List of definitions of terms and concepts commonly used in mechanical engineering
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This glossary of mechanical engineering terms pertains specifically to
mechanical engineering and its sub-disciplines. For a broad overview of engineering, see
glossary of engineering.
Abrasion – is the process of scuffing, scratching, wearing down, marring, or rubbing away. It can be intentionally imposed in a controlled process using an abrasive. Abrasion can be an undesirable effect of exposure to normal use or exposure to the elements.
Absolute zero – is the lowest possible
temperature of a system, defined as zero
kelvin or −273.15 °C. No experiment has yet measured a temperature of absolute zero.
Accelerated life testing – is the process of testing a product by subjecting it to conditions (
stress,
strain, temperatures, voltage, vibration rate, pressure etc.) in excess of its normal service parameters in an effort to uncover faults and potential modes of failure in a short amount of time.[1][2] By analyzing the product's response to such tests,
engineers can make predictions about the service life and maintenance intervals of a product.[3][4]
Accuracy and precision – In measurement of a set, accuracy is closeness of the measurements to a specific value, while precision is the closeness of the measurements to each other. More commonly, accuracy or trueness is a description of systematic errors, a measure of
statistical bias, while precision is a description of random errors, a measure of
statistical variability; the two concepts are independent of each other. Alternatively,
ISO defines[10] accuracy as describing a combination of both random and systematic
observational error, so high accuracy requires both high precision and high trueness.
Ackermann steering geometry – is a geometric arrangement of linkages in the
steering of a
car or other
vehicle designed to solve the problem of wheels on the inside and outside of a turn needing to trace out
circles of different
radii. It was invented by the German carriage builder
Georg Lankensperger in Munich in 1817, then patented by his agent in England,
Rudolph Ackermann (1764–1834) in 1818 for horse-drawn carriages.
Erasmus Darwin may have a prior claim as the inventor dating from 1758.[11]
Acoustic droplet ejection– (ADE) uses a pulse of ultrasound to move low volumes of fluids (typically nanoliters or picoliters) without any physical contact. This technology focuses acoustic energy into a fluid sample in order to eject droplets as small as a
picoliter. ADE technology is a very gentle process. This feature makes the technology suitable for a wide variety of applications including
proteomics and cell-based assays.
Active cooling – An active cooling system is one that involves the use of energy to cool something, as opposed to
passive cooling that uses no energy. Such systems circulate a
coolant to
transfer heat from one place to another. The coolant is either a gas, such as in
air cooling of
computers, or a liquid such as in a
car engine. In the latter case, liquid is pumped to transfer heat from the engine to the radiator, which in turn is cooled by passing air over it. Other active cooling systems make use of a
refrigeration cycle.
Actual mechanical advantage – The actual mechanical advantage (AMA) is the mechanical advantage determined by physical measurement of the input and output forces. Actual mechanical advantage takes into account energy loss due to deflection, friction, and wear.
Adjoint equation – is a
linear differential equation, usually derived from its primal equation using
integration by parts. Gradient values with respect to a particular quantity of interest can be efficiently calculated by solving the adjoint equation. Methods based on solution of adjoint equations are used in
wing shape optimization, fluid flow control and
uncertainty quantification. For example this is an
Itō stochastic differential equation. Now by using Euler scheme, we integrate the parts of this equation and get another equation, , here is a random variable, later one is an adjoint equation.
Aerodynamics – is the study of the motion of
air, particularly its interaction with a solid object, such as an
airplane wing. It is a sub-field of
fluid dynamics and
gas dynamics, and many aspects of aerodynamics theory are common to these fields.
Agitator (device) – is a
device or
mechanism to put something into
motion by
shaking or
stirring. Agitators usually consist of an
impeller and a shaft; an impeller is a rotor located within a tube or conduit attached to the shaft, which helps enhance the pressure in order for the flow of a fluid be done.[12]
Air handler – An air handler, or air handling unit (often abbreviated to AHU), is a device used to regulate and circulate air as part of a heating, ventilating, and air-conditioning (
HVAC) system.[13]
Air compressor – is a device that
converts power (using an electric motor, diesel or gasoline engine, etc.) into
potential energy stored in pressurized air (i.e.,
compressed air). By one of several methods, an air compressor forces more and more air into a storage tank, increasing the pressure. When tank pressure reaches its engineered upper limit the air compressor shuts off. The compressed air, then, is held in the tank until called into use.[14]
Air conditioner – Air conditioning (often referred to as AC, A/C, or air con)[15] is the process of removing heat and moisture from the interior of an occupied space, to improve the comfort of occupants. Air conditioning can be used in both domestic and commercial environments.
Air preheater – (APH) is any device designed to heat
air before another process (for example,
combustion in a
boiler) with the primary objective of increasing the thermal efficiency of the process. They may be used alone or to replace a
recuperative heat system or to replace a steam coil.
Airflow – Airflow, or air flow is the movement of air from one area to another. The primary cause of airflow is the existence of
pressure gradients. Air behaves in a
fluid manner, meaning particles naturally flow from areas of higher pressure to those where the pressure is lower.
Atmospheric air pressure is directly related to altitude, temperature, and composition.[16][17] In
engineering, airflow is a measurement of the amount of
air per unit of time that flows through a particular device.
Allowance – is a planned deviation between an exact dimension and a
nominal or
theoretical dimension, or between an intermediate-stage dimension and an intended final dimension. The unifying abstract concept is that a certain amount of difference allows for some known factor of compensation or interference. For example, an area of excess metal may be left because it is needed to complete subsequent machining. Common cases are listed below. An allowance, which is a planned deviation from an ideal, is contrasted with a tolerance, which accounts for expected but unplanned deviations.
Applied mechanics – describes the behavior of a body, in either a beginning state of rest or of motion, subjected to the action of forces.[21] Applied mechanics, bridges the gap between physical theory and its application to
technology. It is used in many fields of
engineering, especially
mechanical engineering and
civil engineering. In this context, it is commonly referred to as Engineering Mechanics.
Artificial intelligence – (AI), sometimes called machine intelligence, is
intelligence demonstrated by
machines, in contrast to the natural intelligence displayed by humans and other animals. In
computer science AI research is defined as the study of "
intelligent agents": any device that perceives its environment and takes actions that maximize its chance of successfully achieving its goals.[23] Colloquially, the term "artificial intelligence" is applied when a machine mimics "cognitive" functions that humans associate with other
human minds, such as "learning" and "problem solving".[24]
Automobile – is a wheeled
motor vehicle used for
transportation. Most definitions of car say they run primarily on roads, seat one to eight people, have four
tires, and mainly transport people rather than goods.[26][27]
Automobile handling – Automobile handling and vehicle handling are descriptions of the way a wheeled vehicle responds and reacts to the inputs of a driver, as well as how it moves along a track or road. It is commonly judged by how a vehicle performs particularly during
cornering, acceleration, and braking as well as on the vehicle's
directional stability when moving in steady state condition.
Automotive engineering – Automotive engineering, along with
aerospace engineering and
marine engineering, is a branch of vehicle engineering, incorporating elements of
mechanical,
electrical,
electronic,
software and
safety engineering as applied to the design, manufacture and operation of
motorcycles,
automobiles and
trucks and their respective engineering subsystems. It also includes modification of vehicles. Manufacturing domain deals with the creation and assembling the whole parts of automobiles is also included in it. The automotive engineering field is research -intensive and involves direct application of mathematical models and formulas. The study of automotive engineering is to design, develop, fabricate, and testing vehicles or vehicle components from the concept stage to production stage. Production, development, and manufacturing are the three major functions in this field.
Axle – is a central shaft for a
rotating wheel or gear. On wheeled vehicles, the axle may be fixed to the wheels, rotating with them, or fixed to the vehicle, with the wheels rotating around the axle.[28] In the former case,
bearings or
bushings are provided at the mounting points where the axle is supported. In the latter case, a bearing or bushing sits inside a central hole in the wheel to allow the wheel or gear to rotate around the axle. Sometimes, especially on bicycles, the latter type axle is referred to as a spindle.
Backdrive – is a component used in reverse to obtain its input from its output. This extends to many concepts and systems from thought based to practical mechanical applications.
Backlash – sometimes called lash or play, is a clearance or lost motion in a mechanism caused by gaps between the parts. It can be defined as "the maximum distance or angle through which any part of a
mechanical system may be moved in one direction without applying appreciable force or motion to the next part in mechanical sequence",[30]p. 1-8.
Ball detent – is a simple mechanical arrangement used to hold a moving part in a temporarily fixed position relative to another part. Usually the moving parts slide with respect to each other, or one part rotates within the other.
Ball screw – is a mechanical
linear actuator that translates rotational motion to linear motion with little
friction. A threaded shaft provides a helical raceway for
ball bearings which act as a precision screw. As well as being able to apply or withstand high thrust loads, they can do so with minimum internal friction.
Ball spline – Ball splines (Ball Spline
bearings) are a special type of
linear motion bearing that are used to provide nearly frictionless linear motion while allowing the member to transmit torque simultaneously. There are
grooves ground along the length of the shaft (thus forming
splines) for the recirculating ground balls to run inside. The outer shell that houses the balls is called a nut rather than a
bushing, but is not a nut in the traditional sense—it is not free to rotate about the shaft, but is free to travel up and down the shaft.
Beale Number – is a parameter that characterizes the performance of
Stirling engines. It is often used to estimate the power output of a Stirling engine design. For engines operating with a high temperature differential, typical values for the Beale number range from ( 0.11 ) to ( 0.15 ); where a larger number indicates higher performance.
Bearing pressure – is a particular case of
contact mechanics often occurring in cases where a convex surface (male cylinder or sphere) contacts a concave surface (female cylinder or sphere:
bore or
hemispherical cup). Excessive contact pressure can lead to a typical bearing failure such as a plastic deformation similar to
peening. This problem is also referred to as bearing resistance.[31]
Bearing surface – is the
area of contact between two objects. It usually is used in reference to
bolted joints and
bearings, but can be applied to a wide variety of engineering applications. On a
screw the bearing area loosely refers to the underside of the head.[32] Strictly speaking, the bearing area refers to the area of the screw head that directly bears on the part being fastened.[33] For a cylindrical bearing it is the
projected area perpendicular to the applied force.[34] On a
spring the bearing area refers to the amount of area on the top or bottom surface of the spring in contact with the constraining part.[35] The ways of
machine tools, such as dovetail slides, box ways, prismatic ways, and other types of machine slides are also bearing surfaces.
Belt – is a loop of flexible material used to link two or more rotating
shafts mechanically, most often parallel. Belts may be used as a source of motion, to
transmit power efficiently or to track relative movement. Belts are looped over
pulleys and may have a twist between the pulleys, and the shafts need not be parallel.
Belt friction – is a term describing the friction forces between a
belt and a surface, such as a belt wrapped around a
bollard. When one end of the belt is being pulled only part of this force is transmitted to the other end wrapped about a surface. The friction force increases with the amount of wrap about a surface and makes it so the
tension in the belt can be different at both ends of the belt. Belt friction can be modeled by the
Belt friction equation.[36]
Bending – In
applied mechanics, bending (also known as flexure) characterizes the behavior of a slender
structural element subjected to an external
load applied perpendicularly to a longitudinal axis of the element.
Body in white - or BIW refers to the stage in
automobile manufacturing in which a car body's components have been joined together, using one or a combination of different techniques: welding (spot, MIG/MAG), riveting, clinching, bonding, laser brazing etc. BIW is termed before painting & before the engine, chassis sub-assemblies, or trim (glass, door locks/handles, seats, upholstery, electronics, etc.) have been assembled in the frame structure.
Bogie – is a
chassis or framework that carries a
wheelset, attached to a vehicle—a
modular subassembly of
wheels and
axles. Bogies take various forms in various modes of transport.
Bonded seal – is a type of
washer used to provide a
seal around a screw or bolt. Originally made by
Dowty Group, they are also known as Dowty seals or Dowty washers.[38] Now widely manufactured, they are available in a range of standard sizes and materials [39][40][41]
Brittleness – A material is brittle if, when subjected to
stress, it breaks without significant
plastic deformation. Brittle materials absorb relatively little
energy prior to fracture, even those of high
strength.
Buckling – is instability that leads to a
failure mode. When a structure is subjected to
compressivestress, buckling may occur. Buckling is characterized by a sudden sideways deflection of a structural member. This may occur even though the stresses that develop in the structure are well below those needed to cause failure of the material of which the structure is composed.
Bus- A bus (archaically also omnibus,[42]multibus, motorbus, autobus) is a
road vehicle designed to carry many
passengers.
Bushing – or rubber bushing is a type of
vibration isolator. It provides an interface between two parts, damping the energy transmitted through the bushing. A common application is in
vehicle suspension systems, where a bushing made of
rubber (or, more often,
synthetic rubber or
polyurethane) separates the faces of two metal objects while allowing a certain amount of movement. This movement allows the suspension parts to move freely, for example, when traveling over a large bump, while minimizing transmission of noise and small vibrations through to the chassis of the vehicle. A rubber bushing may also be described as a flexible mounting or antivibration mounting.
Car handling – Automobile handling and vehicle handling are descriptions of the way a wheeled vehicle responds and reacts to the inputs of a driver, as well as how it moves along a track or road. It is commonly judged by how a vehicle performs particularly during
cornering, acceleration, and braking as well as on the vehicle's
directional stability when moving in steady state condition.
Carbon fiber reinforced polymer – or carbon fiber reinforced plastic, or carbon fiber reinforced thermoplastic (CFRP, CRP, CFRTP, or often simply carbon fiber, carbon composite, or even carbon), is an extremely strong and light
fiber-reinforced plastic which contains
carbon fibers.
Carbon fibers – or carbon fibres (alternatively CF, graphite fiber or graphite fibre) are
fibers about 5–10
micrometres in diameter and composed mostly of
carbon atoms. Carbon fibers have several advantages including high stiffness, high tensile strength, low weight, high chemical resistance, high temperature tolerance and low thermal expansion. These properties have made carbon fiber very popular in aerospace, civil engineering, military, and motorsports, along with other competition sports. However, they are relatively expensive when compared with similar fibers, such as
glass fibers or plastic fibers.
Clean room design – is the method of copying a design by
reverse engineering and then recreating it without infringing any of the
copyrights associated with the original design. Clean-room design is useful as a defense against copyright infringement because it relies on independent invention. However, because independent invention is not a defense against
patents, clean-room designs typically cannot be used to circumvent patent restrictions.
Clevis fastener – Fastener consisting of a U-shaped bracket through which a pin is placed
Clock – is an instrument used to measure, keep, and indicate
time. The clock is one of the oldest human
inventions, meeting the need to measure intervals of time shorter than the natural units: the
day, the
lunar month, and the
year. Devices operating on several physical processes have been used over the millennia.
Clutch – is a mechanical device which engages and disengages power transmission especially from
driving shaft to driven shaft.
CNC – (CNC)), is the
automated control of
machining tools (drills, boring tools, lathes) by means of a
computer. An NC machine alters a blank piece of material (metal, plastic, wood, ceramic, or composite) to meet precise specifications by following programmed instructions and without a manual operator.
Coefficient of thermal expansion – describes how the size of an object changes with a change in temperature. Specifically, it measures the fractional change in size per degree change in temperature at a constant pressure. Several types of coefficients have been developed: volumetric, area, and linear. The choice of coefficient depends on the particular application and which dimensions are considered important.
Coil spring – also known as a helical spring, is a mechanical device which is typically used to store energy and subsequently release it, to absorb shock, or to maintain a force between contacting surfaces. They are made of an
elastic material formed into the shape of a
helix which returns to its natural length when unloaded.
Composite material – (also called a composition material, or shortened to composite), is a material made from two or more constituent materials with significantly different
physical or
chemical properties that, when combined, produce a material with characteristics different from the individual components. The individual components remain separate and distinct within the finished structure, differentiating composites from
mixtures and
solid solutions.
Compressive strength – or compression strength is the capacity of a material or structure to withstand loads tending to reduce size, as opposed to
tensile strength, which withstands loads tending to elongate. In other words, compressive strength resists
compression (being pushed together), whereas tensile strength resists
tension (being pulled apart). In the study of
strength of materials, tensile strength, compressive strength, and
shear strength can be analyzed independently.
Computer – is a device that can be instructed to carry out
sequences of
arithmetic or
logical operations automatically via
computer programming. Modern computers have the ability to follow generalized sets of operations, called programs. These programs enable computers to perform an extremely wide range of tasks. A "complete" computer including the
hardware, the
operating system (main
software), and
peripheral equipment required and used for "full" operation can be referred to as a computer system. This term may as well be used for a group of computers that are connected and work together, in particular a
computer network or
computer cluster.
Computer-aided design – (CAD) is the use of
computer systems (or workstations) to aid in the creation, modification, analysis, or optimization of a
design.[46] CAD software is used to increase the productivity of the designer, improve the quality of design, improve communications through documentation, and to create a database for manufacturing.[47] CAD output is often in the form of electronic files for print, machining, or other manufacturing operations. The term CADD (for Computer Aided Design and Drafting) is also used.[48]
Computer-aided manufacturing - (CAM) is the use of software to control
machine tools and related ones in the
manufacturing of workpieces.[49][50][51][52][53] This is not the only definition for CAM, but it is the most common;[49] CAM may also refer to the use of a computer to assist in all operations of a manufacturing plant, including planning, management, transportation and storage.[54][55]
Computer numerical control – Numerical control (NC), (also computer numerical control (CNC)), is the
automated control of
machining tools (drills, boring tools, lathes) and
3D printers by means of a
computer. An NC machine alters a blank piece of material (metal, plastic, wood, ceramic, or composite) to meet precise specifications by following programmed instructions and without a manual operator.
Conservation of mass – The law of conservation of mass or principle of mass conservation states that for any
system closed to all transfers of
matter and
energy, the
mass of the system must remain constant over time, as system's mass cannot change, so quantity can neither be added nor be removed. Hence, the quantity of mass is conserved over time.
Continuum mechanics – is a branch of
mechanics that deals with the mechanical behavior of materials modeled as a continuous mass rather than as discrete particles.
Control theory – in
control systems engineering is a subfield of
mathematics that deals with the control of continuously operating
dynamical systems in engineered processes and machines. The objective is to develop a control model for controlling such systems using a control action in an optimum manner without delay or overshoot and ensuring control
stability.
Corrosion – is a
natural process that converts a refined metal to a more chemically-stable form, such as its
oxide,
hydroxide, or
sulfide. It is the gradual destruction of materials (usually
metals) by chemical and/or electrochemical reaction with their environment.
Corrosion engineering is the field dedicated to controlling and stopping corrosion.
Cotter pin – is a pin or wedge passing through a hole to fix parts tightly together.
Damping ratio – is an influence within or upon an
oscillatory system that has the effect of reducing, restricting or preventing its oscillations. In physical systems, damping is produced by processes that dissipate the energy stored in the oscillation.[56] Examples include
viscousdrag in mechanical systems,
resistance in
electronic oscillators, and absorption and scattering of light in
optical oscillators.
Deformation (engineering) – refers to the change in size or shape of an object. Deformation that is reversible is termed as
elastic deformation, while irreversible deformation is termed
plastic deformation. Strain is the relative deformation of an infinitesimally small cube of material, and is generally linearly proportional to the forces or
stresses acting on the cube while the deformation is elastic. The determination of the stress and strain throughout a solid object is given by the field of
strength of materials and for a structure by
structural analysis.
Design for manufacturability – (also sometimes known as design for manufacturing or DFM), is the general engineering practice of
designing products in such a way that they are easy to manufacture. The concept exists in almost all engineering disciplines, but the implementation differs widely depending on the manufacturing technology.
Differential –A differential is a gear train with three shafts that has the property that the rotational speed of one shaft is the average of the speeds of the others, or a fixed multiple of that average.
Diode – is a two-
terminalelectronic component that conducts
current primarily in one direction (asymmetric
conductance); it has low (ideally zero)
resistance in one direction, and high (ideally infinite)
resistance in the other. A diode
vacuum tube or thermionic diode is a vacuum tube with two
electrodes, a heated
cathode and a
plate, in which electrons can flow in only one direction, from cathode to plate. A semiconductor diode, the most commonly used type today, is a
crystalline piece of
semiconductor material with a
p–n junction connected to two electrical terminals.[58]
Driveshaft – a component for transmitting mechanical
power and
torque and rotation, usually used to connect other components of a
drivetrain that cannot be connected directly because of distance or the need to allow for relative movement between them.
Elasticity – In
physics, elasticity is the ability of a body to resist a distorting influence and to return to its original size and shape when that influence or force is removed. Solid objects will
deform when adequate
forces are applied to them. If the material is elastic, the object will return to its initial shape and size when these forces are removed. Hooke's law states that the force should be proportional to the extension. The physical reasons for elastic behavior can be quite different for different materials. In metals, the atomic lattice changes size and shape when forces are applied (energy is added to the system). When forces are removed, the lattice goes back to the original lower energy state. For
rubbers and other polymers, elasticity is caused by the stretching of polymer chains when forces are applied.
Electrical engineering – Electrical engineering is an engineering discipline concerned with the study, design and application of equipment, devices and systems which use electricity, electronics, and electromagnetism.
Electrical circuit – An electrical network consisting of a closed loop, giving a return path for the current.
Engineering drawing – a type of
technical drawing that is used to convey information about an object. Detail drawings commonly specify the
dimensions and
tolerances for the construction of a single component, while a master drawing or assembly drawing links the detail drawings for each component in a system. Only required information is typically specified, usually only in one place to avoid inconsistency.
Engineering economics – a subset of economics that studies the behavior of individuals and firms in making engineering decisions regarding the allocation of limited resources. It is a simplified application of
microeconomics in that it assumes elements such as price determination, competition and demand/supply to be fixed inputs.
Engineering management – the combination of technological problem-solving and the organizational, administrative, legal and planning abilities of
management in order to oversee the operational performance of complex engineering driven enterprises.
Engineering society – a
professional organization for
engineers of various
disciplines. Some are umbrella type organizations which accept many different disciplines, while others are discipline-specific. There are also many student-run engineering societies, commonly at universities or technical colleges.
Exploratory engineering – the process of designing and analyzing detailed hypothetical models of systems that are not feasible with current technologies or methods, but do seem to be clearly within the bounds of what science considers to be possible. It usually results in
prototypes or
computer simulations that are as convincing as possible to those that know the relevant science, given the lack of experimental confirmation.
Friction – the
force resisting the relative motion of solid surfaces, fluid layers, and material elements
sliding against each other. There are several types of friction including static friction between non-moving surfaces and kinetic friction between moving surfaces; for two given solid surfaces, static friction is greater than kinetic friction. Fluid friction describes the friction between layers of a
viscous fluid that are moving relative to each other.
Gear – a
rotating circular
machine part having cut or inserted teeth which mesh with another compatible toothed part to transmit
torque and speed. Each gear tooth essentially functions as a
lever with its
fulcrum at the gear's center.
Gear coupling – a mechanical device for transmitting
torque between two shafts that are not
collinear. It consists of a flexible joint fixed to each shaft. The two joints are connected by a third shaft, called the spindle.
Invention – a unique or novel device, method, composition, idea or process. An inventor who creates or discovers a new invention can sometimes receive a
patent, or legal right to exclude others from making, using, or selling that invention for a limited time.
Joule – the
SI unit of
energy, which uses the symbol J. It is equal to the amount of
work done when a force of 1
newton displaces a mass through a distance of 1
metre in the direction of the force applied. It is also the energy dissipated as heat when an
electric current of one
ampere passes through a
resistance of one
ohm for one second.
K
Kelvin – the primary
SI unit of
temperature, which uses the symbol K and has
absolute zero as its zero point. The temperature in
degree Celsius is defined as the temperature in kelvins minus 273.15 (i.e. 0 °C is equal to 273.15 K).
Lever – a
simple machine consisting of a
beam or rigid rod pivoted at a fixed
hinge, or fulcrum. A lever amplifies an input force to provide a greater output force, which is said to provide leverage. The ratio of the output force to the input force is the
mechanical advantage of the lever.
Machinery's Handbook – is a classic, one-volume reference work in mechanical engineering and practical
workshopmechanics published by
Industrial Press, New York, since 1914; its 31st edition was published in 2020. Recent editions of the handbook contain chapters on mathematics, mechanics, materials, measuring, toolmaking, manufacturing, threading, gears, and machine elements, combined with excerpts from
ANSI standards.
Ohm's law – states that the
current through a
conductor between two points is directly
proportional to the
voltage across the two points. It is typically expressed as the equation I = V ÷ R, where I is the current through the conductor, V is the voltage measured across the conductor and R is the
resistance of the conductor.
Professional Engineer (PE) – In the United States, this designation is given to engineers who have passed the
Principles and Practice of Engineering exam, or PE exam. Upon passing the PE exam and meeting other eligibility requirements, that vary by state, such as education and experience, an engineer can then become registered in their State to stamp and sign engineering drawings and calculations as a PE.
Second Law of Thermodynamics - states that when
energy changes from one form to another form, or matter moves freely,
entropy (disorder) in a closed system increases. In other words, heat always moves from hotter objects to colder objects unless energy is supplied to reverse the direction of
heat flow, and not all heat energy can be converted into
work in a
cyclic process.
Stress-strain curve – a chart which gives the relationship between
stress and
strain for a given material. It is obtained by gradually applying
load to a test coupon and measuring the
deformation.
Technology – refers to both the application of
knowledge for achieving practical
goals in a
reproducible way, and the products and
tools resulting from such efforts.
Tensile strength – also called ultimate tensile strength or ultimate strength, is the maximum
stress that a material can withstand while being stretched or pulled before breaking. In
brittle materials the ultimate tensile strength is close to the
yield point, whereas in
ductile materials the ultimate tensile strength can be higher.
Third Law of Thermodynamics - states that the
entropy of a system approaches a constant value when its temperature approaches
absolute zero, because its
atoms would stop moving. However,
heat transfer between the system and its surroundings would prevent the system from ever reaching absolute zero.
Valve – a device or natural object (such as a
heart valve) that regulates, directs or controls the flow of a fluid (gases, liquids, fluidized solids, or
slurries) by opening, closing, or partially obstructing various passageways
Vector – a geometric object that has
magnitude (or
length) and
direction. A vector quantity is differentiated from a scalar quantity which only has magnitude, not direction. Vectors can be added to other vectors according to
vector algebra[disambiguation needed].
Wear – is the damaging, gradual removal or deformation of material at
solid surfaces. Causes of wear can be mechanical (e.g.,
erosion) or
chemical (e.g.,
corrosion). The study of wear and related processes is referred to as
tribology.
Wedge – is a
triangular shaped tool, and is a portable
inclined plane, and one of the six classical
simple machines. It can be used to separate two objects or portions of an object, lift up an object, or hold an object in place. It functions by converting a
force applied to its blunt end into forces perpendicular (
normal) to its inclined surfaces. The
mechanical advantage of a wedge is given by the ratio of the length of its slope to its width.[61][62] Although a short wedge with a wide angle may do a job faster, it requires more force than a long wedge with a narrow angle.
Wheel – In its primitive form, a wheel is a circular block of a hard and durable material at whose center has been bored a hole through which is placed an
axlebearing about which the wheel rotates when
torque is applied to the wheel about its axis. The
wheel and axle assembly can be considered one of the
six simple machines.
Wheel and axle – is a machine consisting of a
wheel attached to a smaller
axle so that these two parts rotate together in which a force is transferred from one to the other. The wheel and axle can be viewed as a version of the lever, with a drive force applied tangentially to the perimeter of the wheel and a load force applied to the axle, respectively, that are balanced around the hinge which is the fulcrum.
Wheelset – is the
wheel–
axle assembly of a
railroad car. The frame assembly beneath each end of a car,
railcar or
locomotive that holds the wheelsets is called the
bogie (or truck in
North America). Most North American
freight cars have two bogies with two or three wheelsets, depending on the type of car; short
freight cars generally have no bogies but instead have two wheelsets.
Yield point – In
materials science and
engineering, the yield point is the point on a
stress-strain curve that indicates the limit of
elastic behavior and the beginning of
plastic behavior. Below the yield point, a material will
deform elastically and will return to its original shape when the applied
stress is removed. Once the yield point is passed, some fraction of the deformation will be permanent and non-reversible and is known as
plastic deformation.
Yield strength – or yield stress, is a
material property and is the stress corresponding to the yield point at which the material begins to deform plastically. The yield strength is often used to determine the maximum allowable
load in a mechanical component, since it represents the upper limit to forces that can be applied without producing permanent deformation. In some materials, such as
aluminium, there is a gradual onset of non-linear behavior, making the precise yield point difficult to determine. In such a case, the offset yield point (or proof stress) is taken as the stress at which 0.2% plastic deformation occurs. Yielding is a gradual
failure mode which is normally not
catastrophic, unlike
ultimate failure.
Young's modulus – Young's modulus , the Young modulus or the
modulus of elasticity in tension, is a mechanical property that measures the tensile
stiffness of a
solid material. It quantifies the relationship between tensile
stress (force per unit area) and axial
strain (proportional deformation) in the
linear elastic region of a material and is determined using the formula:[63]
Young's moduli are typically so large that they are expressed not in
pascals but in gigapascals (GPa).
Z
Zero Defects – (or ZD), was a management-led program to eliminate defects in industrial production that enjoyed brief popularity in American industry from 1964[64] to the early 1970s. Quality expert
Philip Crosby later incorporated it into his "Absolutes of Quality Management" and it enjoyed a renaissance in the American automobile industry—as a performance goal more than as a program—in the 1990s. Although applicable to any type of enterprise, it has been primarily adopted within
supply chains wherever large volumes of components are being purchased (common items such as nuts and bolts are good examples).
Zeroth Law of Thermodynamics – If body A is in thermal equilibrium (no heat transfers between them when in contact) with body C, and body B is in thermal equilibrium with body C, then A is in thermal equilibrium with B.
^Nelson, W. (1980). "Accelerated Life Testing - Step-Stress Models and Data Analyses". IEEE Transactions on Reliability. R-29 (2): 103.
doi:
10.1109/TR.1980.5220742.
S2CID35734439.
^Tinder, Richard F. (2007). Relativistic Flight Mechanics and Space Travel: A Primer for Students, Engineers and Scientists. Morgan & Claypool Publishers. p. 33.
ISBN978-1-59829-130-8.
Extract of page 33
^2008 ASHRAE handbook : heating, ventilating, and air-conditioning systems and equipment (Inch-Pound ed.). Atlanta, Ga.: ASHRAE American Society of Heating, Refrigerating and Air-Conditioning Engineers. 2008.
ISBN9781933742335.
Poole, Mackworth & Goebel 1998,
p. 1, which provides the version that is used in this article. Note that they use the term "computational intelligence" as a synonym for artificial intelligence.
^Frederick M. Steingress (2001). Low Pressure Boilers (4th ed.). American Technical Publishers.
ISBN0-8269-4417-5.
^Frederick M. Steingress, Harold J. Frost and Darryl R. Walker (2003). High Pressure Boilers (3rd ed.). American Technical Publishers.
ISBN0-8269-4300-4.
^Lutjen, D; Müller, M (1984). Kfz-Rechnen. B.G. Teubner Stuttgart. p. 12.
ISBN9783519067214.
^Steidel (1971). An Introduction to Mechanical Vibrations. John Wiley & Sons. p. 37. damped, which is the term used in the study of vibration to denote a dissipation of energy
^Cantwell, W.J.; Morton, J. (1991). "The impact resistance of composite materials — a review". Composites. 22 (5): 347–362.
doi:
10.1016/0010-4361(91)90549-V.
^Fundamentals of Classical Thermodynamics, 3rd ed. p. 159, (1985) by G. J. Van Wylen and R. E. Sonntag: "A heat engine may be defined as a device that operates in a thermodynamic cycle and does a certain amount of net positive work as a result of heat transfer from a high-
temperature body and to a low-temperature body. Often the term heat engine is used in a broader sense to include all devices that produce work, either through heat transfer or combustion, even though the device does not operate in a thermodynamic cycle. The internal-combustion engine and the gas turbine are examples of such devices, and calling these heat engines is an acceptable use of the term."
^Mechanical efficiency of heat engines, p. 1 (2007) by James R. Senf: "Heat engines are made to provide mechanical energy from thermal energy."
^McGraw-Hill Concise Encyclopedia of Science & Technology, Third Ed., Sybil P. Parker, ed., McGraw-Hill, Inc., 1992, p. 2041.
^Jastrzebski, D. (1959). Nature and Properties of Engineering Materials (Wiley International ed.). John Wiley & Sons, Inc.
^A Guide to Zero Defects: Quality and Reliability Assurance Handbook. Washington, D.C.:
Office of the Assistant Secretary of Defense (Manpower Installations and Logistics). 1965. p. 3.
OCLC7188673. 4155.12-H.
Archived from the original on May 29, 2014. Retrieved May 29, 2014. Early in 1964 the Assistant Secretary of Defense (Installations and Logistics) invited the attention of the Military Departments and the
Defense Supply Agency to the potential of Zero Defects. This gave the program substantial impetus. Since that time Zero Defects has been adopted by numerous industrial and Department of Defense activities.
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