compression : The weight lifter finds that his body
is compressed by the weights he is holding above
his head.

COMPRESSION

 

 Shear Force : A good example of shear force is
seen with a simple scissors. The two handles put
force in different directions on the pin that holds the
two parts together. The force applied to the pin is
called shear force.

                                                                                 SHEAR FORCE

 Torsion : The plastic ruler is twisted between both hands. The ruler is said to be in a state of torsion.
                                                              TORSION

Classifications of FluidTypes of Fluids, Fluids,

Source: Uzochukwu Mike
What are types of Fluids?
Of what types/classifications are fluids in science and engineering study? What do you think is the definition of fluid? Fluids can be defined as substances that flow or deform under the application of shear stress, and these include liquids and gases. They are part of engineering study in many tertiary institutions of the world.
Basically, in the study of science, fluids are divided into two broad groups. These divisions in this write-up are known as types of fluids which are Newtonian and non- Newtonian fluids. Newtonian
fluids are those fluids that obey Newton Law of viscosity. Non-Newtonian fluids are the opposite of
Newtonian fluid in the sense that they do not obey Newton Law of viscosity. Non Newtonian fluids in this text are sub-divided into time-independent, time-dependent and elasticoviscous or viscoelastic
fluids.
Newtonian Fluids
What are Newtonian fluids. Newtonian fluids as written in the introductory part of this text are those fluids that concur (agree) with the Newton Law of viscosity. Viscosity is the opposition to the flow of fluids and it is measured in force per unit area of the fluid. The generally accepted unit of viscosity is Newton per meter square (NM -2 ). This is known as the SI unit of viscosity which is the same with that of stress.
Mathematically, viscosity is expressed as Force per unit area or simply F ̸̸ A. Newton law of viscosity
states that the shear stress on a fluid element layer is directly proportional to the rate of shear strain. In Newtonian fluids, coefficient of viscosity does not change with the rate of deformation of the fluid.
Examples of Newtonian fluids are: water, kerosene and air.It is shown mathematically as: τ = ηγ; where τ = shear stress, η and γ are coefficient of viscosity and share strain respectively.
Non- Newtonian Fluids
What are Non-Newtonian fluids and their classifications?
Non-Newtonian fluids are those fluids that do not obey Newton’s Law. They are the opposite of Newtonian fluids. Examples of non-Newtonian fluids are colloids, emulsions, pastes, sols, gels, thick
slurry, latex-based paints, and Biological fluids. Note that non-Newtonian fluids are many but these are few examples given. Non-Newtonian fluids do not exhibit the property of Newtonian fluids where
shear stress is directly proportional to shear rate.
There are three broad classifications of non- Newtonian fluids. These three classifications are: time-independent, time-dependent and viscoelastic fluids. The viscoelastic fluids can also be called
elasticoviscous fluids. One should not be confused because some textbooks relating to fluids may only one of these two names. Notwithstanding the three broad classifications of non-Newtonian fluids, there are also some other divisions of the three.
Time-Independent Fluids
As the name sounds, time-independent fluids are those non-Newtonian fluids that do not depend on time. They are those fluids in which the shear rate at a given point is a function of stress at that point
only. Examples of time-independent fluids are Casson, Bingham, Dilatent and Pseudoplastic fluid.
The Bingham fluid as an exampleof time-independent fluid does not flow at all until the shear stress exceeds certain critical value called yield stress. In this fluid, the flow behaviors appear like that of Newtonian once the system begins to flow. There is an internal structure in this type of fluid which breaks down before flow of the fluid can start. Notable examples of Bingham fluids are tomato puree, wood pulp suspensions, butter, drilling mud and toothpaste. When equation is used to represent Bingham fluid, it is represented as: τ = τ y + ƞγ , where τ y is yield stress.
Casson fluids also require a critical shear stress to overcome before flow can occur in the system. The
type of flow in this type of time-independent fluid is non-Newtonian, non-linear and parabolic in shape.
Casson and Bingham fluids are called plastic fluids.
Dilatent and Pseudoplastic fluids exhibit different characters on their own. Dilatent fluid is also called
shear thickening fluid. Dilatant fluid becomes more viscous as the shear stress increases. The shear stress increases much more rapidly than the shear rate in this kind of fluid. Examples of dilatent fluids are slurry and highly concentrated suspensions, like, Poly Vinyl Chloride. Pseudoplastic fluid is opposite to Dilatent fluid because the share rate increases much more rapidly than the shear stress.
It is known as shear thinning fluid. As the shear stress increases, pseudoplastic fluid becomes less viscous.
Time-Dependent Fluids
Time-dependent fluids are fluids whose shear rate is a function of shear stress and time. In this type of non-Newtonian fluid, the property of the fluid flow such as apparent viscosity changes with time. It is further classified into thixotropic and rheopectic fluid. In relation of thixotropic with rheopectic fluids, if the shear stress and shear strain relationship are observed with increasing shear rate, both sets of data do not coincide. This results to formation of hysteresis loop. In thixotropic and rheopectic fluids, at a given shear rate; there are two apparent viscosities depending on when the readings were
taken. The difference between the two is that thixotropic fluid becomes less viscous on application of stress while rheopectic fluid becomes more viscous on application of stress.
Elasticoviscous Fluids
Fluids that are predominantly viscous but show partial elastic recovery after deformation are termed elasticoviscous fluids. Examples of such fluids are multi-grade oils, polymer melts and liquid detergents. The term viscoelastic fluid is also used in place of elasticoviscous fluids as the former denotes solids with viscous properties while the later (elasticoviscous) denotes fluids that possess elastic property.
Conclusion
In summary, this write-up has dealt seriously on types of fluids based on science and engineering study. Fluids cannot be done without in our everyday life and this is one of the reasons that makes scientists to show more interesting in categorizing them and for more in-depth study of their flow. One of the basic types of food which people neglect is fluid. Do you know what that important fluid is? It is no other thing but the water we drink on our daily basis and I do not think you can do without it. Gasoline is another basic fluid used in automobiles and this is of great help to man. We cannot be able to power or motors on without this energy supplier. So, respect is to be given to fluids as they contribute to both technological and human development. Fluids were categorized broadly as Newtonian and Newtonian fluids. The non-Newtonian fluids were further divided into other classes and explained in sub-headings.
References
Fluid Mechanics by R.K Rajput;
Introduction to Polymer Technology by Dr. E. M. Katchy.

Classification of Automobiles

An automobile is a vehicle that is capable of propelling itself. Since 17th century, several attempts have been made to design and construct a practically operative automobile. Today, automobiles play crucial role in the social, economic and industrial growth of any country.
After the designing of Internal Combustion Engines, the Automobile industries has seen a tremendous growth.

Classification of Automobiles:
Automobiles can be classified into several types based on many criteria. A brief classification of automobiles is listed below:
1. Based on Purpose :
Passenger vehicles : These vehicles carry passengers. e.g: Buses, Cars, passenger trains.
Goods vehicles: These vehicles carry goods from one place to another place. e.g: Goods lorry, Goods carrier.
Special Purpose : These vehicles include Ambulance, Fire engines, Army Vehicles.
2. Based on Load Capacity: Light duty vehicle : Small motor vehicles. eg: Car, jeep, Scooter, motor cycle
Heavy duty vehicle: large and bulky motor vehicles. e.g: Bus, Truck, Tractor
3. Based on fuel used:
Petrol engine vehicles : Automobiles powered by petrol engine. e.g: scooters, cars, motorcycles.
Diesel engine vehicles : Automobiles powered by diesel engine. e.g: Trucks, Buses, Tractors.
Gas vehicles : Vehicles that use gas turbine as power source. e.g: Turbine powered cars.
Electric vehicles : Automobiles that use electricity as a power source. e.g: Electric cars, electric buses.
Steam Engine vehicles : Automobiles powered by steam engine. e.g: Steamboat, steam locomotive,
steam wagon.
4. Based on Drive of the vehicles:
Left Hand drive : Steering wheel fitted on left hand side.
Right Hand drive : Steering wheel fitted on right hand side.
Fluid drive : Vehicles employing torque converter, fluid fly wheel or hydramatic transmission.
5. Based on number of wheels and axles:
Two wheeler : motor cycles, scooters
Three wheeler : Tempo, auto-rickshaws
Four wheeler : car, Jeep, Bus, truck Six wheeler : Buses and trucks have six tires out of which four are carried on the rear wheels for additional reaction.
Six axle wheeler : Dodge(10 tire) vehicle
6. Based on type of transmission:
Automatic transmission vehicles: Automobiles that are capable of changing gear ratios automatically as they move. e.g: Automatic Transmission Cars.
Manual transmission vehicles: Automobiles whose gear ratios have to be changed manually. Semi-automatic transmission vehicles: Vehicles that facilitate manual gear changing with clutch
pedal.
7. Based on Suspension system used:
Convectional – Leaf Spring
Independent – Coil spring, Torsion bar,
Pneumatic.

Bernoulli’s Principle and Equation

During 17^th century, Daniel Bernoulli investigated the forces present in a moving fluid, derived an equation and named it as an Bernoulli’s Equation. Below image shows one of many forms of Bernoulli’s equation.
The Bernoulli equation gives an approximate equation that is valid only in inviscid regions of flow where net viscous forces are negligibly small compared to inertial, gravitational or pressure forces. Such regions occur outside of boundary layers and waves

The Bernoulli Equation can be considered to be a statement of the conservation of energy principle appropriate for flowing fluids. The qualitative behavior that is usually labeled with the term "Bernoulli effect" is the lowering of fluid pressure in regions where the flow velocity is increased. This lowering of pressure in a constriction of a flow path may seem counterintuitive, but seems less so when you consider pressure to be energy density. In the high velocity flow through the constriction, kinetic energy must increase at the expense of pressure energy.

Steady-state flow caveat: While the Bernoulli equation is stated in terms of universally valid ideas like conservation of energy and the ideas of pressure, kinetic energy and potential energy, its application in the above form is limited to cases of steady flow. For flow through a tube, such flow can be visualized as laminar flow, which is still an idealization, but if the flow is to a good approximation laminar, then the kinetic energy of flow at any point of the fluid can be modeled and calculated. The kinetic energy per unit volume term in the equation is the one which requires strict constraints for the Bernoulli equation to apply - it basically is the assumption that all the kinetic energy of the fluid is contributing directly to the forward flow process of the fluid. That should make it evident that the existence of turbulence or any chaotic fluid motion would involve some kinetic energy which is not contributing to the advancement of the fluid through the tube.
It should also be said that while conservation of energy always applies, this form of parsing out that energy certainly does not describe how that energy is distributed under transient conditions. A good visualization of the Bernoulli effect is the flow through a constriction, but that neat picture does not describe the fluid when you first turn on the flow.
Another approximation involved in the statement of the Bernoulli equation above is the neglect of losses from fluid friction. Idealized laminar flow through a pipe can be modeled by Poiseuille's law, which does include viscous losses resulting in a lowering of the pressure as you progress along the pipe. The statement of the Bernoulli equation above would lead to the expectation that the pressure would return to the value P₁ past the constriction since the radius returns to its original value. This is not the case because of the loss of some energy from the active flow process by friction into disordered molecular motion (thermal energy). More accurate modeling can be done by combining the Bernoulli equation with Poiseuille's law. A real example which might help visualize the process is the pressure monitoring of the flow through a constricted tube.
   

Despite its simplicity, Bernoulli’s Principle has proven to be a very powerful tool in fluid mechanics.
Care must be taken when applying the Bernoulli equation since it is an approximation that applies only to inviscid regions of flow. In general, frictional effects are always important very close to solid walls and directly downstream of bodies.
The motion of a particle and the path it follows are described by the velocity vector as a function of time and space coordinates and the initial position of the particle. When the flow is steady, all particles that pass through the same point follow the same path and the velocity vectors remain tangent to the path at every point.

 

 

 

 

 

During 17^th century, Daniel Bernoulli investigated the forces present in a moving fluid, derived an equation and named it as an Bernoulli’s Equation. Below image shows one of many forms of Bernoulli’s equation.

 

 

The Bernoulli equation gives an approximate equation that is valid only in inviscid regions of flow where net viscous forces are negligibly small compared to inertial, gravitational or pressure forces. Such regions occur outside of boundary layers and waves - See more at: http://www.me-mechanicalengineering.com/bernoullis-principle-and-equation/#sthash.2lIUkDNX.dpuf