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Traian CICONE 1/31ME&M-I- Introduction
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
Traian CICONE 2/31ME&M-I- Introduction
• 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
Course Outcomes
Traian CICONE 3/31ME&M-I- Introduction
Course DescriptionMachine Elements & Mechanisms – 5 Credits
3 hours Lecture1 hour Laboratory1 hour Tutorial
Machine Design – 2 hours Project – 2 Credits
PART 1
• Introduction in Mechanical Engineering DesignThreaded Fasteners & Power ScrewsHub-on-shaft Assemblies (Dismountable)Permanent Assemblies/Joints (Welds, Bonds)SpringsShaftsIntroduction in Tribology (Friction-Wear-Lubrication)
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Traian CICONE 4/31ME&M-I- Introduction
References
Course WEB Pagehttp://www.omtr.pub.ro/Colectivul_catedrei/PaginiPersonale/t_cicone/me&m/me&m.htm
Traian CICONE 5/31ME&M-I- Introduction
Engineering Design
Design - All activities preceding the transformation into realityby execution, with correlated material, and financial resources of an idea or a given subject.
Engineering - Applied science concerned with the understanding of scientific principles and applying them to achieve an imposed goal
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.
Traian CICONE 6/31ME&M-I- Introduction
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)
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Traian CICONE 7/31ME&M-I- Introduction
Working Machines (Technological Machines)
Excavator
Wheel loader
Perform useful work: machine-tools .
Corded drill
Traian CICONE 8/31ME&M-I- Introduction
Transport Machines
Turbo-pump(Ariane)
Transfer/Transport of materials: pumps, compressors, fans
Centrifugal-pump
Traian CICONE 9/31ME&M-I- Introduction
Power Machines (Engines)Transfer/Transport of energy: turbines, internal combustion engines, etc.
Turbine in Nuclear Power Plant (EDF )
4
Traian CICONE 10/31ME&M-I- Introduction
Internal Combustion Engine
Power Machines (Engines)
Traian CICONE 11/31ME&M-I- Introduction
Apparatus/Instruments
Pressure indicatorManometer
Micrometer
Transfer/Transport of information: typewriter, pressure indicator, etc.
Traian CICONE 12/31ME&M-I- Introduction
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
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Traian CICONE 13/31ME&M-I- Introduction
Scissors screw jack
Linkage MechanismsSlider-crank mechanism
Screw mechanism
Traian CICONE 14/31ME&M-I- Introduction
Linkage Mechanisms
windshield wiper mechanism
Traian CICONE 15/31ME&M-I- Introduction
Gear Mechanisms
6
Traian CICONE 16/31ME&M-I- Introduction
Cam Mechanisms
Camshaft with Plate Cam imparting on a Flat Follower, a Push Rod, a Rocker arm and the Valve.
Pumping mechanism
Traian CICONE 17/31ME&M-I- Introduction
Complex MechanismsLinkage + Gear + Cam.
Traian CICONE 18/31ME&M-I- Introduction
MACHINE
MECHANISM
Machine Element
Internal combustion engine
Slider-crankmechanism Crankcase Distribution
mechanism Etc.
Bolt Crankshaft Connecting rodPiston ….
The structure of a machine
7
Traian CICONE 19/31ME&M-I- Introduction
Machine element/component/part
Classification
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.
Complexity• Simple (screws, nuts, shafts, wheels, gears, etc.)
• Compound (bearings, disk friction clutches, V-belt transmissions, etc.)
• Complex (planetary gear boxes, etc)
Destination• General purpose
• Special purpose
Traian CICONE 20/31ME&M-I- Introduction
– sometimes is the creation of an original product– typically is the refinement or modification of an existing product
Engineering Activities
Design 25%Development 10%Research 10%Management 8%Sales 10%Technical Service 12%Construction 10%Manufacturing 15%
Engineering Design
“Design is the most creative part of the total engineering process.”
Traian CICONE 21/31ME&M-I- Introduction
Products’ life-cycle costs
Productdevelopment
Manufacturing Design
Construction (Manufacturing)
Materials Promotion, Distribution, Advertising
Real cost
Influence on the final value by
specific decisionsLife-cycle cost
70%
18%
10%
7%5%
Cost of a new product 100%
0%
50%
5%
40%
25%
20%
over 70% of a products’ life-cycle costs are committed at the design time, particularly the conceptual design phase
8
Traian CICONE 22/31ME&M-I- Introduction
Mechanical (Machine) Design
The process of selecting mechanical components and putting them together to accomplish a
desired function.Integration requires• Imagination• Component familiarity
Traian CICONE 23/31ME&M-I- Introduction
Engineering Design
Identify a Need
Preliminary Design
Conceptual Design
Final Design
Manufacture
Sales & Delivery
Design of Machine Elements
Background research
Goal statement
Task specifications
Synthesis
Analysis
Selection
Detailed design
Prototyping & testing
Documentation
Traian CICONE 24/31ME&M-I- Introduction
• 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.
The Design Process
Computer applications for analysis of a design are essential.
9
Traian CICONE 25/31ME&M-I- Introduction
• 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
Design Steps
Traian CICONE 26/31ME&M-I- Introduction
Define the problem
State the givens
Make appropriate assumptions
Preliminary design decisions
Design sketches
Mathematical models
Analysis of the design
Evaluation
Document results
Definition stage
Preliminary design stage
Detailed design stage
Documentation stage
A suggested procedure for the designer
Traian CICONE 27/31ME&M-I- Introduction
Traditional Design Process
Design is ITERATIVE
10
Traian CICONE 28/31ME&M-I- Introduction
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
Design Considerations
Engineering Ethics - Ex. ASME Principles & Canons
Traian CICONE 29/31ME&M-I- Introduction
Standards and codes represent a prescriptive approach to design that may be incorporated into a design process.
StandardsA set of technical definitions and guidelines for designers and manufacturers.
Written by “experts”, they are considered voluntary.
ASME – AGMA – AISI - ANSIISO - BS, DIN, NF, ISO-SRISO or ASME groups develops and maintains standards using committees.
CodeA 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.
Standard & Codes
Traian CICONE 30/31ME&M-I- Introduction
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
Economics
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Traian CICONE 31/31ME&M-I- Introduction
Design Characteristics
Detail & Assembly DrawingsDesign Results
Design Methods CAD – Computer Aided Design CAE – Computer Aided Engineering
Team WorkingGood communication skills
(both oral and written)
Writing, sketching, using CAD tools, etc.Giving presentations