ME317

1. ME317 Kinematics Dr. James Aflaki

2. Definition of Mechanism • A device that transforms motion to some desirable pattern • A system of elements arranged to transmit motion in a predetermined fashion

3. Definition of Machine • A system of elements arranged to transmit motion and energy in a predetermined fashion

4. Kinematics (History) • Andre Marie Ampere (1775-1836) first used the word Cinematique, French, from the Greek word for motion, describes the study of motion without regard to forces. • Later Cinematiqueanglecized to kinematics and germanized to kinematik.

5. Kinematics (History) • Robert Willis (1800-1875), Prof. of natural philosophy at the University of Cambridge, England, summarized the task of mechanical synthesis. • Five different ways to obtain relative motions between input and output links: • Rolling contact • Sliding contact • Linkages • Wrapping connectors (belts, chains) • Tackle (rope or chain hoists

6. Kinematics (History) • Reuleaux(1829-1905), published TheoretiticheKinematik in 1875, translated into English by Alexander Kennedy (1847-1928) • This text became the foundation of modern kinematics. • Reuleaux defined six basic mechanical components. • The link • The wheel • The cam • The screw • The ratchet • The belt

7. Kinematics (Application) • Any moving machine or device contains one or more kinematic elements such as links, cams, gears, belts, chains. • Familiar examples: • Bicycle • Motorcycle • Cars • Suspension system • Transmission • Break system • Steering wheel system • Construction equipment • Tractors • Bulldozers • Cranes • Backhoes • Robots in assembly lines

8. The Design Process • Engineering design: • The process of applying the various techniques and scientific principles for the purpose of defining a device, a process or a system in sufficient detail to permit its realization • Design may be: • Simple or complex • Mathematical or nonmathematical • Easy or difficult • Trivial problem or of great importance

9. Synthesis • The first step in any engineering design task is synthesis, putting things together. • Define the problem • Make sure that the proposed solution will solve the desired problem.

10. Structured & Unstructured Problems • Structured (Textbook problems): • Given A,B, find D. • Unstructured • Real world design problems (identifying the need) • Design a toy to create bubbles • Design a Lawn Mower • The problem is ill defined. • Unstructured problem leads to blank paper syndrome

11. Background Research • Gather background information on the relevant various aspects of the problem. • This could determine whether this problem or similar type has been solved before. • This will provide a great deal of information on how to solve the problem.

12. Background Research (continued) • There may already be a patent on the problem design. • By the patent’s existing solution • Design something that does not conflict with the patent • Drop the project

13. Goal Statement • Goal statement should be: • Concise • General • Uncolored by any terms that predict a solution • i.e if original statement is Design a Lawn Mower, goal statement may say Design a Means to Shorten Grass not Design a Better Lawn Mower

14. Performance Specifications • Define what the system must do. • Device to should have self-contained power supply • Device to be corrosion resistant • Device to cost less than $100.00 • Device to emit less than 80 db sound intensity at 10 m • Device to shorten 1/10 acre of grass per hour

15. Ideation & Invention • Most individuals underutilize their potential creative abilities. • The creative process: • Idea generation • Frustration • Incubation • Eureka

16. Ideation & Invention • The creative process: • Frustration • When this step is reached: • Leave the problem and do something else • While doing something else, you will be working on the problem subconsciously. • This is called incubation. • An idea will pop up into your consciousness and would seem to be the right solution to the problem, Eureka! • Later analysis may discover some flaws, iterate, more ideation or more research, or even redefining the problem.

17. Analysis • Analysis mans to decompose, to take a part to resolve into its constituent parts • It requires a thorough understanding of both mathematical techniques and the fundamental physics of a given problem • Analysis is used to provide structure to an unstructured problem.

18. Decision Matrix • Used to identify the best solution by using various factors in analysis phase.

19. Detailed Design • Create a complete set of assembly and detail drawings. • Specify all the dimensions and material specifications • Construct a prototype test model • Test the model

20. Production • If possible, manufacture a single model to discover any flaws in your design. • This will prevent embarrassment (to some degrees) and heavy cost. • Use the greatest care in earlier steps of the design process to avoid this.

21. Human Factors Engineering • An applied science that coordinates the design of devices, systems and physical working conditions with the capabilities and requirement of the worker. • Make the machine fit the man. • This is also called, ergonomics

22. Units • System International (SI) • U.S. foot-pound-second (fps) • U.S. inch-pound-second (ips) • All systems are generated from the three quantities in the general expression of Newton’s second law.

23. Units F is force m is mass l is length t is time Choose the units for any three of these quantities, derive the fourth unit

24. Units of Mass • System International (SI)kg kg=Newton seconds squared per meter (N-sec2/m) • U.S. foot-pound-second (fps)slug slugs=Pounds seconds squared per foot (lb-sec2/ft) • U.S. inch-pound-second (ips) blobs blobs=Pounds seconds squared per inch (lb-sec2/in) slug=12 blobs

25. Units of Mass lbm=32.2 slugs lbm=386.4 blobs

26. System of Units in This Book The primary system of units in this book: U.S. ips system

27. Units