1. The main branches of engineering - what they deal with.
Historically the main Branches of Engineering are categorized as follows:
" Aerospace Engineering - The design of aircraft, spacecraft and related topics.
" Chemical Engineering - The conversion of raw materials into usable commodities
and the optimization of flow systems, especially separations.
" Civil Engineering - The design and construction of public and private works, such
as infrastructure (roads, railways, water supply and treatment etc.), bridges and
buildings.
" Electrical Engineering - The design of electrical systems, such as transformers, as
well as electronic goods.
" Mechanical Engineering - The design of physical or mechanical systems, such as
engines, powertrains, kinematic chains and vibration isolation equipment.
With the rapid advancement of Technology many new fields are gaining prominence and
new branches are developing such as Computer Engineering, Software Engineering,
Nanotechnology, Molecular engineering, Mechatronics etc. These new specialties
sometimes combine with the traditional fields and form new branches such as
Mechanical Engineering and Mechatronics and Electrical and Computer Engineering.
2. What is mechatronics - the history of mechatronics.
Mechatronics (or Mechanical and Electronics Engineering) is the combination of
mechanical engineering, electronic engineering and computer engineering. The purpose
of this interdisciplinary engineering field is the study of automata from an engineering
perspective and serves the purposes of controlling advanced hybrid systems.
Mechatronics is centred on mechanics, electronics, control engineering, computing,
molecular engineering. Mechatronics was first coined by Mr. Tetsuro Mori, a senior
engineer of the Japanese company Yaskawa, in 1969. Mechatronics may alternatively be
referred to as "electromechanical systems" or less often as "control and automation
engineering".
3. What is computational mechanics ? What branches of science are important
for it and what do they deal with ?
Computational mechanics is the discipline concerned with the use of computational
methods to study phenomena governed by the principles of mechanics. Before the
emergence of computational science was widely considered to be a sub-discipline of
applied mechanics.
Computational mechanics is interdisciplinary. Its three pillars are mathematics,
computer science, and mechanics. The areas of mathematics most related to
computational mechanics are partial differential equations, linear algebra and numerical
analysis. Some examples where computational mechanics have been put to practical use
are vehicle crash simulation, petroleum reservoir modeling, biomechanics, glass
manufacturing, and semiconductor modeling.
4. A definition of the gear - classification, application ?
A gear is a component within a transmission device that transmits rotational force to
another gear or device. Depending on their construction and arrangement, geared
devices can transmit forces at different speeds, torques, or in a different direction, from
the power source.
Gear Types Based upon the Shaft Arrangement, the Number of Steps, Housing Design,
the Peripheral Velocity, Manufacturing Precision, Pitch Diameter.
Application to transmissions provide a speed-torque conversion from a higher speed
motor to a slower but more forceful output or vice-versa and to differential in car.
5. What is a pulley?
A pulley is a mechanism composed of a wheel with a groove between two flanges
around the wheel's circumference. Pulleys are used to change the direction of an applied
force, transmit rotational motion, or realize a mechanical advantage in either a linear or
rotational system of motion.
6. What is a lever - classification, examples of each kind.
In physics, a lever is a rigid object that is used with an appropriate fulcrum or pivot
point to multiply the mechanical force that can be applied to another object.
There are three classes of levers which represent variations in the location of the
fulcrum and the input and output forces.
A first-class lever is a lever in which the fulcrum is located between the input effort and
the output load for examples: seesaw, crowbar.
In a second class lever the input effort is located at the end of the bar and the fulcrum is
located at the other end of the bar, opposite to the input, with the output load at a point
between these two forces. Examples: paddle, wrench.
For this class of levers, the input effort is higher than the output load, which is different
from second-class levers and some first-class levers. Examples: broom, fishing rod.
7. Definition of a mechanical advantage - in what mechanisms is it used ?
In physics and engineering, mechanical advantage (MA) is the factor by which a
mechanism multiplies the force or torque put into it. Generally, the mechanical
advantage is calculated as follows: MA = output force / input force
The following simple machines exhibit a mechanical advantage:
* The beam shown is in static equilibrium around the fulcrum.
* Wheel and axle notion: A wheel is essentially a lever with one arm the distance
between the axle and the outer point of the wheel, and the other the radius of the axle.
* Pulley: Pulleys change the direction of a tension force on a flexible material, e.g. a rope
or cable.
* Screw: A screw is essentially an inclined plane wrapped around a cylinder.
8. What is a first class lever- how it works, examples.
A first-class lever is a lever in which the fulcrum is located between the input effort and
the output load. In operation, a force is applied to a section of the bar, which causes the
lever to swing about the fulcrum, overcoming the resistance force on the opposite side.
The fulcrum may be at the center point of the lever as in a seesaw or at any point
between the input and output. This supports the effort arm and the load. Examples:
seesaw, crowbar, scissors.
9. What is a second class lever- how it works, examples.
In a second class lever the input effort is located at the end of the bar and the fulcrum is
located at the other end of the bar, opposite to the input, with the output load at a point
between these two forces. Examples: paddle, wrench.
10. What is a third class lever- how it works, examples.
For this class of levers, the input effort is higher than the output load, which is different
from second-class levers and some first-class levers. However, the distance moved by
the resistance (load) is greater than the distance moved by the effort. Since this motion
occurs in the same length of time, the resistance necessarily moves faster than the effort.
Thus, a third-class lever still has its uses in making certain tasks easier to do. In third
class levers, effort is applied between the output load on one end and the fulcrum on the
opposite end. Examples: broom, fishing rod.
11. What are benefits of ISO standards.
For consumers, conformity of products and services to International Standards provides
assurance about their quality, safety and reliability.
For everyone, International Standards contribute to the quality of life in general by
ensuring that the transport, machinery and tools we use are safe.
For the planet we inhabit, International Standards on air, water and soil quality, on
emissions of gases and radiation and environmental aspects of products can contribute
to efforts to preserve the environment.
12. What is ISO- history, structure, aims.
ISO (International Organization for Standardization) is the world's largest developer and
publisher of International Standards.
International standardization began in the electrotechnical field: the International
Electrotechnical Commission (IEC) was established in 1906. Pioneering work in other
fields was carried out by the International Federation of the National Standardizing
Associations (ISA). In 1946, delegates from 25 countries met in London and decided to
create a new international (ISO) organization, of which the object would be "to facilitate
the international coordination and unification of industrial standards.
Increased emphasis on the role of top management; attention to resource availability;
Measurements extended to system, processes, and product
13. Characterize and describe 4 types of motion.
Rotational, Translational, Oscillatory (Vibratory) and Deformation
Rotational = planets orbits; Rotational motion occurs when an object spins. The earth is
in a constant state of motion. Every twenty-four hours it makes one complete rotation
about its axis
Translational = projectile path or linear; translational motion results in a change of
location. This category may seem ridiculous at first as motion implies a change in
location, but an object can be moving and yet not go anywhere. I get up in the morning
and go to work, but by evening I'm back at home
Oscillatory (Vibratory) = periodic like a pendulum, vibrations as in the vibrations of a
string or the oscillating movement of a photon which moves in a linear fashion while
vibrating (that sets the frequency); Oscillatory motion is repetitive and fluctuates
between two locations. In the previous example of going from home to work to home to
work I am moving, but in the end I haven't gone anywhere.
Deformation = motion inside of an object like tension, buckling, twisting, compression,
or expansion.
14. What is a cam- its structure, classification, devices which use them.
A cam is a projecting part of a rotating wheel or shaft that strikes a lever at one or more
points on its circular path. The cam can be a simple tooth, as is used to deliver pulses of
power to a steam hammer, for example, or an eccentric disc or other shape that
produces a smooth reciprocating motion in the follower which is a lever making contact
with the cam.
The cam can be seen as a device that translates movement from circular to
reciprocating. A common example is the camshaft of an automobile, which takes the
rotary motion of the engine and translates it into the reciprocating motion necessary to
operate the intake and exhaust valves of the cylinders.
The opposite operation, translation of reciprocating motion to circular motion, is done
by a crank. An example is the crankshaft of a car, which takes the reciprocating motion
of the pistons and translates it into the rotary motion necessary to operate the wheels.
Cams can also be viewed as information-storing and -transmitting devices
15. What is a mechanical linkage - types and motion.
A mechanical linkage is a series of rigid links connected with joints to form a closed
chain, or a series of closed chains. Each link has two or more joints, and the joints have
various degrees of freedom to allow motion between the links. A linkage is called a
mechanism if two or more links are movable with respect to a fixed link. Mechanical
linkages are usually designed to take an input and produce a different output, altering
the motion, velocity, acceleration, and applying mechanical advantage.
Four bar linkages are the simplest closed loop kinematic linkage. They perform a wide
variety of motions with a few simple parts. They were also popular in the past due to the
ease of calculations, prior to computers, compared to more complicated mechanisms.
16. What is a gear- its parts, how it works, its use.
A gear's most important feature is that gears of unequal sizes can be combined to
produce a mechanical advantage, so that the rotational speed and torque of the second
gear are different from that of the first. In the context of a particular machine, the term
"gear" also refers to one particular arrangement of gears among other arrangements.
The speed ratio is simply the reciprocal ratio of the numbers of teeth on the two gears.
(Speed A * Number of teeth A) = (Speed B * Number of teeth B)
This ratio is known as the gear ratio.
Gear types: External vs. internal gears, Spur gears, Helical gears, Double helical gears,
Bevel gears.
17. What is a reverse motion linkage - its parts, how it works.
REVERSE MOTION LINKAGE: As the top rod moves to the left the bottom rod moves to
the right. The bars move in opposite directions. Another way of describing this linkage is
the the direction of movement in one rod is reversed in the other rod. The fixed pivot is
the centre of rotation.
PARALLEL MOTION LINKAGE: As the large rod at the top of the diagram moves to the
left the two small rods at the bottom move to the right. All the rods are parallel to each
other.
CRANK AND SLIDER LINKAGE: The rods move forwards and backwards in slider. The
fixed pivot anchor the linkages to one place.
BELL CRANK LINKAGE: This linkage allows horizontal movement to be converted to
vertical movement. It also works the opposite way round. A practical example of this is
the brake mechanism on a bicycle.
18. What do we use pulley systems for?
Pulley systems are used in the real world to lift large masses onto tall heights. You might
have seen the workers repairing the roof of a house and using the pulley system to lift
their tools or materials to the roof.
The pulley system consists of one or more pulleys and a rope or a cable. The number of
pulleys used may increase or decrease the mechanical advantage of the system.
Generally, the higher the mechanical advantage is, the easier it is to lift the object that is
being lifted.
19. Definition and classification of plastics, their properties and applications.
Plastic is the general common term for a wide range of synthetic or semisynthetic
organic solid materials suitable for the manufacture of industrial products. Plastics are
typically polymers of high molecular weight, and may contain other substances to
improve performance and/or reduce costs. The common word "plastic" should not be
confused with the technical adjective "plastic", which is applied to any material which
undergoes a permanent change of shape. Type of plastic thermoplastics and
thermosetting plastics.
20. Explain the difference between thermoplastics and thermosetting plastics.
A thermoplastic is a plastic that melts to a liquid when heated and freezes to a brittle,
very glassy state when cooled sufficiently. Most thermoplastics are high-molecular-
weight polymers.
Thermosetting plastics are polymer materials that irreversibly cure form. The cure may
be done through heat, through a chemical reaction, or irradiation such as electron beam
processing.
The difference between thermoplastics and thermosetting plastics is that thermoplastics
become soft, remoldable and weldable when heat is added. Thermosetting plastics
however, when heated, will chemically decompose, so they can not be welded or
remolded. On the other hand, once a thermosetting is cured it tends to be stronger than
a thermoplastic.
21. Conductors and insulators - characterize and give examples.
Conductor is a material which contains movable electric charges. In metallic conductors,
such as copper or aluminium, the movable charged particles are electrons. Positive
charges may also be mobile in the form of atoms in a lattice missing electrons or ions,
such as in the electrolyte of a battery. In power engineering, an electrical wire is a length
of metal, usually surrounded by an insulating sheath, that is used to conduct electricity.
An insulator, also called a dielectric, is a material that resists the flow of electric current.
An insulating material has atoms with tightly bonded valence electrons. These materials
are used in parts of electrical equipment, also called insulators or insulation, intended to
support or separate electrical conductors without passing current through themselves.
The term is also used more specifically to refer to insulating supports that attach electric
power transmission wires to utility poles or pylons.
Some materials such as glass or Teflon are very good electrical insulators. A much larger
class of materials, for example rubber-like polymers and most plastics are still "good
enough" to insulate electrical wiring and cables even though they may have lower bulk
resistivity. These materials can serve as practical and safe insulators for low to moderate
voltages.
22. What are semi-conducting materials, examples.
A semiconductor is a solid material that has electrical conductivity between those of a
conductor and an insulator; it can vary over that wide range either permanently or
dynamically.
Semiconductors are essential in electronic technology. Semiconductor devices,
electronic components made of semiconductor materials, are essential in modern
consumer electronics, including computers, mobile phones, and digital audio players.
Silicon is used to create most semiconductors commercially. Dozens of other other
materials are used.
23. What are discrete electronic components - give examples, describe them.
An electronic component is a basic electronic element usually packaged in a discrete
form with two or more connecting leads or metallic pads. Components are intended to
be connected together, usually by soldering to a printed circuit board, to create an
electronic circuit with a particular function. Components may be packaged singly or in
more or less complex groups as integrated circuits.
A resistor is a two-terminal electronic component designed to oppose an electric current
by producing a voltage drop between its terminals in proportion to the current, that is,
in accordance with Ohm's law: V = IR.
A capacitor or condenser is a passive electronic component consisting of a pair of
conductors separated by a dielectric. Capacitors were discovered in 1745 and have
become ubiquitous within electronic and electrical systems.
Diode is a two-terminal device (thermionic diodes may also have one or two ancillary
terminals for a heater). Diodes have two active electrodes between which the signal of
interest may flow, and most are used for their unidirectional electric current property.
The varicap diode is used as an electrically adjustable capacitor.
A logic gate performs a logical operation on one or more logic inputs and produces a
single logic output. The logic normally performed is Boolean logic and is most commonly
found in digital circuits. Logic gates are primarily implemented electronically using
diodes or transistors, but can also be constructed using electromagnetic relays, fluidics,
optics, molecules, or even mechanical elements.
24. Advantages of CAD
Ç Precise
Ç 3D detailed drawing
Ç Computerised model to scale
Ç Test without having to produce it
Ç Drawings are device independent
Ç You can resize easily by using calculation
Ç More economical and efficient
Ç Smaller files than bitmapped images
Ç Easier to see the characteristics
Ç You can see the image in animation so you can get the feeling of it without having to
build it
25. What are traditional methods of engineering design? Describe their
disadvantages.
In traditional method of engineering design you must use paper, pencil. This method
isn t very precise and you must all part draw apart. You must lost a lot of time and
money to finish some project. If you want see animation you must imagine it. All
mistakes cause drawing project another time. Transport this imagine is comfortless too.