MET 214: Machine Elements

Syllabus

MET 214: Machine Elements: Syllabus Fall 09

Text: Machine Elements in Mechanical Design-4Th Ed. By Robert L. Mott

Instructor: Craig D. Engle

Office: ANDR 222

Office Hours: MWF: 10:00am-2:00pm & 6:30pm-7:50 pm

                            T,Th:  10:30am-1:50pm

                            Sat: 11:00am-2:00pm & 7:00pm-9:30pm and by appointment (email to confirm sat hrs)

Telephone : Home 219-924-2858       Email: englec@calumet.purdue.edu

Course Description:

The Theories and methods developed in statics, dynamics, and strength of materials are applied to the selection of basic machine components. The course will develop the fundamental principles required for the selection of the individual elements of which a machine is composed. Selected course topics are included as computer programming projects.

Class 3, Credit3. Prerequisites: MET 161 (Computer applications), MET 211 (Strength of Materials), and MET 213 (Engineering Mechanics: Dynamics); or consent of instructor.

 

Students Learning Objectives:

Upon successful completion of this course, students should be able to:

1)      Recognize examples of mechanical systems in which the application of the principles discussed in this course is necessary to complete their design

2)      Present design calculations in a professional, neat, and orderly manner that can be understood and evaluated by others knowledgeable in the field of machine design

3)      Specify suitable types and sizes of belts and sheaves (chains and sprockets) to transmit a given level of power at specified speeds for the input and output sheaves (sprockets)

4)      Recognize and describe the main features of different gears

5)      Define train value as it pertains to the overall speed ratio between the input and output shafts of a gear box

6)      Compute the forces exerted on gear teeth as they rotate and transmit power

7)      Use appropriate stress analyses to determine relationships among applied forces, the geometry of gear teeth, and other specified factors , in order to make decisions about those variables

8)      Compute the forces exerted on shafts by gears, belt sheaves, and chain sprockets

9)      Specify the time required to accelerate a system or to bring it to a stop with the application of a given torque using brakes / clutches

10)   Integrate the mechanical concepts necessary to complete a preliminary design of a conveyor system

                                               

                                                                                                                                                                                                                                                                                       Course Policies

All students are expected to attend all classes. Homework is intended to supplement the lecture with application experience and will be collected, graded and returned to the student. Due dates for Homework will be identified when homework is assigned. Homework includes problems to be worked in class and due in same class period. No late homework will be accepted after solutions are made available to class unless an exception is made by the professor that could involve a different problem set. Solutions to homework are generally made available either when homework is collected or one week after homework is collected, depending upon circumstances. Any and/or all exceptions concerning late homework are at the sole discretion of the instructor without any regard for other considerations including, but not limited to, exceptions previously granted. Any late homework that is accepted will be reduced by 15%. If you miss a class, it is YOUR responsibility to obtain the class notes & homework assignment from a colleague. If I cannot read or follow your work, I will assume it is wrong.

Homework problems may be assigned from time to time during class, worked and collected for grading during the same period to reinforce concepts and/or promote attendance. Quizzes will be given from time to time to insure key points are being communicated.

Overall grade is based on, homework, quizzes, reports, examinations and class participation. Weight is based on the following schedule.

 

                                            2 semester exams (20% ea)                    40%

                                            1 Final exam                                                   25%

                                            Homework/quizzes                                     25%

                                            Class participation                                         10%

 

Grades are assigned on a curve that follows to a loose degree a conventional grading scale. Exact scores for cutoffs between letter grades will be at the sole discretion of the instructor, with the range typically, but not required to be, as follows:

                              90-100               A

                              80-89                 B

                              70-79                 C

                              60-69                 D

                              < 60                    F

Adjustments to the above letter grade scale can be made at the sole discretion of the instructor. Considerations at the sole discretion of the instructor could include how the final point totals are distributed.  Make up tests are permitted only in rare cases (excused absences such as a death in the family, verifiable illness, or other emergencies approved by the instructor at the sole discretion of the instructor). Contact your professor by phone or email prior to missing a test whenever possible. Students are strongly advised not to expect that a makeup test is always an alternative to scheduled tests. Make up tests must be taken in the instructor’s office at the convenience of the instructor. A grade of zero will be recorded for each test missed due to an unexcused absence. Class participation points may be adjusted to prevent anyone receiving a grade of “C” on the final exam from obtaining an “A” in the class.

Americans with Disabilities Act:

All qualified students enrolled in this course are entitled to reasonable accommodations It is the students responsibility to inform the instructor of any special needs during the first week of the classes.

 

Academic Integrity Statement:

Ethics are an integral part of being a student and a professional. Academic integrity is the hallmark of this university. Therefore, Purdue University calumet does not tolerate academic dishonesty in any form. If a student breaches integrity, the student risks sanctions in both the academic and conduct arenas. Academic dishonesty includes, but is not limited to, the unauthorized use of other’s intellectual property (plagiarism) and lying to an instructor or other university employee. Such actions will result in a failing grade in the assignment with strong possibility of course failure, and the strong possibility of referral to the Office of the Dean of Students or a conduct sanction. (See Purdue University’s student handbook).

 

EMERGENCY PROCEDURE GUIDES       -           In the event of…

 

Fire…

  • Know the location of the fire alarms, fire extinguishers and evacuation routes and exits.
  • Evacuate when the alarm sounds.
  • Help ensure everyone evacuates.
  • Assist others during the evacuation.
  • Call University Police (2911 if you are using a campus phone or 899.2911) if you or others need assistance or if someone is trapped in an elevator.

Severe Weather…

  • Know the location of your Storm Safe Area.
  • Listen for announcements via the campus public address system.
  • Follow instructions.
  • Help ensure everyone is aware and follows instructions.

Medical Emergency…

  • Immediately call University Police (989.2911)
  • Immediately call 9-911 (if you are using a campus phone or 911 if you are using a cell phone) if an ambulance is needed.

Power Failure…

  • If it lasts more than a few seconds…secure your space and go to the first floor.
  • Listen for announcements via the campus public address system.
  • Follow instructions.
  • Help ensure everyone follows instructions.
  • REMEMBER…emergency lighting is limited in duration…it is intended to help you evacuate safely…it is not intended to help you keep working.

Elevator Failure…

  • If you are trapped, activate the elevator alarm and use the emergency telephone to contact University Police.
  • If you hear someone who is trapped in an elevator, reassure them that you will call University Police (989.2911).

Criminal Activity…

  • Call University Police (989.2911) immediately if you observe a crime, note a suspicious person or have knowledge of a crime previously committed. The confidential hotline number for reporting suspicion of criminal behavior is 989-2912.

Dangerous Individuals…

  • Call University Police (989.2911) immediately if you observe someone demonstrating apparently irrational or harmful behavior.
  • Also please take note of the campus resources that are available should you believe that a student may benefit from intervention that could prevent a potential emergency situation:

                Dean of Students office:  989-4141

                Counseling Center:  989-2366

Hazardous Condition…

  • If you see, smell, touch or hear something that is a hazard or has the potential to become a hazard call University Police (989.2911).

Sounds like gunshot…

  • Turn off lights to the room.
  • Lock or barricade the door.
  • Hide where you can’t be seen.
  • Call the University Police (989.2911)
  • Wait for Police to arrive.

 

WHEN IN DOUBT…CALL UNIVERSITY POLICE AT 989.2911

 

 

Course Schedule

Week #1: Lecture #1:

Chapter 1 The Nature of Mechanical Design

                1)Discuss market segments (fields) where mechanical products are designed and produced.

                                a) illustrate how over all dynamical system performance requirements translate to

                                 requirements for sub system mechanical components to develop sensitivity of how

                                control theory interacts with the design of machine elements.

               

                2) Discuss design process and use material handling system configurations as examples for the

                  design process.

                                a) identify how supply chain management strategies evolve to system requirements

                                 involving:

1)      Product dimensions

2)      Product weight

3)      Travel time

4)      Travel distance

5)      Velocity and acceleration profiles

b) introduce candidate systems and identify key components

                1) conveyor systems

                2) linear slides/ball screws

c) discuss how mass inertias of system configurations can be reflected to drive shaft of

   motor to assist in translating dynamical system specifications to requirements for sub 

                                system machine elements.

   

                3) Begin review of strength of material presented in chapter 3 of book by Mott.

                                a) introduce relationship between center of gravity and centroid.

                                b) introduce moment of inertia and mass moment of inertia

                                c) radius of gyrations

 

                4) Demonstrate how to calculate mass moment of inertia for useful shapes encountered in

                   machine elements including cylinders.

   

                5) Introduce Newton’s equation of motion for linear and rotational systems and identify how

                 dynamical considerations including mass moments will influence requirement for machine

                elements  through force and/or torque considerations. Introduce conventional HP relationships

                used to establish torque and/force requirements for machine elements. Work examples and

                find X(t) and Θ (t) for given force and/or torque profiles for example components.

 

 

Week #1: Lecture #2

 

1)      Review normal stresses, strains and modulus of elasticity.

2)      Review material properties from chapter 2 of book

3)      Review techniques for creating normal stress diagrams.

4)      Review Shear stress and strain and modulus of elasticity.

5)      Review material properties from chapter 2

6)      Review shear stress on mutually perpendicular planes and diagonal of elemental cube

7)      Review Poisson’s ratio and coefficient of thermal expansion.

8)      Review Shear stress applications associated with keys, pins and couplings from chapter 11 excluding splines.

9)      Review stress concentration factors

 

Week #2: Lecture #3

1)      Review equations for torsion: shear stress and angle of twist

2)      Develop techniques for drawing internal torque verses position diagrams.

3)      Work examples involving gears and/or sprockets and/or pulleys mounted on shafts.

4)      Introduce dynamic considerations including dynamic twisting and resonance.

 

Week #2: Lecture #4

1)      Review classification of supports/beams

2)      Review statically determinate verses statically indeterminate

3)      Assess implications of statically determinate assumption on bearing types

4)      Introduce categories of bearings

5)      Review shear and moment diagrams/work examples in 2 planes.

6)      Review tensile and compressive stresses in beams due to bending

 

Week #3: Lecture #5

1)      Review deflection of beams

2)      Leaf Springs

 

Week #3: Lecture #6

1)      introduce combined stresses

A)     non axial loads

1)      stress due to equivalent axial load

2)      stress due to bending moment

3)      combined distribution

B)      Loads not parallel to axis

C)      Superposition of shearing stresses: max/min values

2)      Work examples that serve as introduction to force systems associated with gear systems of various types including spur gears and/or helical gears. 

 

Week #4: Lecture #7

1)      Review of Mohr’s circle (time allowing)

2)      Applications to failure analysis of twisted shaft, ductile verse brittle material

 

Week #4: Lecture #8:

Flexible Power Transmission elements, belt drives and chain drives

1)      Develop equations relating to rotary motion, linear belt speed, power and torque to belt tension.

2)      Overview belt options and standard V-belt cross sections

3)      Review procedure for V belt selection

 

Week #5:  Lecture #9

1)      Review procedure for belt selection

2)      Work examples for belt drives including torque diagrams, shear and moment diagrams in two planes.

 

Week #5: Lecture #10

3)      Work examples for belt drives

4)      Review chain drive terminology and geometry, classification of chains

5)      Highlight roller chains and roller chain standards.

6)      Develop equations associated with center distance, chain length, chain speed.

7)      Mention chordal action.

 

Week #6 Lecture #11

1)      Review design procedures for chain selection, lubrication.

2)      Analyze conveyor system assuming chain drive and reflect impedances to drive shaft of motor. Develop relationships involving motor torque and conveyor motion.

3)      Work examples for chain drive interfaces with shear and moment diagrams in two planes. Determine shaft diameter needed to meet system requirements. Drawing torque diagram for drive components. Identify maximum bending moments.

 

Week #6 Lecture #12

1)      Work example problems involving flexible power systems (may want to analyze linear slide system/Ball screw combination being driven by a chain drive)

 

Week #7 Lecture #13

1)      Review for test #1

2)      Cams; describe types of cams and methods of developing cam profiles

3)      Identify pressure angle.

 

Week #7 Lecture #14

1)      Test #1

 

Week #8 Lecture #15

1)      Work cam shaft example and identify bearing reaction

2)      Spurs gears: develop equations for friction wheels

3)      Introduce notion of slippage and gear teeth and define gear teeth to extent necessary to analyze speed ratios in terms of diameter of pitch circle, number of teeth.

4)      Introduce notion of Train value and work  gear train examples

5)      Introduce notion of reflected impedances for gear trains and how reflected impedance can be used to relate system performance requirements to machine element specifications. 

 

Week #8 Lecture #16

1)      Introduce fundamental law of gearing

2)      Introduce definition of involute

3)      Develop geometry associated with mating gears

a.       Pitch circles

b.      Line of centers

c.       Base circles

d.      Line of action/ pressure angle

e.      Center to center separation

f.        Circular pitch to diametrical pitch

g.       Line velocity of pitch point

 

Week #9 Lecture #17

1)      Review gear teeth features

2)      Analyze force system in spur gear

a.       Resolve force acting along line of action into tangential and radial components

b.      Develop relationships between pitch line speed, power, force components and torque. 

 

Week #9 Lecture #18

1)      Work spur gear examples involving shear and moment diagrams in two planes.

a.       Determine bearing reactions

b.      Draw resisting torque diagrams

c.       Work examples of spur gear applications and possibly shaft design

 

Week #10 Lecture #19

1)      Stress in gear teeth

a.       Introduce Lewis equation and compensating factors

b.      Develop procedure for material selection

 

Week #10 Lecture #20

1)      Review procedure for gear design

2)      Work examples – use mechatronics laboratory

3)      Use Excel program for design of spur gears

 

Week #11 Lecture #21

1)      Review Test #2

2)      Helical gears

a.       Analysis of geometry of force system

b.      Definition of helix

c.       HP relationships associated with force system components

d.      Method of determining direction of axial thrust/Herringbone

e.      Advantage/Disadvantage verses spur gears

 

Week #11 Lecture #22

1)      Test #2

 

Week #12 Lecture #23

1)      Shaft stress system associated with helical gears

2)      Gear teeth stress for helical gears

3)      Work examples

a.       Bearing reactions

b.      Moment of inertia calculations

 

 

Week #12 Lecture # 24

1)      Bevel gears

a.       Friction wheel analysis

b.      Bevel gear geometry

c.       Analysis of force system on bevel gears

d.      Strength and durability of bevel gears

 

Week #13 Lecture #25

                1) Bevel gear design example

 

Week #13 Lecture # 26

1)      Worm Gears

a.       Forces, Friction, and efficiency in Worm Gear sets

b.      Stress in Worm Gear teeth

c.       Surface Durability of Worm Gear Drives

 

Week #14 Lecture # 27

1)      Shaft Design

a.       Shaft design procedure

b.      Forces on shafts from different machine elements

c.       Stress concentration in shafts

d.      Design stresses on shafts

e.      Shaft design examples

f.        Using Excel for shaft design

 

Week #14 Lecture # 28

1)      Motion Control – Clutches and Brakes

a.       Description of clutches and brakes

b.      Types of Friction Clutches and Brakes

c.       Performance Parameters

 

Week #15 Lecture # 29 and 30

1)      Motion Control – Clutches and Brakes (continued)

a.       Time required to accelerate a load

b.      Inertia of the system referred to the clutch shaft speed

c.       Effective inertia for bodies moving linearly

d.      Energy absorption: Heat dissipation requirements

e.      Other type of clutches and brakes