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Lecture 01

Introduction

By:

Dr. Mahmoud Elsamanty

Computer Aided Desig

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Outline

Introduction

Geometric Modeling

Coordinate System

Windowing

View Orientation

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IntroductionCourse Content:

CAD/CAM Concepts

Basic of Geometric Modeling

Wireframe Modeling

Surface Modeling

Solid Modeling

Concept of Modelers

Functional Modelers

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Geometric ModelingProduct development activity starts with the design of the product

The challenges before the product designers today are listed below

• Need to have innovation and originality in design

• Need for global collaboration across and beyond the enterprise a

customers and vendors to reduce development lead times

• Need to evaluate feasibility throughout the design process

• Ability to react quickly to design changes as and when change re

• Ability to express the design intent in terms of shape and functio

available

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Requirements of Geometric Mod

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Functions of Geometric Model

•Design analysis:

– Evaluation of areas and volumes.

– Evaluation of mass and inertia properties.

– Interference checking in assemblies.

– Analysis of tolerance build-up in assemblies.

– Analysis of kinematics — mechanics, robotic

– Automatic mesh generation for finite elemen

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• Drafting

– Automatic planar cross sectioning.

– Automatic hidden line and surface removal.

– Automatic production of shaded images.

– Automatic dimensioning.

– Automatic creation of exploded views for technical i

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• Production Engineering

– Bill of materials. – Material requirement.

– Manufacturing resource requirement.

– Scheduling.

•Inspection and Quality Control:

- Program generation for inspection machines.

–

Comparison of produced part with design.

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Geometric Modeling

Geometric modeling is done in three principal ways.

They are:

i. Wire frame modeling

ii. Surface modeling

iii. Solid modeling

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Geometric ModelingGeometric modeling is done in three principal ways.

They are:

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Geometric Modeling

In wire frame modeling the object isrepresented by its edges. In the initial stages

of CAD, wire frame models were in 2-D

Subsequently wire frame 3-D modeling

software was introduced.The wire frame

model of a box is shown in Fig. The objectappears as if it is made out of

thin wires.

WIRE FRAME MODELING

t i d l t d i i

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geometric model represented in wir

model

geometric model represented in ir

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geometric model represented in wir

modelImpossible objects that can be

modelled using a wire-frame model

G i M d li

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Geometric ModelingSURFACE MODELING

In this approach, a component is represented by

its surfaces which in turn are represented by their vertices and edges. For example, eight surfaces

are put together to create a box, as shown in Fig.

Surface modeling has been very popular in

aerospace product design and automotive design.

Surface modeling has been particularly useful inthe development of manufacturing codes for

automobile panels and the complex doubly

curved shapes of aerospace structures and dies

and moulds.

geometric model represented in Su

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geometric model represented in Su

frame model

G t i M d li

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Geometric Modeling

The representation of solid models uses

the fundamental idea that a physical

object divides the 3-D Euclidean space

into two regions, one exterior and one

interior, separated by the boundary of the

solid.

SOLID MODELING

G t i C t ti M th

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Geometric Construction Meth

The three-dimensional geometric constructi

methods which extend from the 2D that is n

used are:

– Linear extrusion or translational sweep,

and – Rotational sweep.

G t i C t ti M th

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Component model produced using

translational (linear) sweep (extrusion)

G t i C t ti M th

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omponent model produced using

translational (linear) sweep with taper in sweep

direction

G t i C t ti M th

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Component produced by the

rotational sweep technique


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he Boolean operators and their

effect on model construction

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Question

Thanks

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