Machine Elements & Mechanisms. Course Outcomes. Course Description. An applications course Uses a wide range of your background courses:

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1 Machine Elements & Mechanisms An applications course Uses a wide range of your background courses: Statics & Dynamics Strength of Materials Materials and Processes Manufacturing Processes Fluid Mechanics Technical Drawing Introduction to Design Elasticity & Plasticity Heat Transfer Mechanical Vibrations 1/31 Course Outcomes Ability to apply knowledge of mathematics, science, and engineering in the field of mechanical engineering Ability to design a system, component, or process to meet desired needs in the field of mechanical engineering Ability to identify, formulate and solve mechanical engineering problems Understanding of professional and ethical responsibility in the field of mechanical engineering Ability to communicate effectively Ability to use the techniques, skills, and modern tools necessary for the practice of mechanical engineering 2/31 Course Description Machine Elements & Mechanisms 5 Credits 3 hours Lecture 1 hour Laboratory 1 hour Tutorial Machine Design 2 hours Project 2 Credits PART 1 Introduction in Mechanical Engineering Design Threaded Fasteners & Power Screws Hub-on-shaft Assemblies (Dismountable) Permanent Assemblies/Joints (Welds, Bonds) Springs Shafts Introduction in Tribology (Friction-Wear-Lubrication) 3/31

2 References Course WEB Page 4/31 Engineering Design Engineering - Design - Applied science concerned with the understanding of scientific principles and applying them to achieve an imposed goal All activities preceding the transformation into reality by execution, with correlated material, and financial resources of an idea or a given subject. Mechanical Engineering Design (Machine Design) - A major component of Engineering that deals with the conception, design, development, refinement and application of machines and mechanical apparatus of all kinds. The process of selecting mechanical components and putting them together to accomplish a desired function. 5/31 Definitions: MACHINE Machine An assemblage of parts that transmit forces, motion, or energy in a predetermined manner. Working machines - FORCES Transport machines MATERIALS Power machines ENERGY Apparatus/Instruments INFORMATION (Motion) 6/31

3 Working Machines (Technological Machines) Perform useful work: machine-tools. Excavator Corded drill Wheel loader 7/31 Transport Machines Transfer/Transport of materials: pumps, compressors, fans Centrifugal-pump Turbo-pump (Ariane) 8/31 Power Machines (Engines) Transfer/Transport of energy: turbines, internal combustion engines, etc. Turbine in Nuclear Power Plant (EDF ) 9/31

4 Power Machines (Engines) Internal Combustion Engine 10/31 Apparatus/Instruments Transfer/Transport of information: typewriter, pressure indicator, etc. Pressure indicator Manometer Micrometer 11/31 Definitions: MECHANISM Mechanism Part of a machine that provides the transmission and transformation of a definite mechanical motion. System of rigid bodies that provides the transformation of mechanical motion, and forces of a part into a definite motion and forces of another part. Physical arrangement that provides for the definite motion of the parts of a machine. Linkages Cams Gears Screws 12/31

5 Linkage Mechanisms Slider-crank mechanism Scissors screw jack Screw mechanism 13/31 Linkage Mechanisms windshield wiper mechanism 14/31 Gear Mechanisms 15/31

6 Cam Mechanisms Camshaft with Plate Cam imparting on a Flat Follower, a Push Rod, a Rocker arm and the Valve. Pumping mechanism 16/31 Complex Mechanisms Linkage + Gear + Cam. 17/31 The structure of a machine MACHINE Internal combustion engine MECHANISM Slider-crank mechanism Crankcase Distribution mechanism Etc. Machine Element Piston Bolt Crankshaft Connecting rod. 18/31

7 Machine element/component/part Part of a machine or mechanism with a definite functionality, which can be designed independently, and provides the transmission and transformation of a definite mechanical motion. Classification Destination General purpose Special purpose Complexity Simple(screws, nuts, shafts, wheels, gears, etc.) Compound (bearings, disk friction clutches, V-belt transmissions, etc.) Complex(planetary gear boxes, etc) 19/31 Engineering Design sometimes is the creation of an original product typically is the refinement or modification of an existing product Design is the most creative part of the total engineering process. Engineering Activities Design 25% Development 10% Research 10% Management 8% Sales 10% Technical Service 12% Construction 10% Manufacturing 15% 20/31 Products life-cycle costs 100% Influence on the final value by specific decisions Life-cycle cost 50% Cost of a new product 70% 18% 7% 5% 40% 20% Real cost 25% 0% 10% 5% Product Manufacturing Construction development Design (Manufacturing) Materials Promotion, Distribution, Advertising over 70% of a products life-cycle costs are committed at the design time, particularly the conceptual design phase 21/31

8 Mechanical (Machine) Design The process of selecting mechanical components and putting them together to accomplish a desired function. Integration requires Imagination Component familiarity 22/31 Engineering Design Background research Identify a Need Conceptual Design Preliminary Design Final Design Manufacture Design of Machine Elements Goal statement Task specifications Synthesis Analysis Selection Detailed design Prototyping & testing Sales & Delivery Documentation 23/31 The Design Process Starts with recognition of the need for the product. Both design and redesign require knowledge of the intended use of the product, plus information on the Market Technical data Materials and production For any product design you are part of a team!!! Teamwork is paramount in the modern workplace. Computer applications for analysis of a design are essential. 24/31

9 Design Steps Determine the need Starts with recognition of a need Sketching of the solution (product) is very useful during this step. Establish Known Information Includes gathering information on aspects of the products such as possible materials, market analysis, ability to manufacture, cost to manufacture, etc. Stimulate Design Concepts Consider the various aspects in the manufacture of the product such as material, shape, etc. Investigate Design Concepts with Analytical Tools Use modern methods and tools to analyze design alternatives. Gather all information and review Gather together all information and design alternatives and review so that decisions can be made. Test the design that appears best. Accept, Modify, or Reject Optimize the design by iteration 25/31 A suggested procedure for the designer Define the problem Definition stage State the givens Make appropriate assumptions Preliminary design stage Preliminary design decisions Design sketches Mathematical models Detailed design stage Analysis of the design Evaluation Documentation stage Document results 26/31 Traditional Design Process Design is ITERATIVE 27/31

10 Design Considerations The design of a component or system may be influenced by a number of requirements. If a requirement affects design, it is called a design consideration. For example, if the ability to carry large loads without failure is important, we say that strength is a design consideration. Most product development projects involve a number of design considerations: - Strength/stress - Cost - Thermal properties - Distortion/stiffness - Processing requirements - Surface finish - Wear - Weight - Lubrication - Corrosion - Life - Marketability - Safety - Noise - Maintenance - Reliability - Aesthetic considerations - Volume - Friction - Shape - Recyclability - Usability/utility - Environmental protection -Size Engineering Ethics - Ex. ASME Principles & Canons 28/31 Standard & Codes Standards and codes represent a prescriptive approach to design that may be incorporated into a design process. Standards A set of technical definitions and guidelines for designers and manufacturers. Written by experts, they are considered voluntary. ASME AGMA AISI - ANSI ISO - BS, DIN, NF, ISO-SR ISO or ASME groups develops and maintains standards using committees. Code A set of standards that has been adopted by one or more governmental bodies or incorporated into a contract. Essentially, it has the force of law behind it. 29/31 Economics Strength, safety, reliability, and cost are perhaps the most important design considerations. In general the design alternative that satisfies other design considerations at the lowest costs is to be preferred. Issues affecting the cost of a design include: Product development costs Material choice Manufacturing processes involved Economies of scale Tolerances specified Use of standard sizes and components 30/31

11 Design Characteristics Design Results Detail & Assembly Drawings Design Methods CAD Computer Aided Design CAE Computer Aided Engineering Team Working Good communication skills (both oral and written) Writing, sketching, using CAD tools, etc. Giving presentations 31/31