Mechanical engineering
"Mechanical Engineering" redirects here. For the
professional association, see ASME.
Mechanical engineering is the discipline that applies
engineering, physics, and materials science principles to design, analyze,
manufacture, and maintain mechanical systems. It is one of the oldest and
broadest of the engineering disciplines.
The mechanical engineering field requires an understanding
of core areas including mechanics, dynamics, thermodynamics, materials science,
structural analysis, and electricity. In addition to these core principles,
mechanical engineers use tools such as computer-aided design (CAD), and product
life cycle management to design and analyze manufacturing plants, industrial
equipment and machinery, heating and cooling systems, transport systems,
aircraft, watercraft, robotics, medical devices, weapons, and others. It is the
branch of engineering that involves the design, production, and operation of
machinery.
Mechanical engineering emerged as a field during the
Industrial Revolution in Europe in the 18th century; however, its development
can be traced back several thousand years around the world. In the 19th
century, developments in physics led to the development of mechanical
engineering science. The field has continually evolved to incorporate
advancements; today mechanical engineers are pursuing developments in such
areas as composites, mechatronics, and nanotechnology. It also overlaps with
aerospace engineering, metallurgical engineering, civil engineering, electrical
engineering, manufacturing engineering, chemical engineering, industrial
engineering, and other engineering disciplines to varying amounts. Mechanical
engineers may also work in the field of biomedical engineering, specifically
with biomechanics, transport phenomena, biomechatronics, bionanotechnology, and
modeling of biological systems. See glossary of mechanical engineering.
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Archimedes' screw was operated by hand and could efficiently
raise water, as the animated red ball demonstrates
History
The application of mechanical engineering can be seen in the
archives of various ancient and medieval societies. In ancient Greece, the
works of Archimedes (287–212 BC) influenced mechanics in the Western tradition
and Heron of Alexandria (c. 10–70 AD) created the first steam engine
(Aeolipile).[3] In China, Zhang Heng (78–139 AD) improved a water clock and
invented a seismometer, and Ma Jun (200–265 AD) invented a chariot with
differential gears. The medieval Chinese horologist and engineer Su Song
(1020–1101 AD) incorporated an escapement mechanism into his astronomical clock
tower two centuries before escapement devices were found in medieval European
clocks. He also invented the world's first known endless power-transmitting
chain drive.[4]
During the Islamic Golden Age (7th to 15th century), Muslim
inventors made remarkable contributions in the field of mechanical technology.
Al-Jazari, who was one of them, wrote his famous Book of Knowledge of Ingenious
Mechanical Devices in 1206 and presented many mechanical designs. He is also
considered to be the inventor of such mechanical devices which now form the
very basic of mechanisms, such as the crankshaft and camshaft.[5]
During the 17th century, important breakthroughs in the
foundations of mechanical engineering occurred in England. Sir Isaac Newton
formulated Newton's Laws of Motion and developed Calculus, the mathematical
basis of physics. Newton was reluctant to publish his works for years, but he
was finally persuaded to do so by his colleagues, such as Sir Edmond Halley,
much to the benefit of all mankind. Gottfried Wilhelm Leibniz is also credited
with creating Calculus during this time period.
During the early 19th century industrial revolution, machine
tools were developed in England, Germany, and Scotland. This allowed mechanical
engineering to develop as a separate field within engineering. They brought
with them manufacturing machines and the engines to power them.[6] The first
British professional society of mechanical engineers was formed in 1847
Institution of Mechanical Engineers, thirty years after the civil engineers
formed the first such professional society Institution of Civil Engineers.[7]
On the European continent, Johann von Zimmermann (1820–1901) founded the first
factory for grinding machines in Chemnitz, Germany in 1848.
In the United States, the American Society of Mechanical
Engineers (ASME) was formed in 1880, becoming the third such professional
engineering society, after the American Society of Civil Engineers (1852) and
the American Institute of Mining Engineers (1871).[8] 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. Education in mechanical engineering
has historically been based on a strong foundation in mathematics and science
Education
Degrees in mechanical engineering are offered at various
universities worldwide; in Ireland, Brazil, Philippines, Pakistan, China,
Greece, Turkey, North America, South Asia, Nepal, India, Dominican Republic,
Iran and the United Kingdom, mechanical engineering programs typically take
four to five years of study and result in a Bachelor of Engineering (B.Eng. or
B.E.), Bachelor of Science (B.Sc. or B.S.), Bachelor of Science Engineering
(B.Sc.Eng.), Bachelor of Technology (B.Tech.), Bachelor of Mechanical
Engineering (B.M.E.), or Bachelor of Applied Science (B.A.Sc.) degree, in or
with emphasis in mechanical engineering. In Spain, Portugal and most of South
America, where neither B.Sc. nor B.Tech. programs have been adopted, the formal
name for the degree is "Mechanical Engineer", and the course work is
based on five or six years of training. In Italy the course work is based on
five years of education, and training, but in order to qualify as an Engineer
one has to pass a state exam at the end of the course. In Greece, the
coursework is based on a five-year curriculum and the requirement of a
'Diploma' Thesis, which upon completion a 'Diploma' is awarded rather than a
B.Sc.
In Australia, mechanical engineering degrees are awarded as
Bachelor of Engineering (Mechanical) or similar nomenclature[10] although there
are an increasing number of specialisations. The degree takes four years of
full-time study to achieve. To ensure quality in engineering degrees, Engineers
Australia accredits engineering degrees awarded by Australian universities in
accordance with the global Washington Accord. Before the degree can be awarded,
the student must complete at least 3 months of on the job work experience in an
engineering firm. Similar systems are also present in South Africa and are
overseen by the Engineering Council of South Africa (ECSA).
In the United States, most undergraduate mechanical
engineering programs are accredited by the Accreditation Board for Engineering
and Technology (ABET) to ensure similar course requirements and standards among
universities. The ABET web site lists 302 accredited mechanical engineering
programs as of 11 March 2014.[11] Mechanical engineering programs in Canada are
accredited by the Canadian Engineering Accreditation Board (CEAB),[12] and most
other countries offering engineering degrees have similar accreditation
societies.
In India, to become an engineer, one needs to have an
engineering degree like a B.Tech or B.E, have a diploma in engineering, or by
completing a course in an engineering trade like fitter from the Industrial
Training Institute (ITIs) to receive a "ITI Trade Certificate" and
also pass the All India Trade Test (AITT) with an engineering trade conducted
by the National Council of Vocational Training (NCVT) by which one is awarded a
"National Trade Certificate". A similar system is used in Nepal.
Some mechanical engineers go on to pursue a postgraduate
degree such as a Master of Engineering, Master of Technology, Master of
Science, Master of Engineering Management (M.Eng.Mgt. or M.E.M.), a Doctor of
Philosophy in engineering (Eng.D. or Ph.D.) or an engineer's degree. The
master's and engineer's degrees may or may not include research. The Doctor of
Philosophy includes a significant research component and is often viewed as the
entry point to academia.[13] The Engineer's degree exists at a few institutions
at an intermediate level between the master's degree and the doctorate.
Coursework
Standards set by each country's accreditation society are
intended to provide uniformity in fundamental subject material, promote
competence among graduating engineers, and to maintain confidence in the
engineering profession as a whole. Engineering programs in the U.S., for
example, are required by ABET to show that their students can "work
professionally in both thermal and mechanical systems areas."[14] The
specific courses required to graduate, however, may differ from program to
program. Universities and Institutes of technology 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.
The fundamental subjects of mechanical engineering usually include:
Mathematics (in particular, calculus, differential
equations, and linear algebra)
Basic physical sciences (including physics and chemistry)
Statics and dynamics
Strength of materials and solid mechanics
Materials Engineering, Composites
Thermodynamics, heat transfer, energy conversion, and HVAC
Fuels, combustion, Internal combustion engine
Fluid mechanics (including fluid statics and fluid dynamics)
Mechanism and Machine design (including kinematics and
dynamics)
Instrumentation and measurement
Manufacturing engineering, technology, or processes
Vibration, control theory and control engineering
Hydraulics, and pneumatics
Mechatronics, and robotics
Engineering design and product design
Drafting, computer-aided design (CAD) and computer-aided manufacturing
Mechanical engineers are also expected to understand and be
able to apply basic concepts from chemistry, physics, chemical engineering,
civil engineering, and electrical engineering. All mechanical engineering
programs include multiple semesters of mathematical classes including calculus,
and advanced mathematical concepts including differential equations, partial
differential equations, linear algebra, abstract 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 control systems, robotics, transport and logistics,
cryogenics, fuel technology, automotive engineering, biomechanics, vibration,
optics and others, if a separate department does not exist for these subjects.
Most mechanical engineering programs also require varying
amounts of research or community projects to gain practical problem-solving
experience. In the United States it is common for mechanical engineering
students to complete one or more internships while studying, though this is not
typically mandated by the university. Cooperative education is another option.
Future work skills[18] research puts demand on study components that feed
student's creativity and innovation.
License and regulation
Engineers may seek license by a state, provincial, or
national government. The purpose of this process is to ensure that engineers
possess the necessary technical knowledge, real-world experience, and knowledge
of the local legal system to practice engineering at a professional level. Once
certified, the engineer is given the title of Professional Engineer (in the
United States, Canada, Japan, South Korea, Bangladesh and South Africa),
Chartered Engineer (in the United Kingdom, Ireland, India and Zimbabwe),
Chartered Professional Engineer (in Australia and New Zealand) or European
Engineer (much of the European Union), or Professional Engineer in Philippines
and Pakistan.
In the U.S., to become a licensed Professional Engineer
(PE), an engineer must pass the comprehensive FE (Fundamentals of Engineering)
exam, work a minimum of 4 years as an Engineering Intern (EI) or
Engineer-in-Training (EIT), and pass the "Principles and Practice" or
PE (Practicing Engineer or Professional Engineer) exams. The requirements and
steps of this process are set forth by the National Council of Examiners for
Engineering and Surveying (NCEES), a composed of engineering and land surveying
licensing boards representing all U.S. states and territories.
In the UK, current graduates require a BEng plus an
appropriate master's degree or an integrated MEng degree, a minimum of 4 years
post graduate on the job competency development, and a peer reviewed project
report in the candidates specialty area in order to become a Chartered
Mechanical Engineer (CEng, MIMechE) through the Institution of Mechanical
Engineers. CEng MIMechE can also be obtained via an examination route
administered by the City and Guilds of London Institute.
In most developed 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. "Only a
licensed engineer, for instance, may prepare, sign, seal and submit engineering
plans and drawings to a public authority for approval, or to seal engineering
work for public and private clients."[20] This requirement can be written
into state and provincial legislation, such as in the Canadian provinces, for
example the Ontario or Quebec's Engineer Act.
In other countries, such as Australia, and the UK, no such
legislation exists; however, practically all certifying bodies maintain a code
of ethics independent of legislation, that they expect all members to abide by
or risk expulsion.
Further information: FE Exam, Professional Engineer,
Incorporated Engineer, and Washington Accord
Job duties
Mechanical engineers research, design, develop, build, and
test mechanical and thermal devices, including tools, engines, and machines.
Mechanical engineers typically do the following:
Analyze problems to see how mechanical and thermal devices
might help solve the problem.
Design or redesign mechanical and thermal devices using
analysis and computer-aided design.
Develop and test prototypes of devices they design.
Analyze the test results and change the design as needed.
Oversee the manufacturing process for the device.
Mechanical engineers design and oversee the manufacturing of
many products ranging from medical devices to new batteries. They also design
power-producing machines such as electric generators, internal combustion
engines, and steam and gas turbines as well as power-using machines, such as
refrigeration and air-conditioning systems.
Like other engineers, mechanical engineers use computers to
help create and analyze designs, run simulations and test how a machine is
likely to work.
Salaries and workforce statistics
The total number of engineers employed in the U.S. in 2015
was roughly 1.6 million. Of these, 278,340 were mechanical engineers (17.28%),
the largest discipline by size.[24] In 2012, the median annual income of
mechanical engineers in the U.S. workforce was $80,580. The median income was
highest when working for the government ($92,030), and lowest in education
($57,090).[25] In 2014, the total number of mechanical engineering jobs was
projected to grow 5% over the next decade.[26] As of 2009, the average starting
salary was $58,800 with a bachelor's degree
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