Last Minute Cram Review Last Minute Cram Hydrogen

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Last Minute Cram + Review

Last Minute Cram + Review

Last Minute Cram üHydrogen Fuel Cells üFluid Power üProbability üMaterial Classification üManufacturing Processes

Last Minute Cram üHydrogen Fuel Cells üFluid Power üProbability üMaterial Classification üManufacturing Processes

Trends in the Use of Fuel

Trends in the Use of Fuel

A Simple PEM Fuel Cell Hydrogen + Oxygen Electricity + Water

A Simple PEM Fuel Cell Hydrogen + Oxygen Electricity + Water

PEM Fuel Cell Electrochemical Reactions Anode: H 2 2 H+ + 2 e- (oxidation)

PEM Fuel Cell Electrochemical Reactions Anode: H 2 2 H+ + 2 e- (oxidation) Cathode: 1/2 O 2 + 2 e- + 2 H+ H 2 O (l) (reduction) Overall Reaction: H 2 + 1/2 02 H 2 O (l) ΔH = - 285. 8 k. J/mole

The Benefits of Fuel Cells Clean Modular Quiet Benefits of Fuel Cells Safe Sustainable

The Benefits of Fuel Cells Clean Modular Quiet Benefits of Fuel Cells Safe Sustainable Efficient

Fluid Power Definitions Fluid Power The use of a fluid to transmit power from

Fluid Power Definitions Fluid Power The use of a fluid to transmit power from one location to another Hydraulics The use of a liquid flowing under pressure to transmit power from one location to another Pneumatics The use of a gas flowing under pressure to transmit power from one location to another

Basic Fluid Power Components Reservoir / Receiver – Stores fluid Fluid Conductors – Pipe,

Basic Fluid Power Components Reservoir / Receiver – Stores fluid Fluid Conductors – Pipe, tube, or hose that allows for flow between components Pump / Compressor – Converts mechanical power to fluid power Valve – Controls direction and amount of flow Actuators – Converts fluid power to mechanical power

Pascal’s Law Pressure exerted by a confined fluid acts undiminished equally in all directions.

Pascal’s Law Pressure exerted by a confined fluid acts undiminished equally in all directions. Pressure: The force per unit area exerted by a fluid against a surface Symbol Definition Example Unit p Pressure lb/in. 2 F Force lb A Area in. 2

Pascal’s Law Example How much pressure can be produced with a 3 in. diameter

Pascal’s Law Example How much pressure can be produced with a 3 in. diameter (d) cylinder and 50 lb of force? d = 3 in. F = 50 lb p=? A=?

Boyle’s Law The volume of a gas at constant temperature varies inversely with the

Boyle’s Law The volume of a gas at constant temperature varies inversely with the pressure exerted on it. p 1 (V 1) = p 2 (V 2) NASA Symbol Definition Example Unit V Volume in. 3

Boyle’s Law Example A cylinder is filled with 40. in. 3 of air at

Boyle’s Law Example A cylinder is filled with 40. in. 3 of air at a pressure of 60. psi. The cylinder is compressed to 10. in. 3. What is the resulting absolute pressure? p 1 = 60. lb/in. 2 V 1 = 40. in. 3 p 2 = ? V 2 = 10. in. 3 Convert p 1 to absolute pressure. p 1 = 60. lb/in. 2 + 14. 7 lb/in. 2 = 74. 7 lb/in. 2

Bernoulli’s Principle Conservation of Energy: An increase in velocity results in a decrease in

Bernoulli’s Principle Conservation of Energy: An increase in velocity results in a decrease in pressure. Likewise, a decrease in velocity results in an increase in pressure.

Mechanical Advantage National Fluid Power Association & Fluid Power Distributors Association

Mechanical Advantage National Fluid Power Association & Fluid Power Distributors Association

Mechanical Advantage Example A force of 100. lb is applied to the input cylinder

Mechanical Advantage Example A force of 100. lb is applied to the input cylinder of the hydraulic press seen below. What is the pressure in the system? How much force can the output cylinder lift? What is the mechanical advantage of the system? Fin = 100. lb din = 4. 0 in. Fin = 100. lb Fout = ? din = 4. 0 in. dout = 12. 0 in. Ain = ? Aout = ? p=? MA = ? dout = 12. 0 in.

Mechanical Advantage Example Find the area of each cylinder. Fin=100. lb Ain=? Fout=? Aout=?

Mechanical Advantage Example Find the area of each cylinder. Fin=100. lb Ain=? Fout=? Aout=? Rin=2. 0 in. p=? MA=? Rout =6. 00 in.

Mechanical Advantage Example Find the pressure in the system. Fin=100. lb Ain=12. 57 in.

Mechanical Advantage Example Find the pressure in the system. Fin=100. lb Ain=12. 57 in. 2 Fout=? Rin=2. 0 in. Aout=113. 10 in. 2 Rout=6. 00 in. p=? MA=?

Mechanical Advantage Example Find the force that the output cylinder can lift. Fin=100. lb

Mechanical Advantage Example Find the force that the output cylinder can lift. Fin=100. lb Fout=? Rin=2. 0 in. Ain=12. 57 in. 2 Aout=113. 10 in. 2 Rout =6. 00 in. p=7. 955 lb/in. 2 MA=?

Mechanical Advantage Example Find the mechanical advantage of the system. Fin=100. lb Fout=900. 28

Mechanical Advantage Example Find the mechanical advantage of the system. Fin=100. lb Fout=900. 28 lb Rin=2. 0 in. Ain=12. 57 in. 2 Aout=113. 10 in. 2 Rout =6. 00 in. p=7. 955 lb/in. 2 MA=?

Relative Frequency The number of times an event will occur divided by the number

Relative Frequency The number of times an event will occur divided by the number of opportunities = Relative frequency of outcome x = Number of events with outcome x n = Total number of events Expressed as a number between 0 and 1 fraction, percent, decimal, odds Total frequency of all possible events totals 1

Probability What is the probability of a tossed coin landing heads up? How many

Probability What is the probability of a tossed coin landing heads up? How many desirable outcomes? 1 How many possible outcomes? 2 Probability Tree What is the probability of the coin landing tails up?

Probability What is the probability of tossing a coin twice and it landing heads

Probability What is the probability of tossing a coin twice and it landing heads up both times? How many desirable outcomes? 1 HH HT How many possible outcomes? 4 TH TT

3 rd Probability What is the probability of tossing a coin three times and

3 rd Probability What is the probability of tossing a coin three times and it landing 1 heads up exactly two times? How many desirable outcomes? 3 st How many possible outcomes? 8 2 nd HHH HHT HTH HTT THH THT TTH TTT

Probability AND (Multiplication) Independent events occurring simultaneously Product of individual probabilities If events A

Probability AND (Multiplication) Independent events occurring simultaneously Product of individual probabilities If events A and B are independent, then the probability of A and B occurring is: P(A and B) = PA∙PB

Probability AND (Multiplication) What is the probability of rolling a 4 on a single

Probability AND (Multiplication) What is the probability of rolling a 4 on a single die? How many desirable outcomes? 1 How many possible outcomes? 6 What is the probability of rolling a 1 on a single die? How many desirable outcomes? 1 How many possible outcomes? 6 What is the probability of rolling a 4 and then a 1 in sequential rolls?

OR (Addition) Probability Independent events occurring individually Sum of individual probabilities If events A

OR (Addition) Probability Independent events occurring individually Sum of individual probabilities If events A and B are mutually exclusive, then the probability of A or B occurring is: P(A or B) = PA + PB

Probability OR (Addition) What is the probability of rolling a 4 on a single

Probability OR (Addition) What is the probability of rolling a 4 on a single die? How many desirable outcomes? 1 How many possible outcomes? 6 What is the probability of rolling a 1 on a single die? How many desirable outcomes? 1 How many possible outcomes? 6 What is the probability of rolling a 4 or a 1 on a single die?

NOT Probability Independent event not occurring 1 minus the probability of occurrence P =

NOT Probability Independent event not occurring 1 minus the probability of occurrence P = 1 - P(A) What is the probability of not rolling a 1 on a die?

Probability Two cards are dealt from a shuffled deck. What is the probability that

Probability Two cards are dealt from a shuffled deck. What is the probability that the first card is an ace and the second card is a face card or a ten? How many cards are in a deck? 52 How many aces are in a deck? 4 How many face cards are in deck? 12 How many tens are in a deck? 4

Probability What is the probability that the first card is an ace? Since the

Probability What is the probability that the first card is an ace? Since the first card was NOT a face, what is the probability that the second card is a face card? Since the first card was NOT a ten, what is the probability that the second card is a ten?

Probability Two cards are dealt from a shuffled deck. What is the probability that

Probability Two cards are dealt from a shuffled deck. What is the probability that the first card is an ace and the second card is a face card or a ten? If the first card is an ace, what is the probability that the second card is a face card or a ten? 31. 37%

Material Classification Based upon material composition and distinguishable properties Common material classification categories: Metallic

Material Classification Based upon material composition and distinguishable properties Common material classification categories: Metallic Materials Ceramic Materials Organic Materials Polymeric Materials Composite Materials

Metallic Materials Distinguishing Characteristics Pure metal elements (Not commonly found or used) Metal element

Metallic Materials Distinguishing Characteristics Pure metal elements (Not commonly found or used) Metal element compounds (alloy) (Commonly used due to the engineered properties of the compound) Thermal and electrical conductors Mechanical properties include strength and plasticity

Ceramic Materials Distinguishing Characteristics Compounds consisting of metal and nonmetal elements Thermal and electrical

Ceramic Materials Distinguishing Characteristics Compounds consisting of metal and nonmetal elements Thermal and electrical insulators Mechanical properties include high strength at high temperatures and brittleness

Ceramic Materials Applications Clay – Shaped, dried, and fired inorganic material Examples: Brick, tile,

Ceramic Materials Applications Clay – Shaped, dried, and fired inorganic material Examples: Brick, tile, sewer pipe, chimney flue, china, porcelain, etc. Refractory – Designed to provide acceptable mechanical or chemical properties while at high temperatures Example: Space shuttle allsilica insulating tiles

Ceramic Materials Applications Electrical Resistors – Create desired voltage drops and limit current Thermistors

Ceramic Materials Applications Electrical Resistors – Create desired voltage drops and limit current Thermistors – Application of heat regulates current flow Rectifiers – Allow current to flow in one direction Heating elements for furnaces

Organic Materials Distinguishing Characteristics Are or were once living organisms Consist of mostly carbon

Organic Materials Distinguishing Characteristics Are or were once living organisms Consist of mostly carbon and hydrogen Genetically alterable Renewable Sustainable

Polymeric Materials Distinguishing Characteristics Compounds consist of mostly organic elements Low density Mechanical properties

Polymeric Materials Distinguishing Characteristics Compounds consist of mostly organic elements Low density Mechanical properties include flexibility and elasticity Polymeric Subgroups Plastics Elastomers

Polymeric Materials Plastics Thermoplastic Formed into a desired shape by applying heat and pressure

Polymeric Materials Plastics Thermoplastic Formed into a desired shape by applying heat and pressure and being cooled May be heated and remolded Thermosetting Formed into a desired shape by applying heat and pressure and being cooled May not be heated and remolded

Polymeric Materials Elastomers Natural or synthetic material Can be stretched 200 percent of their

Polymeric Materials Elastomers Natural or synthetic material Can be stretched 200 percent of their length at room temperature and can return quickly to original length after force is released Vulcanization Chemical process used to form strong bonds between adjacent polymers to produce a tough, strong, hard rubber (automobile tires)

Composite Materials Distinguishing Characteristics Composed of more then one material Designed to obtain desirable

Composite Materials Distinguishing Characteristics Composed of more then one material Designed to obtain desirable properties from each individual material

Composite Materials Layer Composites – Alternate layers of materials bonded together Particulate Composites –

Composite Materials Layer Composites – Alternate layers of materials bonded together Particulate Composites – Discrete particles of one material surrounded by a matrix of another material Fiber-Reinforced Composites –Composed of continuous or discontinuous fibers embedded in a matrix of another material

Basic Manufacturing Processes Casting and Foundry Forming or Metalworking Machining Joining and Assembly Rapid

Basic Manufacturing Processes Casting and Foundry Forming or Metalworking Machining Joining and Assembly Rapid Prototyping Other

Casting and Foundry Processes In one step raw materials are transformed into a desirable

Casting and Foundry Processes In one step raw materials are transformed into a desirable shape Parts require finishing processes Excess material is recyclable ©i. Stockphoto. com

Forming and Metalworking Processes Rolling – Material passes through a series of rollers, reducing

Forming and Metalworking Processes Rolling – Material passes through a series of rollers, reducing its thickness with each pass Forging – Material is shaped by the controlled application of force (blacksmith)

Forming and Metalworking Processes Extrusion – Material is compressed and forced through a die

Forming and Metalworking Processes Extrusion – Material is compressed and forced through a die to produce a uniformed cross section Wire, rod, and tube drawing – Material is pulled through a die to produce a uniformed cross section ©i. Stockphoto. com

Machining Processes Turning Processes Operations that create cylindrical parts Work piece rotates as cutting

Machining Processes Turning Processes Operations that create cylindrical parts Work piece rotates as cutting tool is fed into the work ©i. Stockphoto. com

Machining Processes Milling Processes Operations that create flat or curved surfaces by progressively removing

Machining Processes Milling Processes Operations that create flat or curved surfaces by progressively removing material Cutting tools rotate as the work piece is secured and fed into the tool

Machining Processes Drilling Processes Operations that create holes Cutting tools rotate and are fed

Machining Processes Drilling Processes Operations that create holes Cutting tools rotate and are fed into nonmoving secured work pieces

Machining Processes Shearing Processes Operations that break unwanted material away from the part A

Machining Processes Shearing Processes Operations that break unwanted material away from the part A material is placed between a stationary and movable surface. The movable surface (blade, die, or punch) applies a force to the part that shears away the unwanted material.

Machining Processes Abrasive Machining Processes Operations in which small particles of materials (abrasives) remove

Machining Processes Abrasive Machining Processes Operations in which small particles of materials (abrasives) remove small chips of material upon contact Drum, disc, and belt sanders; surface, vertical and horizontal spindle; disc grinders; media blaster; tumblers

Joining and Assembly Processes Can you think of a product with only one part?

Joining and Assembly Processes Can you think of a product with only one part? Most products consist of multiple parts that are assembled to form a finished product. Typical assembly processes include: Mechanical fastening; soldering and brazing, welding; adhesive bonding

Rapid Prototyping – Additive Process Finished parts can be field tested depending upon building

Rapid Prototyping – Additive Process Finished parts can be field tested depending upon building material Created parts can be used to create a mold Modifications to design can be implemented quickly

Plastics Manufacturing Processes Injection Molding Heated plastic is forced by a movable plunger through

Plastics Manufacturing Processes Injection Molding Heated plastic is forced by a movable plunger through a nozzle and then into a mold. The material fills the mold and then is cooled. Most widely used high-volume production process

Review üSimple Machines üEnergy & Power üThermodynamics üMaterial Testing üStatics üMachine Control (still fresh

Review üSimple Machines üEnergy & Power üThermodynamics üMaterial Testing üStatics üMachine Control (still fresh – not in review) üKinematics (still fresh – not in review)

Lever Moment Calculation Effort 4 in. 15 15 lb lbs Resistance ? 30 lb

Lever Moment Calculation Effort 4 in. 15 15 lb lbs Resistance ? 30 lb Using what you know regarding static equilibrium, calculate the unknown distance from the fulcrum to the resistance force. Static equilibrium: Effort Moment = Resistance Moment 60 in. -lb = 30 lb x DR 60 in. -lb /30 lb = DR DR = 2 in.

Lever IMA vs AMA The ratio of applied resistance force to applied effort force

Lever IMA vs AMA The ratio of applied resistance force to applied effort force 5. 5 in. 2. 25 in. 32 lb 16 lb Effort What is the AMA of the lever above? Resistance AMA = 2: 1 Why is the IMA larger than the AMA? What is the IMA of the lever above? IMA = 2. 44: 1

1 st Class Lever Fulcrum is located between the effort and the resistance force

1 st Class Lever Fulcrum is located between the effort and the resistance force Effort and resistance forces are applied to the lever arm in the same direction Only class of lever that can have a MA greater than or less than 1 Resistance Effort MA =1 Effort Resistance MA <1 Resistance Effort MA >1

2 nd Class Lever Fulcrum is located at one end of the lever Resistance

2 nd Class Lever Fulcrum is located at one end of the lever Resistance force is located between the fulcrum and the effort force Resistance force and effort force are in opposing directions Always has a mechanical advantage >1 Resistance Effort

3 rd Class Lever Fulcrum is located at one end of the lever Effort

3 rd Class Lever Fulcrum is located at one end of the lever Effort force is located between the fulcrum and the resistance Resistance force and effort force are in opposing directions Always has a mechanical advantage < 1 Resistance Effort

Efficiency In a machine, the ratio of useful energy output to the total energy

Efficiency In a machine, the ratio of useful energy output to the total energy input, or the percentage of the work input that is converted to work output The ratio of AMA to IMA What is the efficiency of the lever on the previous slide? Click to return to previous slide AMA = 2: 1 IMA = 2. 44: 1 No machine is 100% efficient.

Wheel & Axle IMA Ǿ 6 in. Ǿ 20 in. Both effort and resistance

Wheel & Axle IMA Ǿ 6 in. Ǿ 20 in. Both effort and resistance forces will travel in a circle if unopposed. Circumference = 2 pr or πd DE = π [Diameter of effort (wheel or axle)] DR = π [Diameter resistance (wheel or axle)] π (effort diameter) IMA = ___________ π (resistance diameter) What is the IMA of the wheel above if the axle is driving the wheel? 6 in. / 20 in. =. 3: 1 = 3: 10 What is the IMA of the wheel above if the wheel is driving the axle? 20 in. / 6 in. = 3. 33: 1

Wheel & Axle AMA Ǿ 6 in. Ǿ 20 in. 200 lb Use the

Wheel & Axle AMA Ǿ 6 in. Ǿ 20 in. 200 lb Use the wheel and axle assembly illustration to the right to solve the following. 70 lb What is the AMA if the wheel is driving the axle? 200 lb/70 lb = 2. 86: 1 What is the efficiency of the wheel and axle assembly? = 85. 9%

Pulley IMA Fixed Pulley - 1 st class lever with an IMA of 1

Pulley IMA Fixed Pulley - 1 st class lever with an IMA of 1 - Changes the direction of force 10 lb 5 lb Movable Pulley - 2 nd class lever with an IMA of 2 - Force directions stay constant 10 lb

Pulley AMA What is the AMA of the pulley system on the right? AMA

Pulley AMA What is the AMA of the pulley system on the right? AMA = 3. 48: 1 What is the efficiency of the pulley system on the right? % Efficiency = 230 lb 800 lb = 87%

Inclined Plane IMA. 0 15 ft DE = Distance traveled by the effort =

Inclined Plane IMA. 0 15 ft DE = Distance traveled by the effort = L DR = Distance traveled by the resistance = H What is the IMA of the inclined plane above? IMA = 15. 0 ft / 4. 0 ft = 3. 75 = 3. 8: 1 4. 0 ft

Wedge IMA DE = Distance traveled by the effort = L L 10. 0

Wedge IMA DE = Distance traveled by the effort = L L 10. 0 in. H 3. 0 in. DR = Distance traveled by the resistance = H What is the IMA of the wedge on the right? IMA = 10. 0 in. / 3. 0 in. = 3. 33 = 3. 3: 1

Screw IMA 1/4 20 NC DE = One rotation of the effort arm =

Screw IMA 1/4 20 NC DE = One rotation of the effort arm = Circumference DR = Linear distance traveled during one rotation of the effort arm = Pitch What is the IMA of the screw above if effort is applied by an 8. 0 in. long wrench?

Gear Ratios Equations to know GR = Gear Ratio

Gear Ratios Equations to know GR = Gear Ratio

Gear Ratios: Simple Gear Trains Idler gears don’t affect GR! What is the TOTAL

Gear Ratios: Simple Gear Trains Idler gears don’t affect GR! What is the TOTAL gear train gear ratio? If gear A and D were directly connected to each other, what would the resulting gear ratio be? What would the total gear ratio be if the last gear had 40 teeth? or

Compound Gear Ratios D B A C 20 T 10 T 40 T 50

Compound Gear Ratios D B A C 20 T 10 T 40 T 50 T What is the gear ratio between gear A and B? What is the gear ratio between gear C and D? What is the gear ratio of the entire gear train?

d = diameter ω = angular velocity (speed) out in Equations 2 in. Pulley

d = diameter ω = angular velocity (speed) out in Equations 2 in. Pulley and Belt Systems t = torque

Sprocket and Chain Systems 1. 5 in. in n = number of teeth d

Sprocket and Chain Systems 1. 5 in. in n = number of teeth d = diameter ω = angular velocity (speed) 3 in. out τ = torque

Energy Sources Energy: The ability to do work Energy sources are defined as –

Energy Sources Energy: The ability to do work Energy sources are defined as – Nonrenewable – Renewable – Inexhaustible The SUN is the original source of almost all energy sources on Earth.

Work Example A student lifts a 50 pound (lb) ball 4 feet (ft) in

Work Example A student lifts a 50 pound (lb) ball 4 feet (ft) in 5 seconds (s). How many joules of work did the student complete? Convert English units to SI units Solve for Work

Power Example A student lifts a 50. 0 pound (lb) ball 4. 00 feet

Power Example A student lifts a 50. 0 pound (lb) ball 4. 00 feet (ft) in 5. 00 seconds (s). How many watts of power are used to lift the ball? Work = 271. 45 J

Types of Power Electrical Power Uses electrical energy to do work Mechanical Power Uses

Types of Power Electrical Power Uses electrical energy to do work Mechanical Power Uses mechanical energy to do work (linear, rotary) Fluid Power Uses energy transferred by liquids (hydraulic) and gases (pneumatic)

Conductors and Insulators Conductors Insulators Electrons flow easily between atoms Electron flow is difficult

Conductors and Insulators Conductors Insulators Electrons flow easily between atoms Electron flow is difficult between atoms 1 -3 valence electrons in outer orbit 5 -8 valence electrons in outer orbit Examples: Silver, Examples: Mica, Glass, Copper, Gold, Aluminum Quartz

Measuring Current Set multimeter to the proper ADC range. Circuit flow must go through

Measuring Current Set multimeter to the proper ADC range. Circuit flow must go through the meter. Switch Battery Resistor Light

Measuring Resistance Set multimeter to the proper Ohms range. Measure across the component being

Measuring Resistance Set multimeter to the proper Ohms range. Measure across the component being tested. Power must be off or removed from the circuit. Switch Battery Resistor Light

Ohm’s Law Current in a resistor varies in direct proportion to the voltage applied

Ohm’s Law Current in a resistor varies in direct proportion to the voltage applied to it and is inversely proportional to the resistor’s value The mathematical relationship between current, voltage, and resistance If you know 2 of the 3 quantities, you can solve for the third. Quantities Abbreviations Units Symbols Voltage V Volts V Current I Amperes A Resistance R Ohms Ω V=IR I=V/R R=V/I

Circuit Configuration Components in a circuit can be connected in one of two ways.

Circuit Configuration Components in a circuit can be connected in one of two ways. Series Circuits • Components are connected end-to-end. • There is only a single path for current to flow. Parallel Circuits • Both ends of the components are connected together. • There are multiple paths for current to flow. Components (i. e. , resistors, batteries, capacitors, etc. )

Series Circuits Characteristics of a series circuit • The current flowing through every series

Series Circuits Characteristics of a series circuit • The current flowing through every series component is equal. • The total resistance (RT) is equal to the sum of all of the resistances (i. e. , R 1 + R 2 + R 3). • The sum of all voltage drops (V 1 + V 2 + V 3) is equal to the total applied voltage (VT). This is called Kirchhoff’s Voltage V Law. IT + VR 1 - + + VR 2 T - - RT - + VR 3

Parallel Circuits Characteristics of a Parallel Circuit • The voltage across every parallel component

Parallel Circuits Characteristics of a Parallel Circuit • The voltage across every parallel component is equal. • The total resistance (RT) is equal to the reciprocal of the sum of the reciprocal: • The sum of all of the currents in each branch (IR 1 + IR 2 + IR 3) is equal to the total current (IT). This is called Kirchhoff’s Current Law. I T + + VR 1 VT VR 2 - - RT + + VR 3 - -

Electrical Power Electrical power is directly related to the amount of current and voltage

Electrical Power Electrical power is directly related to the amount of current and voltage within a system. Power is measured in Watts

Calculate the Mechanical Efficiency of the winch at different load settings Force Distance Time

Calculate the Mechanical Efficiency of the winch at different load settings Force Distance Time Current Volts 0 24 m 180 s 15 A 12 V 7000 N 24 m 360 s 100 A 12 V 11000 N 24 m 720 s 160 A 12 V

Thermal Energy (heat) Transfer The transfer or movement of thermal energy Most common types

Thermal Energy (heat) Transfer The transfer or movement of thermal energy Most common types of transfer –Convection –Conduction –Radiation 100% efficiency is unattainable ALL processes are irreversible

1 st Law of Thermodynamics Law of energy conservation applied to a thermal system

1 st Law of Thermodynamics Law of energy conservation applied to a thermal system – Thermal energy can change form and location, but it cannot be created or destroyed. – Thermal energy can be increased within a system by adding thermal energy (heat) or by performing work in a system.

2 nd Law of Thermodynamics Entropy is the measure of how evenly distributed heat

2 nd Law of Thermodynamics Entropy is the measure of how evenly distributed heat is within a system. - A system tends to go from order to disorder Order Disorder Firewood has low entropy (molecules in order) when stacked and high entropy when burning (molecules in disorder). The total amount of energy in the world does not change, but the availability of that energy constantly decreases.

Thermal Energy Transfer Equations

Thermal Energy Transfer Equations

Tensile Test Data Calculate the stress in the dog bone with a 430 lb

Tensile Test Data Calculate the stress in the dog bone with a 430 lb applied force.

Tensile Test Data Manipulating Elongation Results To eliminate test results based on sample size,

Tensile Test Data Manipulating Elongation Results To eliminate test results based on sample size, calculate sample strain §Strain (e) - the amount of stretch per unit length § Elongation (d) under load divided by the original Length (L 0)

Tensile Test Data Calculate the strain in the dog bone with an elongation of

Tensile Test Data Calculate the strain in the dog bone with an elongation of 0. 0625 in.

Tensile Test – Stress-Strain Curve

Tensile Test – Stress-Strain Curve

Tensile Test – Stress-Strain Curve Modulus of Elasticity (E) The proportional constant (ratio of

Tensile Test – Stress-Strain Curve Modulus of Elasticity (E) The proportional constant (ratio of stress and strain) A measure of stiffness – The ability of a material to resist stretching when loaded An inherent property of a given material

Centroid Location The centroid of a square or rectangle is located at a distance

Centroid Location The centroid of a square or rectangle is located at a distance of 1/2 its height and 1/2 its base. H B

Centroid Location The centroid of a right triangle is located at a distance of

Centroid Location The centroid of a right triangle is located at a distance of 1/3 its height and 1/3 its base. H B

Moment of Inertia Principles What distinguishes beam A from beam B? Will beam A

Moment of Inertia Principles What distinguishes beam A from beam B? Will beam A or beam B have a greater resistance to bending, resulting in the least amount of deformation, if an identical load is applied to both beams at the same location?

Moment of Inertia Principles Why did beam B have greater deformation than beam A?

Moment of Inertia Principles Why did beam B have greater deformation than beam A? Difference in moment of inertia due to the orientation of the beam Calculating Moment of Inertia – Rectangles h

Modulus of Elasticity Principles Beam Material Length Width Height Area I A Douglas Fir

Modulus of Elasticity Principles Beam Material Length Width Height Area I A Douglas Fir 8 ft 1 ½ in. 5 ½ in. 8 ¼ in. 2 20. 8 in. 4 B ABS plastic 8 ft 1 ½ in. 5 ½ in. 8 ¼ in. 2 20. 8 in. 4

Modulus of Elasticity Principles What distinguishes beam A from beam B? Will beam A

Modulus of Elasticity Principles What distinguishes beam A from beam B? Will beam A or beam B have a greater resistance to bending, resulting in the least amount of deformation, if an identical load is applied to both beams at the same location?

Modulus of Elasticity Principles Why did beam B have greater deformation than beam A?

Modulus of Elasticity Principles Why did beam B have greater deformation than beam A? Difference in material modulus of elasticity – The ability of a material to deform and return to its original shape Characteristics of objects that affect deflection (ΔMAX) Applied force or load Length of span between supports Modulus of elasticity Moment of inertia

Calculating Beam Deflection Beam Material Length (L) Moment Modulus of Force of Inertia Elasticity

Calculating Beam Deflection Beam Material Length (L) Moment Modulus of Force of Inertia Elasticity (F) (I) (E) A Douglas Fir 8. 0 ft 20. 80 in. 4 1, 800, 000 250 lbf psi B ABS Plastic 8. 0 ft 20. 80 in. 4 419, 000 psi 250 lbf

Method of Joints Truss Dimensions B 4. 0 ft RAx A θ 2 θ

Method of Joints Truss Dimensions B 4. 0 ft RAx A θ 2 θ 1 C D 3. 0 ft 7. 0 ft RAy RCy 500 lb