[course] robotics - notes - ieeealexsb

8/13/2019 [Course] Robotics - Notes - IEEEAlexSB

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I)Pneumatic:

Pneumatics is a branch of technology, which deals with the study and application of use of pressurizedgas to effect mechanical motion.

II)Hydraulic:

Hydraulic machines are machinery and tools that use liquid fluid power to do simple work. Heavy

equipment is a common example.

In this type of machine, hydraulic fluid is transmitted throughout the machine to various hydraulic

motors and hydraulic cylinders and which becomes pressurized according to the resistance present.

The fluid is controlled directly or automatically by control valves and distributed through

hoses and tubes.

Note:

Sometimes using the pneumatic systems is a must such as in food production industries ,And this isbecause air is not toxic.
http://en.wikipedia.org/wiki/Pressurized_gashttp://en.wikipedia.org/wiki/Pressurized_gashttp://en.wikipedia.org/wiki/Liquidhttp://en.wikipedia.org/wiki/Fluid_powerhttp://en.wikipedia.org/wiki/Engineering_vehiclehttp://en.wikipedia.org/wiki/Engineering_vehiclehttp://en.wikipedia.org/wiki/Hydraulic_fluidhttp://en.wikipedia.org/wiki/Hydraulic_motorhttp://en.wikipedia.org/wiki/Hydraulic_motorhttp://en.wikipedia.org/wiki/Hydraulic_cylinderhttp://en.wikipedia.org/wiki/Control_valveshttp://en.wikipedia.org/wiki/Hydraulic_machinery#Hose.2C_tubes_and_pipeshttp://en.wikipedia.org/wiki/Hydraulic_machinery#Hose.2C_tubes_and_pipeshttp://en.wikipedia.org/wiki/Control_valveshttp://en.wikipedia.org/wiki/Hydraulic_cylinderhttp://en.wikipedia.org/wiki/Hydraulic_motorhttp://en.wikipedia.org/wiki/Hydraulic_motorhttp://en.wikipedia.org/wiki/Hydraulic_fluidhttp://en.wikipedia.org/wiki/Engineering_vehiclehttp://en.wikipedia.org/wiki/Engineering_vehiclehttp://en.wikipedia.org/wiki/Fluid_powerhttp://en.wikipedia.org/wiki/Liquidhttp://en.wikipedia.org/wiki/Pressurized_gashttp://en.wikipedia.org/wiki/Pressurized_gas


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Comparison between Hydraulics and Pneumatics:

Hydraulics Pneumatics

Liquid does not absorb any of the suppliedenergy.

Reliability Pneumatic systems tend to have longoperating lives and require very littlemaintenance.

Because gas is compressible, the equipment is lesslikely to be damaged by shock. The gas inpneumatics absorbs excessive force, whereas thefluid of hydraulics directly transfers force.

Capable of moving much higher loads andproviding much higher forces due to theincompressibility.

Compressed Gas can be stored, allowing the useof machines when electrical power is lost.

No risk of explosion the slightest motion of theload releases the pressure.

But oils is considered flammable.

Very low chance of fire (compared to hydraulicoil).

But risks of explosion may occur .


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III)Electric:

Is simply any electric motor used.

Electrical actuators is considered the most used because they are easy to get and also for theirrelatively convenient cost .

Actuators can be also classified according to the output motion from them into

1- Linear2- Rotary

NoteActuators size and power (power to weight ratio)

are the main reasons for not making transformers in real life.

b) Power sink:

is simply the task required

Carrying loads Pushing objects Tracking or searching etc


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Main mechanical concepts and definitions

1) Force2) Pressure3) Torque& Moment 4) Stresses

5) Inertia

6) Velocity7) Acceleration 8) Discharge 9) Center of gravity

1) Force:is any influence that causes a free body to undergo a change in speed, a change in direction, or achange in shape.

2) Pressure:

Pressure is an effect which occurs when a force is applied on a surface. Pressure is the amount of forceacting on a unit area.

3) Tourque and moment:

is the tendency of a force to rotate an object about an axis, fulcrum, or pivot. Just as a force is a push

or a pull, a torque can be thought of as a twist.

Loosely speaking, torque is a measure of the turning force on an object such as a bolt or a flywheel.

For example, pushing or pulling the handle of a wrench connected to a nut or bolt produces a torque

(turning force) that loosens or tightens the nut or bolt.

4) Stresses:

stress is a measure of the internal forces acting within a deformable body. Quantitatively, it is a measure ofthe average force per unit area of a surface within the body on which internal forces act. These internalforces are a reaction to external forces applied on the body. Because the loaded deformable body is assumedto behave as a continuum, these internal forces are distributed continuously within the volume of thematerial body, and result in deformation of the body's shape. Beyond certain limits of material strength, thiscan lead to a permanent shape change or structural failure.
http://en.wikipedia.org/wiki/Free_bodyhttp://en.wikipedia.org/wiki/Leverhttp://en.wikipedia.org/wiki/Flywheelhttp://en.wikipedia.org/wiki/Forcehttp://en.wikipedia.org/wiki/Deformable_bodyhttp://en.wikipedia.org/wiki/Areahttp://en.wikipedia.org/wiki/Continuum_(theory)http://en.wikipedia.org/wiki/Strength_of_materialshttp://en.wikipedia.org/wiki/Strength_of_materialshttp://en.wikipedia.org/wiki/Continuum_(theory)http://en.wikipedia.org/wiki/Areahttp://en.wikipedia.org/wiki/Deformable_bodyhttp://en.wikipedia.org/wiki/Forcehttp://en.wikipedia.org/wiki/Flywheelhttp://en.wikipedia.org/wiki/Leverhttp://en.wikipedia.org/wiki/Free_body


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5) Inertia:

is the resistance of any physical object to a change in its state of motion or rest, or the tendency of anobject to resist any change in its motion. It is proportional to an object's mass.

6) Velocity:is the measurement of the rate and direction of change in the position of an object.

Note:

Rate of (x) : means the change of (x) w.r.t time.

Gradient of (x) : means the change of (x) w.r.t distance.

7) Acceleration:

is the rate of change of velocity over time .[1] In one dimension, acceleration is the rate at whichsomething speeds up or slows down
http://en.wikipedia.org/wiki/Masshttp://en.wikipedia.org/wiki/Position_vectorhttp://en.wikipedia.org/wiki/Velocityhttp://en.wikipedia.org/wiki/Acceleration#cite_note-0http://en.wikipedia.org/wiki/Acceleration#cite_note-0http://en.wikipedia.org/wiki/Acceleration#cite_note-0http://en.wikipedia.org/wiki/Rate_(mathematics)http://en.wikipedia.org/wiki/Rate_(mathematics)http://en.wikipedia.org/wiki/Acceleration#cite_note-0http://en.wikipedia.org/wiki/Velocityhttp://en.wikipedia.org/wiki/Position_vectorhttp://en.wikipedia.org/wiki/Mass


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8) Discharge:

the amount of fluid flowing

9) center of gravity:

is also named The center of mass or mass center is the mean location of all the mass in a system. In thecase of a rigid body, the position of the center of mass is fixed in relation to the body. In the case of aloose distribution of masses in free space, such as shot from a shotgun or the planets of the SolarSystem, the position of the center of mass is a point in space among them that may not correspond tothe position of any individual mass. The use of the mass center often allows the use ofsimplified equations of motion, and it is a convenient reference point for many other calculationsin physics,
http://en.wikipedia.org/wiki/Meanhttp://en.wikipedia.org/wiki/Masshttp://en.wikipedia.org/wiki/Rigid_bodyhttp://en.wikipedia.org/wiki/Free_spacehttp://en.wikipedia.org/wiki/Lead_shothttp://en.wikipedia.org/wiki/Shotgunhttp://en.wikipedia.org/wiki/Solar_Systemhttp://en.wikipedia.org/wiki/Solar_Systemhttp://en.wikipedia.org/wiki/Spacehttp://en.wikipedia.org/wiki/Equations_of_motionhttp://en.wikipedia.org/wiki/Physicshttp://en.wikipedia.org/wiki/Physicshttp://en.wikipedia.org/wiki/Equations_of_motionhttp://en.wikipedia.org/wiki/Spacehttp://en.wikipedia.org/wiki/Solar_Systemhttp://en.wikipedia.org/wiki/Solar_Systemhttp://en.wikipedia.org/wiki/Shotgunhttp://en.wikipedia.org/wiki/Lead_shothttp://en.wikipedia.org/wiki/Free_spacehttp://en.wikipedia.org/wiki/Rigid_bodyhttp://en.wikipedia.org/wiki/Masshttp://en.wikipedia.org/wiki/Mean


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Standards and CodesA standard is a set of specifications for parts, materials, or processes intended to achieve uniformity,efficiency, and a specified quality.

One of the important purposes of a standard is to place a limit on the number of items in thespecifications so as to provide a reasonable inventory of tooling, sizes, shapes, and varieties.

A code is a set of specifications for the analysis, design, manufacture, and construction of something.The purpose of a code is to achieve a specified degree of safety, efficiency, and performance or quality.It is important to observe that safety codes do not imply absolute safety. In fact, absolute safety isimpossible to obtain.

Aluminum Association (AA)

American Gear Manufacturers Association (AGMA)

American Institute of Steel Construction (AISC)

American Iron and Steel Institute (AISI)

American National Standards Institute (ANSI)5

ASM International6

American Society of Mechanical Engineers (ASME)

American Society of Testing and Materials (ASTM)

American Welding Society (AWS)

American Bearing Manufacturers Association (ABMA)7

British Standards Institution (BSI)

Industrial Fasteners Institute (IFI)

Institution of Mechanical Engineers (I. Mech. E.)

International Bureau of Weights and Measures (BIPM)

International Standards Organization (ISO)

National Institute for Standards and Technology (NIST)8

Society of Automotive Engineers (SAE)


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Design considerations1) Functionality

2) Noise

3) Strength/stress

4) Styling

5) Distortion/deflection/stiffness

6) Shape & Size

7) Wear & Corrosion

8) Control

9) Safety

10) Thermal properties

8) Reliability

10) Manufacturability

11) Lubrication

12) Cost & Marketability

13) Maintenance

14) Weight

15) Life

16) Remanufacturing/resource recovery

Note:

A simple journal bearing involves fluid flow, heat transfer, friction, energy transport, material

selection, thermo mechanical treatments, statistical descriptions, and so on.


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In this section we will discuss 2 of the design considerations.

1) Stress and Strength:

The survival of many products depends on how the designer adjusts the maximum stresses in acomponent to be less t han the components strength at specific locations of interest. The designer mustallow the maximum stress to be less than the strength by a sufficient margin so that despite the

uncertainties, failure is rare.

2) Uncertainty:

Uncertainties in machinery design abound. Examples of uncertainties concerning stress and strengthinclude

Composition of material and the effect of variation on properties. Variations in properties from place to place within a bar of stock.

Effect of processing locally, or nearby, on properties. Effect of nearby assemblies such as weldments and shrink fits on stress conditions. Effect of thermo mechanical treatment on properties. Intensity and distribution of loading. Validity of mathematical models used to represent reality. Intensity of stress concentrations. Influence of time on strength and geometry. Effect of corrosion. Effect of wear. Uncertainty as to the length of any list of uncertainties.


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Computational ToolsNote:

Because there are so many consideration and limitations in the real life using a simulation program is must to get a high accuracy.

Computer-aided design (CAD) software allows the development of three-dimensional (3-D) designs fromwhich conventional two-dimensional orthographic views with automatic dimensioning can be produced.

Manufacturing tool paths can be generated from the 3-D models, and in some cases, parts can be createddirectly from a 3-D database by usinga rapid prototyping and manufacturing method (stereolithography) paperless manufacturing!

Another advantage of a 3-D database is that it allows rapid and accurate calculations of mass properties suchas mass, location of the center of gravity, and mass moments of inertia. Other geometric properties such asareas and distances between points are likewise easily obtained. There are a great many CAD software

packages available such as Aries, AutoCAD, CadKey, I-Deas, Unigraphics, Solid Works, and ProEngineer,to name a few.

The term computer-aided engineering (CAE) generally applies to all computer related engineeringapplications. With this definition, CAD can be considered as a subset of CAE. Some computer software

packages perform specific engineering analysis and/or simulation tasks that assist the designer, but they arenot considered a tool for the creation of the design that CAD is. Such software fits into two categories:engineeringbasedand non-engineering-specific. Some examples of engineering-based software for mechanical engineeringapplications software that might also be integrated within a CAD system include finite-element analysis(FEA) programs for analysis of stress and deflection (see Chap. 19), vibration, and heat transfer (e.g., Algor,ANSYS, and MSC/NASTRAN); computational fluid dynamics (CFD) programs for fluid-flow analysis andsimulation (e.g., CFD++, FIDAP, and Fluent); and programs for simulation of dynamic force and motion inmechanisms (e.g., ADAMS, DADS, and Working Model).

Examples of non-engineering-specific computer-aided applications include software for word processing,spreadsheet software (e.g., Excel, Lotus, and Quattro-Pro), and mathematical solvers (e.g., Maple, MathCad,Matlab, Mathematica, and TKsolver).

Your instructor is the best source of information about programs that may be available to you and canrecommend those that are useful for specific tasks. One caution, however: Computer software is nosubstitute for the human thought process. You are the driver here;

the computer is the vehicle to assist you on your journey to a solution. Numbers generated by a computercan be far from the truth if you entered incorrect input, if you misinterpreted he application or the output ofthe program, if the program contained bugs, etc. It is your responsibility to assure the validity of the results,so be careful to check the application andresults carefully, perform benchmark testing by submitting problems with known solutions, and monitor thesoftware company and user-group newsletters.


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Materials properties

a) Atomic properties

Atomic mass Atomic number - applies to pure elements only Atomic weight - applies to individual isotopes or specific mixtures of isotopes of a given

element.

b) Chemical properties

Corrosion resistance Hygroscopy

pH Reactivity Specific internal surface area Surface energy Surface tension

c) Electrical properties

Conductivity Dielectric constant Dielectric strength Electrical conductivity Permeability Permittivity Piezoelectric constants

d) Mechanical properties

Compressive strength Density Ductility Fatigue limit Flexural modulus

Flexural strength Fracture toughness Hardness Poisson's ratio
http://en.wikipedia.org/wiki/Atomic_masshttp://en.wikipedia.org/wiki/Atomic_numberhttp://en.wikipedia.org/wiki/Atomic_weighthttp://en.wikipedia.org/wiki/Isotopehttp://en.wikipedia.org/wiki/Corrosionhttp://en.wikipedia.org/wiki/Hygroscopyhttp://en.wikipedia.org/wiki/PHhttp://en.wikipedia.org/wiki/Reactivity_(chemistry)http://en.wikipedia.org/wiki/BET_theoryhttp://en.wikipedia.org/wiki/Surface_energyhttp://en.wikipedia.org/wiki/Surface_tensionhttp://en.wikipedia.org/wiki/Conductivityhttp://en.wikipedia.org/wiki/Dielectric_constanthttp://en.wikipedia.org/wiki/Dielectric_strengthhttp://en.wikipedia.org/wiki/Electrical_conductivityhttp://en.wikipedia.org/wiki/Permeability_(electromagnetism)http://en.wikipedia.org/wiki/Permittivityhttp://en.wikipedia.org/wiki/Piezoelectrichttp://en.wikipedia.org/wiki/Compressive_strengthhttp://en.wikipedia.org/wiki/Densityhttp://en.wikipedia.org/wiki/Ductilityhttp://en.wikipedia.org/wiki/Fatigue_limithttp://en.wikipedia.org/wiki/Flexural_modulushttp://en.wikipedia.org/wiki/Flexural_strengthhttp://en.wikipedia.org/wiki/Fracture_toughnesshttp://en.wikipedia.org/wiki/Hardnesshttp://en.wikipedia.org/wiki/Poisson%27s_ratiohttp://en.wikipedia.org/wiki/Poisson%27s_ratiohttp://en.wikipedia.org/wiki/Hardnesshttp://en.wikipedia.org/wiki/Fracture_toughnesshttp://en.wikipedia.org/wiki/Flexural_strengthhttp://en.wikipedia.org/wiki/Flexural_modulushttp://en.wikipedia.org/wiki/Fatigue_limithttp://en.wikipedia.org/wiki/Ductilityhttp://en.wikipedia.org/wiki/Densityhttp://en.wikipedia.org/wiki/Compressive_strengthhttp://en.wikipedia.org/wiki/Piezoelectrichttp://en.wikipedia.org/wiki/Permittivityhttp://en.wikipedia.org/wiki/Permeability_(electromagnetism)http://en.wikipedia.org/wiki/Electrical_conductivityhttp://en.wikipedia.org/wiki/Dielectric_strengthhttp://en.wikipedia.org/wiki/Dielectric_constanthttp://en.wikipedia.org/wiki/Conductivityhttp://en.wikipedia.org/wiki/Surface_tensionhttp://en.wikipedia.org/wiki/Surface_energyhttp://en.wikipedia.org/wiki/BET_theoryhttp://en.wikipedia.org/wiki/Reactivity_(chemistry)http://en.wikipedia.org/wiki/PHhttp://en.wikipedia.org/wiki/Hygroscopyhttp://en.wikipedia.org/wiki/Corrosionhttp://en.wikipedia.org/wiki/Isotopehttp://en.wikipedia.org/wiki/Atomic_weighthttp://en.wikipedia.org/wiki/Atomic_numberhttp://en.wikipedia.org/wiki/Atomic_mass


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Shear modulus Shear strain Shear strength Softness Specific modulus

Specific weight Tensile strength Yield strength Young's modulus

Denisty:

The mass density or density of a material is defined as its mass per unit volume. The symbol mostoften used for density is (the Greek letter rho) . In some cases (for instance, in the United States oiland gas industry), density is also defined as its weight per unit volume ; [1]although, this quantity ismore properly called specific weight. Different materials usually have different densities, so density isan important concept regarding buoyancy, purity and packaging. Osmium and iridium are thedensest known metal elements at standard conditions for temperature and pressure but not thedensest materials.

Ductility:

Ductility is especially important in metalworking, as materials that crack or break under stress

cannot be manipulated using metal forming processes, such as hammering, rolling, and drawing. Malleable materials can be formed using stamping or pressing, whereas brittle metalsand plastics must be molded.

Hardness:

"Resistance of metal to plastic deformation, usually by indentation. However, the termmay also refer to stiffness or temper, or to resistance to scratching, abrasion, or cutting. Itis the property of a metal, which gives it the ability to resist being permanently, deformed(bent, broken, or have its shape changed), when a load is applied. The greater the hardnessof the metal, the greater resistance it has to deformation.

Shear strength:

in engineering is a term used to describe the strength of a material or component against the typeof yield or structural failure where the material or component fails in shear. A shear load is a forcethat tends to produce a sliding failure on a material along a plane that is parallel to the direction ofthe force. When a paper is cut with scissors, the paper fails in shear.

The yield strength or yield point of a material is defined in engineering and materials science asthe stress at which a material begins to deform plastically.

The specific weight (also known as the unit weight) is the weight per unit volume of a material. Thesymbol of specific weight is (the Greek letter Gamma) .
http://en.wikipedia.org/wiki/Shear_modulushttp://en.wikipedia.org/wiki/Shear_strainhttp://en.wikipedia.org/wiki/Shear_strengthhttp://en.wikipedia.org/wiki/Softnesshttp://en.wikipedia.org/wiki/Specific_modulushttp://en.wikipedia.org/wiki/Specific_weighthttp://en.wikipedia.org/wiki/Tensile_strengthhttp://en.wikipedia.org/wiki/Yield_strengthhttp://en.wikipedia.org/wiki/Young%27s_modulushttp://en.wikipedia.org/wiki/Masshttp://en.wikipedia.org/wiki/Volumehttp://en.wikipedia.org/wiki/Rho_(letter)http://en.wikipedia.org/wiki/Weighthttp://en.wikipedia.org/wiki/Volumehttp://en.wikipedia.org/wiki/Density#cite_note-0http://en.wikipedia.org/wiki/Density#cite_note-0http://en.wikipedia.org/wiki/Specific_weighthttp://en.wikipedia.org/wiki/Buoyancyhttp://en.wikipedia.org/wiki/Packaginghttp://en.wikipedia.org/wiki/Osmiumhttp://en.wikipedia.org/wiki/Iridiumhttp://en.wikipedia.org/wiki/Standard_conditions_for_temperature_and_pressurehttp://en.wikipedia.org/wiki/Metalworkinghttp://en.wikipedia.org/wiki/Hammerhttp://en.wikipedia.org/wiki/Rolling_(metalworking)http://en.wikipedia.org/wiki/Drawing_(metalworking)http://en.wikipedia.org/wiki/Stamping_(metalworking)http://en.wikipedia.org/wiki/Machine_presshttp://en.wikipedia.org/wiki/Plastichttp://en.wikipedia.org/wiki/Molding_(process)http://en.wikipedia.org/wiki/Engineeringhttp://en.wikipedia.org/wiki/Yield_(engineering)http://en.wikipedia.org/wiki/Structural_failurehttp://en.wikipedia.org/wiki/Shearing_(physics)http://en.wikipedia.org/wiki/Materialhttp://en.wikipedia.org/wiki/Engineeringhttp://en.wikipedia.org/wiki/Materials_sciencehttp://en.wikipedia.org/wiki/Stress_(physics)http://en.wikipedia.org/wiki/Plasticity_(physics)http://en.wikipedia.org/wiki/Weighthttp://en.wikipedia.org/wiki/Volumehttp://en.wikipedia.org/wiki/Gammahttp://en.wikipedia.org/wiki/Gammahttp://en.wikipedia.org/wiki/Volumehttp://en.wikipedia.org/wiki/Weighthttp://en.wikipedia.org/wiki/Plasticity_(physics)http://en.wikipedia.org/wiki/Stress_(physics)http://en.wikipedia.org/wiki/Materials_sciencehttp://en.wikipedia.org/wiki/Engineeringhttp://en.wikipedia.org/wiki/Materialhttp://en.wikipedia.org/wiki/Shearing_(physics)http://en.wikipedia.org/wiki/Structural_failurehttp://en.wikipedia.org/wiki/Yield_(engineering)http://en.wikipedia.org/wiki/Engineeringhttp://en.wikipedia.org/wiki/Molding_(process)http://en.wikipedia.org/wiki/Plastichttp://en.wikipedia.org/wiki/Machine_presshttp://en.wikipedia.org/wiki/Stamping_(metalworking)http://en.wikipedia.org/wiki/Drawing_(metalworking)http://en.wikipedia.org/wiki/Rolling_(metalworking)http://en.wikipedia.org/wiki/Hammerhttp://en.wikipedia.org/wiki/Metalworkinghttp://en.wikipedia.org/wiki/Standard_conditions_for_temperature_and_pressurehttp://en.wikipedia.org/wiki/Iridiumhttp://en.wikipedia.org/wiki/Osmiumhttp://en.wikipedia.org/wiki/Packaginghttp://en.wikipedia.org/wiki/Buoyancyhttp://en.wikipedia.org/wiki/Specific_weighthttp://en.wikipedia.org/wiki/Density#cite_note-0http://en.wikipedia.org/wiki/Volumehttp://en.wikipedia.org/wiki/Weighthttp://en.wikipedia.org/wiki/Rho_(letter)http://en.wikipedia.org/wiki/Volumehttp://en.wikipedia.org/wiki/Masshttp://en.wikipedia.org/wiki/Young%27s_modulushttp://en.wikipedia.org/wiki/Yield_strengthhttp://en.wikipedia.org/wiki/Tensile_strengthhttp://en.wikipedia.org/wiki/Specific_weighthttp://en.wikipedia.org/wiki/Specific_modulushttp://en.wikipedia.org/wiki/Softnesshttp://en.wikipedia.org/wiki/Shear_strengthhttp://en.wikipedia.org/wiki/Shear_strainhttp://en.wikipedia.org/wiki/Shear_modulus


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e) Thermal properties:

Autoignition temperature Binary phase diagram

Boiling point Coefficient of thermal expansion Critical temperature Curie point Emissivity Eutectic point Flammability Flash point

Glass transition temperature Heat of fusion Heat of vaporization Inversion temperature Melting point Phase diagram Pyrophoricity Specific heat Thermal conductivity Thermal diffusivity Thermal expansion Seebeck coefficient Triple point Vapor Pressure Vicat softening point
http://en.wikipedia.org/wiki/Autoignition_temperaturehttp://en.wikipedia.org/wiki/Binary_phase_diagramhttp://en.wikipedia.org/wiki/Boiling_pointhttp://en.wikipedia.org/wiki/Coefficient_of_thermal_expansionhttp://en.wikipedia.org/wiki/Critical_temperaturehttp://en.wikipedia.org/wiki/Curie_pointhttp://en.wikipedia.org/wiki/Emissivityhttp://en.wikipedia.org/wiki/Eutectic_pointhttp://en.wikipedia.org/wiki/Flammabilityhttp://en.wikipedia.org/wiki/Flash_pointhttp://en.wikipedia.org/wiki/Glass_transition_temperaturehttp://en.wikipedia.org/wiki/Heat_of_fusionhttp://en.wikipedia.org/wiki/Heat_of_vaporizationhttp://en.wikipedia.org/wiki/Inversion_temperaturehttp://en.wikipedia.org/wiki/Melting_pointhttp://en.wikipedia.org/wiki/Phase_diagramhttp://en.wikipedia.org/wiki/Pyrophoricityhttp://en.wikipedia.org/wiki/Specific_heathttp://en.wikipedia.org/wiki/Thermal_conductivityhttp://en.wikipedia.org/wiki/Thermal_diffusivityhttp://en.wikipedia.org/wiki/Thermal_expansionhttp://en.wikipedia.org/wiki/Thermopowerhttp://en.wikipedia.org/wiki/Triple_pointhttp://en.wikipedia.org/wiki/Vapor_Pressurehttp://en.wikipedia.org/wiki/Vicat_softening_pointhttp://en.wikipedia.org/wiki/Vicat_softening_pointhttp://en.wikipedia.org/wiki/Vapor_Pressurehttp://en.wikipedia.org/wiki/Triple_pointhttp://en.wikipedia.org/wiki/Thermopowerhttp://en.wikipedia.org/wiki/Thermal_expansionhttp://en.wikipedia.org/wiki/Thermal_diffusivityhttp://en.wikipedia.org/wiki/Thermal_conductivityhttp://en.wikipedia.org/wiki/Specific_heathttp://en.wikipedia.org/wiki/Pyrophoricityhttp://en.wikipedia.org/wiki/Phase_diagramhttp://en.wikipedia.org/wiki/Melting_pointhttp://en.wikipedia.org/wiki/Inversion_temperaturehttp://en.wikipedia.org/wiki/Heat_of_vaporizationhttp://en.wikipedia.org/wiki/Heat_of_fusionhttp://en.wikipedia.org/wiki/Glass_transition_temperaturehttp://en.wikipedia.org/wiki/Flash_pointhttp://en.wikipedia.org/wiki/Flammabilityhttp://en.wikipedia.org/wiki/Eutectic_pointhttp://en.wikipedia.org/wiki/Emissivityhttp://en.wikipedia.org/wiki/Curie_pointhttp://en.wikipedia.org/wiki/Critical_temperaturehttp://en.wikipedia.org/wiki/Coefficient_of_thermal_expansionhttp://en.wikipedia.org/wiki/Boiling_pointhttp://en.wikipedia.org/wiki/Binary_phase_diagramhttp://en.wikipedia.org/wiki/Autoignition_temperature


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Main mechanical components

Mechanisms Shafts Gears Chains and sprockets Pulleys and Belts Power screw Couplings Bearings

1) Mechanism:

device consisting of a piece of machinery; has moving parts that perform some function

Links : A mechanical linkage is an assembly of bodies connected together to manage forces and

movement. The movement of a body, or link, is studied using geometry so the link is considered to

be rigid. The connections between links are modeled as providing ideal movement, pure rotation or

sliding for example, and are called joints. A linkage modeled as a network of rigid links and ideal

joints is called a kinematic chain.

Linkages may be constructed from open chains, closed chains, or a combination of open and closed

chains. Each link in a chain is connected by a joint to one or more other links. Thus, a kinematic

chain can be modeled as a graph in which the links are vertices and the joints are paths, which is

called a linkage graph. The deployable mirror linkage is constructed from a series of rhombus or

scissor linkages.
http://www.thefreedictionary.com/mechanismhttp://www.thefreedictionary.com/mechanismhttp://en.wikipedia.org/wiki/Kinematic_chainhttp://en.wikipedia.org/wiki/File:Hebebuehne_Scissorlift.jpghttp://en.wikipedia.org/wiki/File:Hebebuehne_Scissorlift.jpghttp://en.wikipedia.org/wiki/Kinematic_chainhttp://www.thefreedictionary.com/mechanism


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Large scissor lift extended.

The movement of an ideal joint is generally associated with a subgroup of the group of Euclidean

displacements. The number of parameters in the subgroup is called th edegrees of freedom (DOF) of the

joint.

Mechanical linkages are usually designed to transform a given input force and movement into a desired

output force and movement. The ratio of the output force to the input force is known as the mechanicaladvantage of the linkage, while the ratio of the input speed to the output speed is known as the speed ratio.

The speed ratio and mechanical advantage are defined so they yield the same number in an ideal linkage.

A linkage designed to be stationary is called a structure.

Joints: Joints are used to connect parts of a mechanism or machine. These mechanical joints can betemporary or permanent depending on whether the connection needs to be removed frequently or notremoved at all. This determination is made by the designers and engineers of the machinery with themaintenance of the machinery taken into consideration.

Examples of joints

a) Bolted JointA bolted joint is the most common temporary joint used in the design of a system or machine. Likethe name of the joint states, the joint uses a bolt and screw to connect the two parts. The size of the

bolt is determined by the load required to ensure the connection is not severed during operation ofthe system. A bolt is inserted through a non-threaded hole drilled to the desired or engineered designand then a nut with washer is screwed on the end of the bolt. This type of joint allows themaintenance department to easily disassemble the joint when necessary.

b) Screw JointA screw joint is another temporary joint used to assemble two connections. This type of joint utilizesa screw only and is inserted through a drilled hole of one arm of the connection. The other arm orconnection point is drilled to the desired size and then tapped with a device that threads the hole tothe same size as the screw. The screw is then inserted and tightened down through the drilled armand into the tapped hole of the other arm of the connection. A screw joint is commonly used in soft

metal connections so wear can easily be repaired, such as in aluminum joints.

c) Welded JointA welded joint is a permanent joint that connects mechanical parts where disassembling is notnecessary. The two arms of the connection are designed to insert into each other and then weldedtogether. The type of weld is determined by the engineering department and is done by a certifiedwelder. The welded joint is used on hard metal or steel joints where heavy loads are expected to putstress on the connection. Welding the connection or mechanical joint does not allow for easydisassembly.

2) Shafts:
http://en.wikipedia.org/wiki/Degree_of_freedom_(mechanics)http://en.wikipedia.org/wiki/Mechanical_advantagehttp://en.wikipedia.org/wiki/Mechanical_advantagehttp://en.wikipedia.org/wiki/Mechanical_advantagehttp://en.wikipedia.org/wiki/Mechanical_advantagehttp://en.wikipedia.org/wiki/Degree_of_freedom_(mechanics)


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A shaft is a rotating member, usually of circular cross section, used to transmit power or motion. It provides the axis of rotation, or oscillation, of elements such as gears, pulleys, flywheels, cranks,sprockets, and the like and controls the geometry of their motion. An axle is a non-rotating member thatcarries no torque and is used to support rotating wheels, pulleys, and the like. The automotive axle is nota true axle; the term is a carry-over from the horse-and-buggy era, when the wheels rotated on non-rotating members. A non-rotating axle can readily be designed and analyzed as a static beam


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3) Gears:

Types of Gears

A) Spur gears: have teeth parallel to the axis of rotation and areused to transmit motion from one shaft to another, parallel, shaft. Of all types, the spur gear is the simplestand, for this reason, will be used to develop the primary kinematic relationships of the tooth form .

B) Helical gears: have teeth inclined to the axis of rotation. Helicalgears can be used for the same applications as spur gears and, when so used, are not as noisy, because ofthemore gradual engagement of the teeth duringmeshing. The inclined tooth also develops thrust loads and

bending couples, which are not present with spur gearing. Sometimes helical gears are used totransmitmotion between nonparallel shafts.

C) Bevel gears: have teeth formed on conical surfaces and areused mostly for transmitting motion between intersecting shafts. The figure actually illustrates straight-tooth

bevel gears. Spiral bevel gears are cut so the tooth is no longer straight, but forms a circular arc. Hypoidgears are quite similar to spiral bevel gears except that the shafts are offset and nonintersecting.


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D) Worms and worm gears: represent the fourth basic gear type.As shown, the worm resembles a screw. The direction of rotation of the worm gear, also called the wormwheel, depends upon the direction of rotation of the worm and upon whether the worm teeth are cut right-hand or left-hand. Worm-gear sets are also made so that the teeth of one or both wrap partly around theother. Such sets are called single enveloping and double-enveloping worm-gear sets. Worm-gear sets aremostly used when the speed ratios of the two shafts are quite high, say, 3 or more.

4) Chains and sprockets:


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A sprocket is a toothed wheel upon which a chain rides. Contrary to popular opinion, a sprocket isnot a gear.

Sprockets should be as large as possible given the application. The larger a sprocket is, the less theworking load for a given amount of transmitted power, allowing the use of a smaller-pitch chain.However, chain speeds should be kept under 1200 feet per minute.

Application:

Sprockets should be accurately aligned in a common vertical plane, with their axes parallel. Chain should bekept clean and well lubricated with a thin, light-bodied oil that will penetrate the small clearances between

pins and bushings.

Center distance should not be less than 1.5 times the diameter of the larger sprocket, nor less than 30 timesthe chain pitch, and should not exceed 60 times the chain pitch. Center distance should be adjustable - onechain pitch is sufficient - and failing this an idler sprocket should be used to adjust tension. A little slack isdesirable, preferably on the bottom side of the drive.

The chain should wrap at least 120 around the drive sprocket, which requires a ratio of no more than 3.5 to1; for greater ratios, an idler sprocket may be required to increase wrap angle.

Chain Construction:

Chains have a surprising number of parts. The roller turns freely on the bushing , which is attached on eachend to the inner plate . A pin passes through the bushing, and is attached at each end to the outer plate .Bicycle chains omit the bushing, instead using the circular ridge formed around the pin hole of the inner

plate.


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Selecting a Chain:

Two factors determine the selection of a chain; the working load and the rpm of the smaller sprocket. Theworking load sets a lower limit on pitch, and the speed sets an upper limit.

5) Pulleys and belts

A belt is a loop of flexible material used to link two or more rotating shafts mechanically. Belts may be used

as a source of motion, to transmit power efficiently, or to track relative movement. Belts are loopedover pulleys. In a two pulley system, the belt can either drive the pulleys in the same direction, or the beltmay be crossed, so that the direction of the shafts is opposite. As a source of motion, a conveyor belt is oneapplication where the belt is adapted to continually carry a load between two points.
http://en.wikipedia.org/wiki/Drive_shafthttp://en.wikipedia.org/wiki/Transmission_(mechanics)http://en.wikipedia.org/wiki/Pulleyhttp://en.wikipedia.org/wiki/Conveyor_belthttp://en.wikipedia.org/wiki/Conveyor_belthttp://en.wikipedia.org/wiki/Pulleyhttp://en.wikipedia.org/wiki/Transmission_(mechanics)http://en.wikipedia.org/wiki/Drive_shaft


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Note:

Pulleys and belts have two uses; to increase or reduce speed or torque, or to transfer power from one shaft toanother. If the transfer of power is all you need, then two pulleys of the same diameter will do the trick. Butmost of the time you'll also want to take the opportunity to trade speed for torque, or vice versa. This is done

by using pulleys of different pitch diameters.

The pitch diameter of a pulley is not the outside diameter. Or the inside diameter. In fact, the pitch diameteris very difficult to measure directly. If you cut a belt and look at the end, you'll see a row of fibers near theoutside surface. This is the tension carrying part of the belt; the rest of the belt exists only to carry the forcesfrom the pulley to and from these fibers. The pitch diameter of any pulley is measured at these fibers. If youthink about this for a moment, you'll see that the pitch diameter of a pulley depends not just on the pulleyitself, but on the width of the belt. If you put a B series belt on an A series pulley, it will ride higher thanusual, increasing the effective pitch diameter.

The ratio of the pitch diameters is called the drive ratio , the ratio by which torque is increased and speed isdecreased, or vice versa. Power is the product of speed and force, or in the case of things that spin, speedand torque. Pulleys do not effect power ; when they increase torque, it is at the expense of speed, and viceversa.

V-belts are not 100% efficient, however. While they transfer torque effectively, they loose a bit of speed asthe belt stretches under load.

Belt Length

The easy way to measure the circumference of a belt is to roll it along the wall, measuring the distanceyou've traveled when you get back to the same point on the belt. Subtract two inches to get the insidecircumference.

If you don't have a belt, just the pulleys installed on the machine, you can run a string around the pulleys andmeasure that. If you don't have access to the machine, you can use a formula so royally obnoxious that Iwon't include it here, as the above calculator will do it for you. (If you insist, you can view the source codeof this document and find it in the TensionCalc Javascript function).

It is important to remember when designing belt drives that belts come in discrete lengths, and pulleys comein discrete pitch diameters; you cannot just arbitrarily select dimensions hope to find such components.

If you're like me, you often scrounge up a belt and some pulleys, and then try to figure out the centerdistance. The easy way, of course, is to lay them out on the work bench and measure it. If you can't do that,

just enter the pulley sizes into the above calculator, and reiteratively enter values for center distance untilyou manage to hit on the right belt length. It's a kludgy way to do it, but if you saw the formula, you'd knowwhy I didn't want to solve it for center distance.


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6) Power screw:

Power Screws are used for providing linear motion in a smooth uniform manner. They are linear actuatorsthat transform rotary motion into linear motion. Power screws are are generally based on Acme , Square,and Buttress threads. Ball screws are a type of power screw. Efficiencies of between 30% and 70% areobtained with conventional power screws. Ball screws have efficiencies of above 90%.Power Screws are used for the following three reasons

To obtain high mechanical advantage in order to move large loads with minimum effort. e.g ScrewJack.

To generate large forces e.g A compactor press. To obtain precise axial movements e.g. A machine tool lead screw.

Square Form :

This form is used for power/force transmission i.e. linear jacks, clamps. The friction is low and thereis no radial forces imposed on the mating nuts. The square thread is the most efficient conventional

power screw form. It is the most difficult form to machine. It is not very compatible for using splitnuts-as used on certain machine tool system for withdrawing the tool carriers

Buttress Form :

A strong low friction thread. However it is designed only to take large loads in on direction. For agiven size this is the strongest of the thread forms. When taking heavy loads on the near verticalthread face this thread is almost as efficient as a square thread form.


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7) Couplings :

A coupling is a device used to connect two shafts together at their ends for the purpose of transmitting

power. Couplings do not normally allow disconnection of shafts during operation, however there are torque

limiting couplings which can slip or disconnect when some torque limit is exceeded.

The primary purpose of couplings is to join two pieces of rotating equipment while permitting some degree

of misalignment or end movement or both. By careful selection, installation and maintenance of couplings,substantial savings can be made in reduced maintenance costs and downtime.

Shaft couplings are used in machinery for several purposes, the most common of which are the following .[1]

To provide for the connection of shafts of units that are manufactured separately such as a motor and

generator and to provide for disconnection for repairs or alternations. To provide for misalignment of the shafts or to introduce mechanical flexibility. To reduce the transmission of shock loads from one shaft to another.

To introduce protection against overloads. To alter the vibration characteristics of rotating units.

Types:

A) Rigid:A rigid coupling is a unit of hardware used to join two shafts within a motor or mechanical system. It may

be used to connect two separate systems, such as a motor and a generator, or to repair a connection within a

single system. A rigid coupling may also be added between shafts to reduce shock and wear at the point

where the shafts meet.

B) Flexible:

Flexible couplings are used to transmit torque from one shaft to another when the two shafts are slightly

misaligned. Flexible couplings can accommodate varying degrees of misalignment up to 3. In addition to

allowing for misalignment, flexible couplings can also be used for vibration damping or noise reduction.

Flexible couplings are designed to transmit torque while permitting some radial, axial, and angular

misalignment. Flexible couplings can accommodate angular misalignment up to a few degrees and some

parallel misalignment.
http://en.wikipedia.org/wiki/Torque_limiterhttp://en.wikipedia.org/wiki/Torque_limiterhttp://en.wikipedia.org/wiki/Coupling#cite_note-0http://en.wikipedia.org/wiki/Coupling#cite_note-0http://en.wikipedia.org/wiki/Coupling#cite_note-0http://en.wikipedia.org/wiki/Torquehttp://en.wikipedia.org/wiki/Degree_(angle)http://en.wikipedia.org/wiki/Degree_(angle)http://en.wikipedia.org/wiki/Torquehttp://en.wikipedia.org/wiki/Coupling#cite_note-0http://en.wikipedia.org/wiki/Torque_limiterhttp://en.wikipedia.org/wiki/Torque_limiter

[course] robotics - notes - ieeealexsb

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