Mechanical engineering

Encyclopedia : M : ME : MEC : Mechanical engineering

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Mechanical engineering is a very broad field that involves the application of physical principles for analysis, design, manufacturing, and maintenance of mechanical systems. The process of mechanical engineering 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 can be accomplished with the aid of machines including robots, milling machines, CNCs and lathes.

Other disciplines that overlap with mechanical engineering in one or more areas include aerospace engineering, architectural engineering, chemical engineering, civil engineering, electrical engineering, engineering physics, industrial engineering, nuclear engineering, systems engineering, and many other Fields of engineering.

Development of mechanical engineering

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.

Education

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 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

To become a licensed Practicing Engineer, an engineer must

• pass the Fundamentals of Engineering (FE) exam,
• work a given number of years as an Engineer in Training (EIT),
• pass the PE (Practicing Engineer) exam.

Not every mechanical engineer chooses to become licensed; those that choose to become Practicing Engineers can be distinguished by the post-nominal title 'PE', as in: John Doe, PE. A distinction similar to practicing engineer status is 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

Most mechanical engineering programs offer the same major subjects of study to ensure continued accreditation of the program. Universities 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 and air conditioning,
• fluid mechanics and dynamics,
• robotics (including kinematics and dynamics),
• manufacturing technology,
• 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 2006Harvard 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 such as 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.

Salaries and workforce statistics

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

Subdisciplines

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

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 both elastic and plastic deformation of objects or groups of objects under known forces (also called loads) or stresses, where stress is defined as force per unit area (F/A). Subdisciplines of mechanics include

• Statics, the study of non-moving bodies under known loads
• Dynamics (or kinetics), the study of how forces affect moving (translating or rotating) 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, rather than . It is contrasted by discrete mechanics.

Uses

Mechanical engineers typically use mechanics in the design or analysis phases of engineering. Statics might be employed when designing a structure to evaluate what parts of the structure will bear most of the applied forces. Dynamics might be used when designing an 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 above mentioned structure or engine. Fluid Mechanics might be used to design a ventilation system for the abovementioned structure (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.

Uses

Mechanical 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

Mechatronics is a branch of mechanical engineering, but is also a branch of Electrical Engineering and Software Engineering. Mechatronics 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 and move the laser within the drive, while an optical system reads and interprets the data on the CD and software converts the data to bits.

Uses

Mechatronics 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.

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Robotics

Robotics is an application of mechatronics (above) 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).

Uses

Robots 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).

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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 does not always have to be defined as when a part breaks, however. Failure simply implies that the part did not work as intended. Some systems are designed to break, such as the perforated top sections of some plastic bags. If these systems do not break, failure analysis might be employed to determine the cause.

Uses

Failure 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 . Engineers may use handbooks such as those published by ASM 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.

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Thermodynamics

Thermodynamics is a branch of mechanical engineering, but it is also a branch of Chemical Engineering. Thermodynamics is the study of energy, and how that 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.

Uses

Thermodynamics is used most often in mechanical engineering in the design and analysis of engines and power plants.

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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 Computer-Aided Drafting (CAD) 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 Computer-Aided Manufacturing (CAM) 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 typically be done by a machine.

Uses

Drafting 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).

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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.

Current areas of research in mechanical engineering

Mechanical engineering is not a 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 an 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

References

Format used for web citations: Title - http://link - Notes. Accessed Date.

See also

• List of mechanical engineering topics
• Mechanical engineering technology
• Fields of engineering
• Simple machine
• List of mechanical engineers
• List of inventors
• Patent

Further reading

External links

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