What is Engineering Graphics -...

IE102 Engineering Drawing & GraphicsDr C Erdem IMRAK @ 2004

What is Engineering Graphicsis a visual means to develop ideas

and convey designs in a technical format.

is the dominant means to communication among engineers in industry.

Engineering graphics and the skills associated are developed early in an engineer’s education.


What is Engineering Graphics

Several of the topics that are covered in engineering graphics are listed below:

• Sketching• Geometric Modeling• Engineering Drawing/Documentation• Assembly Drawing• Visualization• Rapid Prototyping


Computers in The Engineering Office

Computers are classified as analog or digital.

Analog computers are generally used for mathematical problem solving. (control electronic, mechanical equipment)

Digital computers count by digits in distinct steps. (electric wall clock)

Polish analogue computer “ELWAT”

http://upload.wikimedia.org/wikipedia/commons/c/c9/ELWAT.jpg


Historical Background of Computing

(1830s) C. Babbage developed the idea of a mechanical digital computer. (undertake laborious calculations ; store the results for further use)

(1904) A. Fleming invented the first diode.(allow current to flow in one direction)

L. De Forest devised the triode valve. (control the flow of current)

Babbage's Difference Engine

http://commons.wikimedia.org/wiki/Charles_Babbage

http://commons.wikimedia.org/w/index.php?title=Difference_Engine&action=edit

http://en.wikipedia.org/wiki/Image:Punch-card-blue.jpg


Historical Background of Computing

(1940s) Thermionic valves was used in the first electronic computers.(filling large rooms; generating large amounts of heat)

(1947) The first transistor was developed at Bell Lab. (valve computer !)

2nd generation computer; the transistor was introduced.

3rd generation computer; based on small-scale integrated circuits.(early 1960s)

4th generation computer; based on integrated circuit.

http://upload.wikimedia.org/wikipedia/commons/4/4e/Eniac.jpg


1. Introduction to Computer Aided Drawing

What is CADD ?Computer-aided drawing is a technique where

engineering drawings are produced with the assistance of a computer and, as with manual drawing, is only the graphical means of representing a design.

Computer-aided design, however, is a technique where the attributes of the computer and those of the designer are blended together into a problem-solving team.



Two-dimensional (2D) computer drawing is the representation of an object in the single-view format which shows two of the three object dimensions or the mutiview format where each view reveals two dimensions.



Three-dimensional (3D) computer drawing is the coordinate format. Three dimensional computer aided drawing allows the production of geometric models of a component or product for spatial and visual analysis.



The advantages of using CADD systems are listed as follow:

constant quality drawing saving on repetition creation of database greater accuracy creation of library multicolour drawings use of layers editing functions



History And Background

1963 Sketchpad in MIT

The first computer aided drawing system was introduced by IBM.



Sketchpad was a revolutionary computer program written by Ivan Sutherland in 1963 in the course of his PhD thesis. It helped change the way people interact with computers.Sketchpad is considered to be the ancestor of modern computer-aided drafting (CAD) programs as well as a major breakthrough in the development of computer graphics in general.

http://en.wikipedia.org/wiki/Ivan_Sutherland




http://en.wikipedia.org/wiki/Computer-aided_drafting






Ivan Sutherland demonstrated with it that computer graphics could be utilized for both artistic and technical purposes in addition to showing a novel method of human-computer interaction.Sketchpad was the first program ever to utilize a complete graphical user interface. Sketchpad used an x-y point plotter display as well as the then recently invented light pen.

http://en.wikipedia.org/wiki/Computer_art

http://en.wikipedia.org/wiki/CAD

http://en.wikipedia.org/wiki/Human-computer_interaction



http://en.wikipedia.org/wiki/Light_pen



The clever way the program organized its geometric data pioneered the use of "objects" and "instances" in computing and pointed forward to object oriented programming. Sketchpad ran on the Lincoln TX-2 computer at MIT.In 1963 most computers ran jobs in batch jobmode only, using punch cards or magnetic tapereels submitted by professional programmers or engineering students.

http://en.wikipedia.org/wiki/Geometry

http://en.wikipedia.org/wiki/Object_oriented_programming

http://en.wikipedia.org/wiki/Lincoln_TX-2

http://en.wikipedia.org/wiki/Massachusetts_Institute_of_Technology

http://en.wikipedia.org/wiki/Batch_job

http://en.wikipedia.org/wiki/Punch_card

http://en.wikipedia.org/wiki/Magnetic_tape

http://en.wikipedia.org/wiki/Engineering



History And Background – 2 In modern systems the light pen

has been replaced by more effective pointing hardware, that is a digitizer tablet, a mouse .



CAD system and Hardware(a) the mainframe computer(b) the minicomputer

(c) the microcomputer

Input DevicesThe input devices are used for making selections from a menu,

which is a layout of a variety of commands and functions required to operate the system. Sending these commands into the computer produces complete engineering drawings.



Mouse Digitizer (tablet)Light pen JoystickScanner



CAD system and Hardware –2

Output DevicesThe output devices receive data from the

computer and provide an output, hard copy.

(a) impact printers (dot matrix)(b) non-impact printers include electrostatic, ink-jet and laser(c) flatbed plotters(d) drum plotters



The User InterfaceCAD systems may be considered as comprising a large number of

functions for creating or manipulating the design model. Traditionally, there are two ways in which this is achieved:

Command-based systemsCommand-based systems operate by reading a command and its

parameters entered by the user, carrying out the required actions, then waiting for the next command.

command (optional parameters , target object)



The User Interface –2

Menu-driven systemsThe menu-driven approach contrasts markedly with the command

approach. The basic principle is that the user is at any time presented with a list or menu of the functions that are available to be selected. The most important of these rules are:

A clear, well presented screen layout.Easy function selection by a well-structured menu system.Meaningful function names.Meaningful and helpful prompts to the user.Easily accessible and clearly written help information.



CADD FUNCTIONALITYThe main benefits of a computerized draughting and design system

over those of manual methods is this ability to represent the design of a component or assembly in a geometrically accurate format so that the same model can be used for other modelling, analysis and manufacturing work.

The functions can be said to fall into three categories: Synthesis type functions are concerned mainly with the creation of

geometric features and drawing detailsModification functions include those which allow for the deletion

and editing of existing geometry or detail.Management functions are concerned with how the drawing is

presented both on the screen and eventually on paper.



CADD SYSTEM SELECTIONThere is a large variety of different CADD packages available on

the market these days and the design manager is faced with the enormous problem of selecting a package to suit the demands of the company and its product range. A lot of ease and efficiency has been obtained with the use of CADD systems.

Among the more widely used CAD systems are AutoCAD, CATIA, SolidWorks, I-DEAS, and ProEngineer. Most of these packages have both a 2D and 3D component or have an integrated 2D and 3D modeling system. The newer versions of drawing software operate under a menu system which can be accessed through keyboard input or mouse manipulation.



CADD SYSTEM SELECTION – 2

According to these factors, the system must have;

Functional abilities: the abilities to perform memory circuits.Memory capacity : evaluation between main and branch memory

circuits.Data transfer characteristics : when we consider data transfer

between two computers, or a main computer and a station, we have to keep in mind the need to decrease computing time



CADD SYSTEM SELECTION – 3 The size of the company and the amount of investment capital

available will be one of the main deciding factors but there aremany other questions to be considered:

Mainframe or PC/workstation platform? Two dimensions or three? Lines, surfaces or solids? Other analysis tools needed? Will the ability to transfer the

geometry to these modelling and analysis systems be needed?Compatibility with other systems needed? How good is the maintenance and support from the suppliers?How much, how good and how long is the training? How easy is it to expand the system?



AutoCADAutoCAD is PC-based CAD software products (late 1982).

System Requirements for AutoCADWindows NT or Windows 95/98/2000Intel 486 or Pentium processor or compatible32 MB of RAM 50 MB of hard disk space64MB of disk swap space2.5 MB of free disk space during installation only CD-ROM drive640 x 480 VGA video display (1024 x 768 recommended)Windows-supported display adapterMouse or other pointing device



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MECHANICAL DESKTOP

Mechanical Desktop offers greater ease of use, flexibility and speed, 2D drawing capabilities for mechanical design, and greatly expanded 3D goemetric coverage. Mechanical Desktop is an integrated package of advanced 3D modeling tools, and 3D drafting and drawing capabilities that help you conceptualize, design, and document your mechanical product.



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Part / Assembly Environment

Assembly ModeScene ModeDrawing Mode



PRO/ENGINEERPro/ENGINEER or Pro/E, is a three-dimensional (3D), feature-

based, solids model-ing system. It was developed by Parametric Technologies Corporation (PTC) in the late 1980s.

Features are three-dimensional (3D) geometries that have direct analogies to shapes that can be machined or manufactured, such as holes or rounds. Feature-based solids modeling creates and modifies geometric shapes that make up an object in a way that readily represents common manufacturing processes.


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SOLID WORKS

SolidWorks is mechanical design automation software that takes advantage of the familiar Microsoft®WindowsTM graphical user interface. This easy-to-learn tool makes it possible for mechanical designers to quickly sketch out ideas, experiment with features and dimensions, and produce models and detailed drawings.


1. Introduction to Computer Aided Drawingmenu bar

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I-DEAS (INTEGRATED DESIGN ENGINEERING ANALYSIS SOFTWARE)

I-DEAS (Integrated Design Engineering Analysis Software) is a computer aided design (CAD), manufacturing (CAM), and engineering (CAE) package. I-DEAS is a complete Mechanical Computer Aided Engineering System for the engineering department. It provides full function design, analysis, drafting, testing, and NC programming in support of mechanical design automation.

This software was designed to facilitate a collaborative concurrent engineering approach to mechanical engineering product design and analysis.



I-DEAS The package is separated into five distinct families, which are

selected from the first menu option entering I-DEAS. I-DEAS Solid Modelling (Geomod) I-DEAS Drafting (Geodraw) I-DEAS Engineering Analysis (Supertab) contains finite element

modelling for finite element solvers such as ANSYS or ABAQUES. I-DEAS System Dynamic (Systan) is used to design complex

mechanical system. I-DEAS Test Data Analysis (TDAS) offers tools for general and

specific data analysis, project management, and data acquisition



I-DEAS

Design ApplicationModeler TaskDraftingSimulationManufacturingTest



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CATIAstands for Computer Aided Three-dimensional Interactive

Application, is the most powerful and widely used CAD (computer aided design) software of its kind in the world. CATIAwas created by Dassault Systems of France and is marketed worldwide by IBM.

CATIA is used by the automotive and aerospace industries for automobile and aircraft product and tooling design.

http://www.dsweb.com/

http://www.catia.ibm.com/catmain.html



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Web Pages for CAD softwares

Autodesk home page www.autodesk.comPro-Engineer CAD Software www.ptc.comI-DEAS CAD software home page www.sdrc.comSolidWorks CAD software home page www.solidworks.comCATIA CAD software home page www.intergraphics.comCADKEY software www.cadkey.com

http://www.autodesk.com/

http://www.ptc.com/

http://www.sdrc.com/

http://www.solidworks.com/

http://www.intergraphics.com/

http://www.cadkey.com/



You will learn parametric design and basicdrawing functions. The steps to follow are:Screen CoordinatesGeometric ParametersGeometry Creation (Line, Circle, Arc etc.)Modification (move, copy etc)Automatic Functions (dimensioning, cross-hatching etc.)Management (zoom, layering etc.)

Prepare a pen & a notebook ....

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