Mechanical engineering
|
The supertanker AbQaiq - Mech. engineers design vehicles of all sizes. |
Mechanical engineering is a very broad field that involves the application of
physical principles for
analysis,
design,
manufacturing, and maintenance of
mechanical systems. It is made up of a number of subdisciplines concerned with the
mechanics,
kinematics (movement), and
energy of physical objects. Practitioners of mechanical engineering, known as
mechanical engineers, use principles such as heat, force, and the conservation of mass and energy in contributing to the design of vehicles and aircraft, heating & cooling systems, buildings and bridges, industrial equipment and machinery, and much more.
The
process of mechanical engineering is
optimization: engineers strive to optimize the cost, ease, durability, safety, and overall usefulness of objects. This process can be as simple as the design of a chair for comfort or as complex as the optimization of a turbocharged engine for speed. It can be as small as the cutting of a nano-sized gear or as large as the assembly of a supertanker used to carry oil around the world.
Modern analysis and design processes in mechanical engineering are aided by various computational tools including
FEA,
CFD, and
CAD/
CAM. Manufacturing is accomplished with the aid of machines including
robots,
milling machines,
CNCs and
lathes.
Pre-Industrial Revolution, most engineering was restricted to military and civil uses. Engineers in the military, though not always referred to as such, designed fortification systems and various war machines. Civil engineers were responsible primarily for structures. "During the early 19th century in
England mechanical engineering developed as a separate field to provide manufacturing machines and the engines to power them. The first British professional society of civil engineers was formed in 1818; that for mechanical engineers followed in 1847." In the
United States, the first mechanical engineering professional society was formed in 1880, making it the third oldest type of engineering behind civil (1852) and mining & metallurgical (1871). "The first schools in the United States to offer an engineering education were the
United States Military Academy in 1817, an institution now known as
Norwich University in 1819, and
Rensselaer Polytechnic Institute in 1825. An engineering education is based on a strong foundation in mathematics and science; this is followed by courses emphasizing the application of this knowledge to a specific field and studies in the social sciences and humanities to give the engineer a broader education."
[Answers.com Engineering Article - http://www.answers.com/topic/engineering - This article references: the Engineering article in The Columbia Electronic Encyclopedia, Sixth Edition Copyright © 2003, Columbia University Press. ]A Bachelor of Arts (BA) or Bachelor of Science (BS) degree in mechanical engineering is offered at many universities in the United States, and similar programs are offered at universities in most
industrialized nations. In the U.S., mechanical engineering programs typically take four to five years and result in a B.S.M.E./B.A.M.E., or
Bachelor of Science/Arts in Mechanical Engineering. Most mechanical engineering programs are
accredited nationally by
ABET to ensure similar course requirements and standards between universities. The ABET website [
1] lists 276 accredited mechanical engineering programs as of
June 19,
2006.
[ABET searchable database of accredited engineering programs - http://www.abet.org/accrediteac.asp - Accessed June 19, 2006]Some mechanical engineers go on to pursue a postgraduate degree such as a
Master of Engineering/
Master of Science, a Master of Engineering Management, a
Doctor of Philosophy in Engineering or an
Engineer's degree. The Master and Engineer's degree may consist of either
research,
coursework or a mixture of the two. The
Doctor of Philosophy consists of a significant research component and is often viewed as the entry point to
academia.
[Types of post-graduate degrees offered at MIT - http://www-me.mit.edu/GradProgram/GradDegrees.htm - Accessed 19 June 2006]After being awarded a degree, engineers may seek
licensure by a state government. To become a licensed
Practicing Engineer, an engineer must
*pass the comprehensive
FE (Fundamentals of Engineering) exam,
*work a given number of years as an
Engineer in Training (EIT),
*pass the
PE (Practicing Engineer) exam. The purpose of this process is to ensure that engineers possess the necessary technical knowledge and real-world experience to engineer safely. Not every mechanical engineer chooses to become licensed; those that do can be distinguished as Practicing Engineers by the
post-nominal title 'PE', as in:
Jane Doe, PE. A distinction similar to practicing engineer status is the
Chartered Engineer ('CEng') status awarded by some European, Asian and Oceanic engineering organizations. "In most modern countries, certain engineering tasks, such as the design of bridges, electric power plants, and chemical plants, must be approved by a Professional Engineer or a Chartered Engineer."
[Wikipedia, Engineer article - http://en.wikipedia.org/wiki/Engineer - Accessed 19 June 2006]::(See Also:
FE Exam |
Practicing Engineer |
Chartered Engineer)
Mechanical engineering coursework
American Universities offering
accredited programs in mechanical engineering are required to offer several major subjects of study, as determined by
ABET. This is to ensure a minimum level of competence among graduating engineers and to inspire confidence in the engineering profession as a whole. The specific courses required to graduate, however, differ from program to program. Universities will often combine multiple subjects into a single class or split a subject into multiple classes, depending on the faculty available and the University's major area(s) of research. Fundamental subjects of mechanical engineering typically include:
*
statics and
dynamics*
strength of materials*
solid mechanics,
*
instrumentation and
measurement,
*
thermodynamics,
heat transfer,
energy conversion, and
refrigeration / air conditioning,
*
fluid mechanics and
dynamics,
*
mechanism design (including
kinematics and
dynamics),
*manufacturing technology or processes,
*engineering
design,
*
mechatronics and/or
control theory,
*
drafting or
CAD/
CAM.
[University of Tulsa Required ME Courses - http://www.me.utulsa.edu/Undergraduate.html - Accessed 19 June 2006][Harvard Mechanical Engineering Page - http://www.deas.harvard.edu/undergradstudy/engineeringsciences/mechanical/index.html - Accessed 19 June 2006]Mechanical engineers are also expected to understand and be able to apply basic concepts from chemistry, chemical engineering, electrical engineering, and physics. Most mechanical engineering programs include several semesters of
calculus, as well as advanced mathematical concepts which may include
differential equations and
partial differential equations,
linear and
modern algebra, and
differential geometry, among others.
In addition to the core mechanical engineering curriculum, many mechanical engineering programs offer more specialized programs and classes, such as
mechatronics /
robotics,
transport and
logistics,
cryogenics,
fuel technology,
automotive engineering,
biomechanics,
vibration,
optics and others, if a separate department does not exist for these subjects.
[MIT Engineering Electives - http://www-me.mit.edu/UGradProgram/MERequirements.htm Accessed 19 June 2006]Most mechanical engineering programs also require varying amounts of research or community projects to gain practical problem-solving experience. Mechanical engineering students usually hold one or more
internships while studying, though this is not typically mandated by the university.
The total number of engineers employed in the U.S. in 2004 was roughly 1.4 million. Of these, 226,000 were mechanical engineers (15.6%), second only in size to civil engineers at 237,000 (16.4%). The total number of mechanical engineering jobs in 2004 was projected to grow 9 to 17%, with average starting salaries being $50,236 with a bachelors degree, $59,880 with a masters degree, and $68,299 with a doctorate degree. This places mechanical engineering at 8th of 14 among engineering bachelors degrees, 4th of 11 among masters degrees, and 6th of 7 among doctorate degrees in average annual salary.
[U.S. Department of Labor, Bureau of Labor Statistics, Engineering - http://www.bls.gov/oco/ocos027.htm#earnings - Accessed 19 June 2006] The median annual earning of mechanical engineers in the U.S. workforce is roughly $63,000. This number is highest when working for the government ($72,500), and lowest when doing general purpose machinery manufacturing in the private sector ($55,850).
[http://www.worldwidelearn.com/online-education-guide/engineering/mechanical-engineering-major.htm - Website cites NACE and Dept. of Labor as sources, but was unable to verify. Accessed 19 June 2006]Canadian engineers make an average of $28.10 per hour with 3% unemployed. The average for all occupations is $16.91 per hour with 5% unemployed. Eight percent of these engineers are self-employed, and since 1994 the proportion of female engineers has remained constant at 4%.
[http://www.jobfutures.ca/noc/2132p4.shtml - Accessed June 19, 2006]The field of mechanical engineering can be thought of as a collection of many mechanical disciplines. Several of these subdisciplines which are typically taught at the
undergraduate level are listed below, with a brief explanation and the most common application of each. Some of these subdisciplines are unique to mechanical engineering, while others belong to mechanical engineering and one or more other disciplines. Most work that a mechanical engineer does uses skills and techniques from several of these subdisciplines, as well as specialized subdisciplines. Specialized subdisciplines as defined here are usually the subject of
graduate more than undergraduate research. Several specialized subdisciplines are discussed at the end of this section
Mechanics
|
Mohr's circle, a common tool to study stresses in a mechanical element |
Mechanics is, in the most general sense, the study of
forces and their effect upon
matter. Typically, engineering mechanics is used to analyze and predict the acceleration and deformation (both
elastic and
plastic) of objects under known
forces (also called
loads) or
stresses. Subdisciplines of mechanics include
*
Statics, the study of non-moving bodies under known loads
*
Dynamics (or
kinetics), the study of how forces affect moving bodies
*
Mechanics of materials, the study of how different
materials deform under various types of stress
*
Fluid Mechanics, the study of how fluids react to forces. Note that fluid mechanics can be further split into
fluid statics and
fluid dynamics, and is itself a subdiscipline of
continuum mechanics. The application of fluid mechanics in engineering is called
hydraulics.
*
Continuum mechanics is a method of applying mechanics that assumes that objects are continuous. It is contrasted by
discrete mechanics.
UsesMechanical engineers typically use mechanics in the
design or
analysis phases of engineering. If the engineering project were the design of a vehicle,
statics might be employed to design the frame of the vehicle, to evaluate where the stresses will be most intense.
Dynamics might be used when designing the car's engine, to evaluate the forces in the
pistons and
cams as the engine cycles.
Mechanics of materials might be used to choose an appropriate material for the frame or engine.
Fluid mechanics might be used to design a ventilation system for the vehicle (see
HVAC), or to design the
intake system for the engine.
Kinematics
Kinematics is the study of the motion of bodies and systems, while ignoring the forces that cause the motion. The movement of a crane and the oscillations of a piston in an engine are both simple kinematic systems. The crane is a type of
open kinematic chain, while the piston is part of a
closed four bar linkage.
UsesMechanical engineers typically use kinematics in the design and analysis of
mechanisms. Kinematics can be used to find the possible range of motion for a given mechanism, or, working in reverse, can be used to design a mechanism that has a desired range of motion.
Mechatronics & Robotics
Mechatronics is an interdisplinary branch of mechanical engineering,
electrical engineering and
software engineering that is concerned with integrating electrical and mechanical engineering to create
hybrid systems. In this way, machines can be automated through the use of
electric motors,
servo-mechanisms, and other electrical systems in conjunction with special software. A common example of a mechatronics system is a CD-ROM drive. Mechanical systems open and close the drive, spin the CD and move the laser, while an optical system reads the data on the CD and converts it to
bits. Integrated software controls the process and communicates the contents of the CD to the computer.
UsesMechatronics is currently used in the following areas of engineering:
*
Automation, and in the area of
robotics.
*
Servo-Mechanics*
Sensing and
Control Systems*
Automotive engineering, in the design of subsystems such as
anti-lock braking systems
*
Computer engineering, in the design of mechanisms such as hard drives, CD-ROM drives, etc.
|
Industrial robots perform repetitive tasks, such as assembling vehicles. |
Robotics is the application of mechatronics to create
robots, which perform tasks that are dangerous, unpleasant, or repetitive. These robots may be of any shape and size, but all are a) preprogrammed and b) interact physically with the world. To create a robot, an engineer typically employs kinematics (to determine the robot's range of motion) and mechanics (to determine the
stresses within the robot).
UsesRobots are used extensively in
Industrial engineering. They allow businesses to save money on labor and perform tasks that are either too dangerous or too precise for humans to perform them economically. Many companies employ
assembly lines of robots, and some factories are so reboticized that they can run
by themselves. Outside the factory, robots have been employed in bomb disposal,
space exploration, and many other fields. Robots are also sold residentially (see
Roomba).
Structural failure analysis
Structural failure analysis or just
failure analysis is the branch of mechanical engineering devoted to examining not only
why but
how objects break or otherwise fail. Structural failures occur in two modes:
static failure and
fatigue failure. Static structural failure occurs when, upon being
loaded (having a force applied) the object being analyzed either breaks or is deformed
plastically, depending on the criterion for failure. Fatigue failure occurs when an object fails after a number of
cycles, or repeated loadings and unloadings. Fatigue failure occurs because of
imperfections in the object. A microscopic crack on the surface of the object is one type of imperfection, and it will grow slightly with each cycle until the crack is large enough to cause failure.
Failure is not defined as when a part breaks, however; it is defined as when a part does not operate as intended. Some systems, such as the perforated top sections of some plastic bags, are designed to break. If these systems
do not break, failure analysis might be employed to determine the cause.
UsesFailure analysis is often used by mechanical engineers
after a failure has occurred, or while performing maintenance. This differs from the other subdisciplines of mechanical engineering, which are generally employed
before any parts have been
fabricated. Engineers may use handbooks such as those published by ASM [
2] to aid them in determining the type of failure and possible causes.
Failure analysis may be used both in the field, to analyze failed parts, and in laboratories, where parts might undergo controlled failure tests.
Thermodynamics and thermo-science
Thermodynamics is a branch of both mechanical engineering and
Chemical Engineering. At its simplest, thermodynamics is the study of how energy moves through a
system. Typically, engineering thermodynamics is concerned with changing energy from one form to another. Engines, for instance, change
enthalpy, the stored energy in molecules, into
heat and then into
mechanical work that eventually turns the wheels.
UsesThermodynamics principles are used by mechanical engineers in the fields of
heat transfer,
thermofluids, and
energy conversion. Mechanical engineers use thermo-science to design
engines and
power plants, heating, ventilation, and air-conditioning (
HVAC) systems,
heat exchangers,
heat sinks,
radiators,
refrigeration,
insulation, and others.
Drafting
Drafting or
technical drawing is the mean by which mechanical engineers create instructions for
manufacturing parts. A technical drawing can be a computer model or hard-drawn schematic showing the all dimensions necessary to manufacture a part, as well as assembly notes, a list of required materials, and other pertinent information. A U.S. mechanical engineer or skilled worker who creates technical drawings may be referred to as a
drafter or
draftsman (or, more correctly,
draftsperson). Drafting has historically been a two-dimensional process, but recent programs have begun to allow the designer to create in three dimensions.
Instructions for manufacturing a part must be fed to the necessary machinery, either manually, through programmed instructions, or through the use of a or combined CAD/CAM program. Optionally, an engineer may also manually manufacture a part using the technical drawings, but this is becoming an increasing rarity, except in the areas of applied
spray coatings, finishes, and other processes that cannot economically be done by a machine.
UsesDrafting is used in nearly every subdiscipline of mechanical engineering, and by many other branches of engineering and architecture. Three-dimensional models created using CAD software are also commonly used in
Finite element analysis (FEA) and
Computational fluid dynamics (CFD).
List of specialized subdisciplines
The following is a list of some additional subdisciplines and topics within mechanical engineering. These topics may be considered
specialized because they are not typically part of undergraduate mechanical engineering requirements, or require training beyond an undergraduate level to be useful.
*
Acoustics*
Alternative Energy*
Automotive Engineering*
Biomedical Engineering*
Computer-Aided Engineering*
Heating, Ventilation, and Air Conditioning (HVAC)*
Nanotechnology*
Nuclear Engineering*
Piping*
Power Generation*Engineering Based
Programming*
Robotics*Robotics is also listed as a general subdiscipline, but because of the breadth of the subject it may require many years of advanced training to be useful to a particular field.
Mechanical engineering is not a
static field of engineering. Mechanical engineers are constantly pushing the boundaries of what is physically possible in order to produce safer, cheaper, and more efficient machines and mechanical systems. Some technologies at the cutting edge of mechanical engineering are listed below (see also
exploratory engineering).
Nanotechnology
At the smallest scales, mechanical engineering becomes
nanotechnology and
molecular engineering - one speculative goal of which is to create a
molecular assembler to build molecules and materials via
mechanosynthesis. For now this goal remains within
exploratory engineering.
Nuclear fusion
Most nuclear power plants today work on the principle of
nuclear fission. An international effort is currently underway to explore the potential of
nuclear fusion as a cleaner alternative energy source, and an experimental 500 MW power plant known as
ITER is currently under construction in France.
[BBC News report on ITER - http://news.bbc.co.uk/1/hi/sci/tech/4629239.stm - Accessed 19 June 2006]Format used for web citations:Title - http://link - Notes. Accessed
Date.
*
List of mechanical engineering topics*
Mechanical engineering technology*
Fields of engineering*
Simple machine*
List of mechanical engineers*
List of inventors*
Patent*
Engineering Thermodynamics*
Solid Mechanics*
Experimental Heat Transfer[3]*
Heat Transfer Engineering[4]* ''International Journal for Computational Methods in Engineering Science and Mechanics [
5]
* International Journal of Optomechatronics[
6]
* Machining Science and Technology[
7]
* Materials and Manufacturing Processes[
8]
* Mechanics Based Design of Structures and Machines[
9]
* Mechanics of Advanced Materials and Structures[
10]
* Nanoscale and Microscale Thermophysical Engineering[
11]
* Numerical Heat Transfer, Part A[
12]
* Numerical Heat Transfer, Part B[
13]
* Tribology Transactions[
14]''
