What is Mechanical Engineering?

My personal definition of Mechanical Engineering is
If it needs engineering but it doesn’t involve electrons, chemical reactions, arrangement of molecules, life forms, isn’t
a structure (building/bridge/dam) and doesn’t fly, a mechanical engineer will take care of it… but
if it does involve electrons, chemical reactions, arrangement of molecules, life forms, is a structure or does fly,
mechanical engineers may handle it anyway
Although every engineering faculty member in every engineering department will claim that
his/her field is the broadest engineering discipline, in the case of Mechanical Engineering that’s
actually true (I claim) because the core material permeates all engineering systems (fluid mechanics,
solid mechanics, heat transfer, control systems, etc.)
Mechanical engineering is one of the oldest engineering fields (though perhaps Civil Engineering
is even older) but in the past 20 years has undergone a rather remarkable transformation as a result
of a number of new technological developments including

• Computer Aided Design (CAD). The average non-technical person probably thinks that
mechanical engineers sit in front of a drafting table drawing blueprints for devices having nuts,
bolts, shafts, gears, bearings, levers, etc. While that image was somewhat true 100 years ago,
today the drafting board has long since been replaced by CAD software, which enables a part to
be constructed and tested virtually before any physical object is manufactured.
• Simulation. CAD allows not only sizing and checking for fit and interferences, but the
resulting virtual parts are tested structurally, thermally, electrically, aerodynamically, etc. and
modified as necessary before committing to manufacturing.
• Sensor and actuators. Nowadays even common consumer products such as automobiles have
dozens of sensors to measure temperatures, pressures, flow rates, linear and rotational speeds,
etc. These sensors are used not only to monitor the health and performance of the device, but
also as inputs to a microcontroller. The microcontroller in turn commands actuators that adjust
flow rates (e.g. of fuel into an engine), timings (e.g. of spark ignition), positions (e.g. of valves),
etc.

• 3D printing. Traditional “subtractive manufacturing” consisted of starting with a block or
casting of material and removing material by drilling, milling, grinding, etc. The shapes that can
be created in this way are limited compared to modern “additive manufacturing” or “3D
printing” in which a structure is built in layers. Just as CAD + simulation has led to a new way
of designing systems, 3D printing has led to a new way of creating prototypes and in limited
cases, full-scale production.
• Collaboration with other fields. Historically, a nuts-and-bolts device such as an automobile
was designed almost exclusively by mechanical engineers. Modern vehicles have vast electrical
and electronic systems, safety systems (e.g. air bags, seat restraints), specialized batteries (in thecase of hybrids or electric vehicles), etc.,

which require design contributions from electrical,
biomechanical and chemical engineers, respectively. It is essential that a modern mechanical
engineer be able to understand and accommodate the requirements imposed on the system by
non-mechanical considerations.
These radical changes in what mechanical engineers do compared to a relatively short time ago
makes the field both challenging and exciting.
Mechanical Engineering curriculum
In almost any accredited Mechanical Engineering program, the following courses are required:
• Basic sciences - math, chemistry, physics
• Breadth or distribution (called “General Education” at USC)
• Computer graphics and computer aided design (CAD)
• Experimental engineering & instrumentation
• Mechanical design - nuts, bolts, gears, welds
• Computational methods - converting continuous mathematical equations into discrete
equations solved by a computer
• Core “engineering science”
o Dynamics – essentially F = ma applied to many types of systems
o Strength and properties of materials
o Fluid mechanics
o Thermodynamics
o Heat transfer
o Control systems
• Senior “capstone” design project
Additionally you may participate in non-credit “enrichment” activities such as undergraduate
research, undergraduate student paper competitions in ASME (American Society of Mechanical
Engineers, the primary professional society for mechanical engineers), the SAE Formula racecar
project, etc.
Examples of industries employing MEs
Many industries employ mechanical engineers; a few industries and the type of systems MEs
design are listed below.
o Automotive
• Combustion
• Engines, transmissions
• Suspensions
o Aerospace (w/ aerospace engineers)
• Control systems
• Heat transfer in turbines
• Fluid mechanics (internal & external)
o Biomedical (w/ physicians)
• Biomechanics – prosthesis
• Flow and transport in vivo
o Computers (w/ computer engineers)
• Heat transfer
• Packaging of components & systems
o Construction (w/ civil engineers)
• Heating, ventilation, air conditioning (HVAC)
• Stress analysis
o Electrical power generation (w/ electrical engineers)
• Steam power cycles - heat and work
• Mechanical design of turbines, generators, ...
o Petrochemicals (w/ chemical, petroleum engineers)
• Oil drilling - stress, fluid flow, structures
• Design of refineries - piping, pressure vessels
o Robotics (w/ electrical engineers)
• Mechanical design of actuators, sensors
• Stress analysis.