In this
introductory chapter, we describe who mechanical engineers are, what they do,
what their challenges and rewards are, what their global impact can be, and
what their notable accomplishments have been. Engineering is the practical
endeavor in which the tools of mathematics and science are applied to develop
cost-effective solutions to the technological problems facing our society.
Engineers design many of the consumer products that you use every day. They
also create a large number of other products that you do not necessarily see or
hear about because they are used in business and industrial settings.
Nevertheless, they make important contributions to our society, our world, and
our planet. Engineers develop the machinery that is needed to manufacture most
products, the factories that make them, and the quality control systems that
guarantee the product’s safety and performance. Engineering is all about making
useful things that work and impact lives.
What is mechanical engineering?
Mechanical
engineering is a branch of engineering that focuses on the design,
construction, and operation of machinery and tools. It involves the application
of principles of physics, materials science, and engineering to the design,
manufacture, and operation of machines and tools. Mechanical engineers use
their knowledge of mathematics, science, and engineering to design, develop,
and test machines, tools, and other mechanical systems.
WHAT IS ENGINEERING?
The word
“engineering” derives from the Latin root ingenuine, meaning to design or to
devise, which also forms the basis of the word “ingenious.” Those meanings are
quite appropriate summaries of the traits of a good engineer. At the most
fundamental level, engineers apply their knowledge of mathematics, science, and
materials as well as their skills in communications and business to develop new
and better technologies. Rather than experiment solely through trial and error,
engineers are educated to use mathematics, scientific c principles, and
computer simulations as tools to create faster, more accurate, and more
economical designs. In that sense, the work of an engineer differs from that of
a scientist, who would normally emphasize the discovery of physical laws rather
than apply those phenomena to develop new products. Engineering is essentially
a bridge between scientific discovery and product applications.
Engineering
does not exist for the sake of furthering or applying mathematics, science, and
computation by themselves. Rather, engineering is a driver of social and
economic growth and an integral part of the business cycle. With that
perspective, the Engineers apply the theories and principles of science and
mathematics to research and develop economical solutions to technical problems.
Their work is the link between perceived social needs and commercial applications.
Engineers design products, machinery to build those products, plants in which
those products are made, and the systems that ensure the quality of the
products and the efficiency of the workforce and manufacturing process.
Engineers design, plan, and supervise the construction of buildings, highways,
and transit systems. They develop and implement improved ways to extract,
process, and use raw materials, such as petroleum and natural gas. They develop
new materials that both improve the performance of products and take advantage
of advances in technology. They harness the power of the sun, the Earth, atoms,
and electricity for use in supplying the Nation’s power needs, and create
millions of products using power. They analyze the impact of the products they
develop or the systems they design on the environment and on people using them.
Engineering knowledge is applied to improving many things, including the
quality of healthcare, the safety of food products, and the operation of
financial systems.
Of the 13
major industry sectors, engineering was the most popular major for CEOs in nine
of them:
• Business
services
• Chemicals
• Communications
• Electricity, gas, and sanitary
• Electronic components
• Industrial and commercial machinery
• Measuring instruments
• Oil and gas extraction
• Transportation equipment
The Elements of Mechanical Engineering
The
discipline of mechanical engineering is concerned in part with certain
“elements”:
• Design
• Professional Practices
• Forces
• Materials
• Fluids
• Energy
• Motion
Mechanical
engineers invent machines and structures that exploit those elements in order
to serve a useful purpose and solve a problem. Original design and the
practical issue of making something that works are the themes behind any
engineering endeavor. An engineer creates a machine or product to help someone
solve a technical problem. The engineer might start from a blank sheet of
paper, conceive something new, develop and refi ne it so that it works reliably,
and all the while satisfy the constraints of safety, cost, and
manufacturability. Robotic welding systems, internal combustion engines, sports
equipment, computer hard disk drives, prosthetic limbs, automobiles, aircraft,
jet engines, surgical tools, and wind turbines are some of the thousands of
technologies that mechanical engineering encompasses. It would not be much of
an exaggeration to claim that, for every product you can imagine, a mechanical
engineer was involved at some point in its design, materials selection,
temperature control, quality assurance, or production. Even if a mechanical
engineer didn’t conceive or design the product per se, it’s still a safe bet
that a mechanical engineer designed the machines that built, tested, or
delivered the product. Mechanical engineering has been defined as the
profession in which power producing and power-consuming machines are
researched, designed, and manufactured. In fact, mechanical engineers devise
machines that produce or consume power over the remarkably wide scale.
WHO ARE MECHANICAL ENGINEERS?
The field
of mechanical engineering encompasses the properties of forces, materials,
energy, fluids, and motion, as well as the application of those elements to
devise products that advance society and improve people’s lives. The U.S.
Department of Labor describes the profession as follows:
Mechanical
engineers research, develop, design, manufacture and test tools, engines,
machines, and other mechanical devices. They work on power-producing machines
such as electricity-producing generators, internal combustion engines, steam
and gas turbines, and jet and rocket engines. They also develop powerusing
machines such as refrigeration and air conditioning equipment, robots used in
manufacturing, machine tools, materials handling systems, and industrial
production equipment.
Mechanical
engineers are known for their broad scope of expertise and for working on a
wide range of machines. Just a few examples include the microelectromechanical
acceleration sensors used in automobile air bags; heating, ventilation, and
air-conditioning systems in office buildings; heavy off-road construction
equipment; hybrid gas-electric vehicles; gears, bearings, and other machine
components; artificial hip implants; deep-sea research vessels; robotic
manufacturing systems; replacement heart valves; noninvasive equipment for
detecting explosives; and interplanetary exploration spacecraft.
Mechanical Engineering’s Top Ten Achievements
Mechanical
engineering isn’t all about numbers, calculations, computers, gears, and
grease. At its heart, the profession is driven by the desire to advance society
through technology. The American Society of Mechanical Engineers (ASME)
surveyed its members to identify the major accomplishments of mechanical
engineers. This professional society is the primary organization that
represents and serves the mechanical engineering community in the United States
and internationally. This top ten list of achievements, summarized, can help
you better understand who mechanical engineers are and appreciate the
contributions they have made to your world. In descending order of the
accomplishment’s perceived impact on society, the following milestones were
recognized in the survey:
Top Ten Achievements of the Mechanical Engineering Profession Compiled by the American Society of Mechanical Engineers
The automobile.
The
development and commercialization of the automobile were judged as the
profession’s most significant achievement in the twentieth century. Two factors
responsible for the growth of automotive technology have been high-power,
lightweight engines and efficient processes for mass manufacturing. German
engineer Nicolaus Otto is credited with designing the first practical
four-stroke internal-combustion engine. After untold effort by engineers, it is
today the power source of choice for most automobiles. In addition to engine
improvements, competition in the automobile market has led to advances in the
areas of safety, fuel economy, comfort, and emission control. Some of the newer
technologies include hybrid gas-electric vehicles, antilock brakes, run-flat
tires, air bags, widespread use of composite materials, computer control of
fuel injection systems, satellite-based navigation systems, variable valve
timing, and fuel cells.
Having
spawned jobs in the machine tool, raw materials, and service industries, the
automobile has grown to become a key component of the world’s economy. From
minivans to stock car racing to Saturday night cruising, the automobile one of
the key contributions of mechanical engineering has had a ubiquitous influence
on our society and culture.
The Apollo program.
In 1961,
President John F. Kennedy challenged the United States to land a man on the
Moon and return him safely to Earth. The first portion of that objective was
realized fewer than ten years later with the July 20, 1969 landing of Apollo 11
on the lunar surface. The three-man crew of Neil Armstrong, Michael Collins,
and Buzz Aldrin returned safely several days later. Because of its
technological advances and profound cultural impact, the Apollo program was
chosen as the second most influential achievement of the twentieth century The
Apollo program was based on three primary engineering developments: the huge
three-stage Saturn V launch vehicle that produced some 7.5 million pounds of
thrust at liftoff, the command and service module, and the lunar excursion
module, which was the first vehicle ever designed to be flown only in space.
It’s stunning to put the rapid pace of Apollo’s development in perspective.
Only 66 years after Wilbur and Orville Wright made their first powered flight,
millions of people around the world witnessed the first lunar landing live on
television.
The Apollo
program is perhaps unique among engineering achievements in the way that it
combined technological advances, the spirit of exploration, and patriotism.
Indeed, the photographs of Earth that have been taken from the perspective of
space have changed how we view ourselves and our planet. Apollo, planetary
exploration, communications satellites, and even sophisticated weather
forecasting would have been impossible without the initiative and dedicated
effort of thousands of mechanical engineers.
Power generation.
One aspect
of mechanical engineering involves designing machinery that can convert energy
from one form to another. Abundant and inexpensive energy is recognized as an
important factor behind economic growth and prosperity, and the generation of
electrical power is recognized as having improved the standard of living for
billions of people across the globe. In the twentieth century, entire societies
changed as electricity was produced and routed to homes, businesses, and
factories. Although mechanical engineers are credited with having developed
efficient technologies to convert various forms of stored energy into more
easily distributed electricity, the challenge to bring power to every man,
woman, and child around the globe still looms for mechanical engineers.
Mechanical engineers manipulate the stored
chemical energy of such fuels as coal, natural gas, and oil; the kinetic energy
of wind that drives electricity-producing turbines; the nuclear energy in
electrical plants, ships, submarines, and spacecraft; and the potential energy of
water reservoirs that feed hydroelectric power plants. Some of the issues that
factor into power generation are the cost of the fuel, the cost of constructing
the power plant, the potential emissions and environmental impact, around the-clock
reliability, and safety. The large-scale generation of electrical power is a
prime example of the need for engineers to balance technology, social,
environmental, and economic considerations. As the supply of natural resources
diminishes and as fuels become more expensive in terms of both cost and the
environment, mechanical engineers will become even more involved in developing
advanced power-generation technologies, including solar, ocean, and wind power
systems.
Agricultural mechanization.
Mechanical engineers have developed technologies to improve significantly the efficiency in the agricultural industry. Automation began in earnest with the introduction of powered tractors in 1916 and the development of the combine, which greatly simplified harvesting grain.
Decades later, research is underway to develop the
capability for machines to harvest a field autonomously, without any human
intervention using advanced machinery, GPS technology, and intelligent guidance
and control algorithms. Other advances include improved weather observation and
prediction, high-capacity irrigation pumps, automated milking machines, and the
digital management of crops and the control of pests. As those technologies
became widespread, people began to take advantage of social, employment, and
intellectual opportunities in sectors of the economy other than agriculture.
The technology of agricultural mechanization enabled many other advances in
other economic sectors including shipping, trade, food and beverage, and
healthcare.
The airplane.
The development of the airplane and related technologies for safe powered flight were also recognized by the American Society of Mechanical Engineers as a key achievement of the profession. Commercial passenger aviation has created travel opportunities for business and recreational purposes, and international travel in particular has made the world become a smaller and more interconnected place Mechanical engineers have developed or contributed to nearly every aspect of aviation technology. One of the main contributions has been in the area of propulsion.
Early airplanes were powered by piston-driven internal-combustion
engines, such as the 12-horsepower engine that was used in the first Wright
Flyer. By contrast, the General Electric Corporation’s engines that power some
Boeing 777 jetliners can develop a maximum thrust of over 100,000 pounds-force.
Advancements in high-performance military aircraft include vectored turbofan
engines that enable the pilot to redirect the engine’s thrust for vertical
takeoffs and landings. Mechanical engineers design the combustion systems,
turbines, and control systems of such advanced jet engines. By taking advantage
of testing facilities such as wind Tunnels, they have also spearheaded the
design of turbines, development of control systems, and discovery of
lightweight aerospace-grade materials, including titanium alloys and graphite fiber
reinforced epoxy composites.
Integrated-circuit mass production.
The
electronics industry has developed remarkable technologies for miniaturizing
integrated circuits, computer memory chips, and microprocessors. The mechanical
engineering profession made key contributions during the twentieth century to
the manufacturing methods involved in producing integrated circuits. While the
vintage 8008 processor that was first sold by the Intel Corporation in 1972 had
2500 transistors, the current Tukwila processor from Intel has over 2 billion
transistors. This exponential rate of growth in the number of components that
can be assembled on a silicon chip is often referred to as Moore’s law, named
after Intel’s cofounder Gordon Moore. Based on past developments, this
observation states that the number of transistors that can be placed on integrated
circuits is expected to double every 18 months. That prediction was made in
1965, and it still holds true, although engineers and scientists are
increasingly pushing up against fundamental physical limits. Mechanical
engineers design the machinery, alignment systems, advanced materials, temperature
control, and vibration isolation that enable integrated circuits to be made at
the nanometer scale. The same manufacturing technology can be used to produce
other machines at the micro or nano level. Using these techniques, machines
with moving parts can be made so small that they are imperceptible to the human
eye and can be viewed only under a microscope. Individual gears can be
fabricated and assembled into geartrains that are no bigger than a speck of
pollen.
Air conditioning and refrigeration.
Mechanical engineers invented the technologies of efficient air conditioning and refrigeration. Today, these systems not only keep people safe and comfortable, but also preserve food and medical supplies in refrigeration systems. Like other infrastructures, we typically do not recognize the value of air conditioning until it is gone. In a record European heat wave during the summer of 2003, for instance, over 10,000 people many elderly died in France as a direct result of the searing temperatures.
Mechanical engineers apply the
principles of heat transfer and energy conversion to design refrigeration
systems that preserve and store food at its source, during transportation, and
in the home. We regularly purchase food that was grown thousands of miles away,
perhaps even in a different country, with confidence that it is fresh. Although
mechanical refrigeration systems had been available as early as the 1880s,
their application was limited to commercial breweries, meat-packing houses,
ice-making plants, and the dairy industry. Those early refrigeration systems
required significant amounts of maintenance, and they were also prone to
leaking hazardous or flammable chemicals, rendering them inappropriate for use
in a home. The development of the refrigerant Freon in 1930 was a major turning
point for the commercialization of safe residential refrigeration and air
conditioning.
Computer-aided engineering technology.
The term
“computer-aided engineering” (CAE) refers to a wide range of automation
technologies in mechanical engineering, and it encompasses the use of computers
for performing calculations, preparing technical drawings, simulating
performance, and controlling machine tools in a factory. Over the past several
decades, computing and information technologies have changed the manner in
which mechanical engineering is practiced. Most mechanical engineers have
access to advanced computer-aided design and analysis software, information
databases, and computer-controlled prototyping equipment.
In some
industries, these CAE technologies have replaced traditional paper-based design
and analysis methods. In large multinational corporations, design teams and
technical information are distributed around the world, and computer networks
are used to design products 24 hours a day. As an example, the Boeing 777 was
the first commercial airliner to be developed through a paperless
computer-aided design process. The 777’s design began in the early 1990s, and a
new computer infrastructure had to be created specifically for the design
engineers.
Conventional
paper-and-pencil drafting services were nearly eliminated. Computer-aided
design, analysis, and manufacturing activities were integrated across some 200
design teams that were spread over 17 time zones. Because the plane had over 3
million individual components, making everything fi t together was a remarkable
challenge. Through the extensive usage of CAE tools, designers were able to
check part-to-part fits in a virtual, simulated environment before any hardware
was produced. By constructing and testing fewer physical mock-ups and
prototypes, the aircraft was brought to market more quickly and more
economically than would have otherwise been possible. Current CAE tools are
being developed for diverse computing platforms including leveraging mobile
devices, cloud computing technologies, and virtual machines.
Bioengineering.
The discipline of bioengineering links traditional engineering fi elds with the life sciences and medicine. Engineering principles, analysis tools, and design methods are applied to solve problems that occur in biological systems. Although bioengineering is considered an emerging fi eld, it ranked in the American Society of Mechanical Engineer’s top ten list not only for the advances that have already been made, but also for its future potential in addressing medical and health-related problems.
One objective of bioengineering
is to create technologies to expand the pharmaceutical and healthcare
industries, including drug discovery, genomics, ultrasonic imaging, artificial
joint replacements, cardiac pacemakers, artificial heart valves, robotically
assisted surgery, and laser surgery. For instance, mechanical engineers apply
the principles of heat transfer to assist surgeons with cryosurgery, a
technique in which the ultralow temperature of liquid nitrogen is used to
destroy malignant tumors. Tissue engineering and the development of artificial
organs are other fi elds where mechanical engineers contribute, and they often
work with physicians and scientists to restore damaged skin, bone, and
cartilage in the human body.
Codes and
standards.
The products
that engineers design must connect to, and be compatible with, the hardware
that is developed by others. Because of codes and standards, you can have
confidence that a stereo will plug into an electrical outlet in California just
as well as it does in Florida and that the outlet’s voltage will be the same;
that the gasoline purchased next month will work in your car just as well as
the fuel purchased today; and that the socket wrench purchased at an automobile
parts store in the United States will fit the bolts on a vehicle that was
manufactured in Germany. Codes and standards are necessary to specify the
physical characteristics of mechanical parts so that others can clearly
understand their structure and operation. Many standards are developed through
consensus among governments and industry groups, and they have become
increasingly important as companies compete internationally for business. Codes
and standards involve a collaboration among trade associations, professional
engineering societies such as the American Society of Mechanical Engineers,
testing groups such as Underwriters Laboratories, and organizations such as the
American Society of Testing and Materials. The safety of bicycle and motorcycle
helmets, the crash protection features of automobiles and child safety seats,
and the fi re resistance of home insulation are just some applications for
which these guidelines help engineers to design safe products.
CAREER PATHS
Now that we
have introduced the fi eld of mechanical engineering and some of the
profession’s most significant contributions, we next turn to the career options
where future mechanical engineers will face the global, social, and
environmental challenges around the world. Because such a wide variety of
industries employ mechanical engineers, the profession does not have a
one-size-fits-all job description. Mechanical engineers can work as designers,
researchers, and technology managers for companies that range in size from
small start-ups to large multinational corporations. To give you a glimpse of
the range of available opportunities, mechanical engineers can:
• Design and
analyze any component, material, module, or system for the next generation of
automobiles
• Design and analyze medical devices,
including aids for the disabled, surgical and diagnostic equipment,
prosthetics, and artificial organs
• Design and analyze efficient refrigeration,
heating, and air-conditioning systems
• Design and analyze the power and heat
dissipation systems for any number of mobile computing and networking devices
• Design and analyze advanced urban
transportation and vehicle safety systems
• Design and analyze sustainable forms of
energy that are more readily accessible by nations, states, cities, villages,
and people groups
• Design and analyze the next generation of
space exploration systems
• Design and analyze revolutionary
manufacturing equipment and automated assembly lines for a wide range of
consumer products
• Manage a diverse team of engineers in the
development of a global product platform, identifying customer, market, and
product opportunities
• Provide consultant services to any number of
industries, including chemical, plastics, and rubber manufacturing; petroleum
and coal production; computer and electronic products; food and beverage
production; printing and publishing; utilities; and service providers
• Work in public service for such governmental
agencies as the National Aeronautics and Space Administration, Department of
Defense, National Institute of Standards and Technology, Environmental
Protection Agency, and national research laboratories.
Historically,
mechanical engineers could take either a technical track or a management track
with their careers. However, the lines between these tracks are blurring as
emerging product development processes are demanding knowledge not only about
technical issues but also about economic, environmental, customer, and
manufacturing issues. Job openings historically labeled as “mechanical
engineer” now include a number of diverse titles that reflect the changing
nature of the profession. For example, the following job position titles all
required a degree in mechanical engineering (taken from a leading job Web
site):
• Product
engineer
• Design
engineer
• Systems
engineer
• Power
engineer
•
Manufacturing engineer
• Packaging
engineer
• Renewable
energy consultant
•
Electro-mechanical engineer
•
Applications engineer
• Facilities
design engineer
• Product
applications engineer
• Mechanical
product engineer
• Mechanical
device engineer
• Energy
efficiency engineer
• Process
development engineer
•
Mechatronics engineer
• Principal
engineer
• Project
capture engineer
• Sales engineer
• Plant engineer
TYPICAL PROGRAM OF STUDY
As you begin
to study mechanical engineering, your program will most likely include the following
four components:
• General
education courses in the humanities, social sciences, and fi ne arts
• Preparatory courses in mathematics, science,
and computer programming
• Core courses in fundamental mechanical
engineering subjects
• Elective courses on specialized topics that
you find particularly interesting
After
completing the core curriculum, you often will have the flexibility to build an
individualized program of study through elective courses in such fields as
aerospace engineering, automotive engineering, computer-aided design,
manufacturing, biomedical engineering, and robotics, among other fields. The
major topics in a typical mechanical engineering curriculum are shown in
Figure. While the topics are allocated into separate branches, the mechanical
engineering curriculum is becoming an integrated system with interrelationships
among many of the courses, topics, and knowledge areas. At the heart of being a
mechanical engineer are innovation and design. An important place to start your
study is to understand that the design of products, systems, and processes is
how mechanical engineers impact the social, global, environmental, and economic
challenges in the world.
SUMMARY
This chapter
is intended to give you a perspective on the purpose, challenges,
responsibilities, rewards, and satisfaction of being a mechanical engineer.
Simply stated, engineers conceive, design, and build things that work and
impact lives. Engineers are regarded as being good problem solvers who can
clearly communicate the results of their work to others through drawings,
written reports, and verbal presentations. Mechanical engineering is a diverse
discipline, and it is generally regarded as being the most flexible of the
traditional engineering fi elds. In Section 1.3, the top ten contributions of
the mechanical engineering profession were described as having improved the day
to-day lives of literally billions of people. To accomplish those achievements,
mechanical engineers use computer-aided software tools for designing,
simulating, and manufacturing. Technologies that you may have previously taken
for granted—such as abundant and inexpensive electricity, refrigeration, and
transportation take on new meanings as you reflect on their importance to our
society and on the remarkable hardware that makes them possible.
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