Fundamentals of 3D modeling

Unit-i
Fundamentals of 3d modeling
S.G.R. Education Foundation
G H RAISONI COLLEGE OF ENGINEERING AND MANAGEMENT
AHMEDNAGAR
NAAC ACCREDITED
(APPROVED BY AICTE, NEW DELHI, RECOGNIZED BY GOVT. OF MAHARASHTRA & AFFILIATED TO SAVITRIBAI PHULE PUNE UNIVERSITY)
- Prof. Aniket V. Joshi
Asst. Professor
Mechanical Engineering Department
GHRCEM, A’Nagar.

introduction
1. What is Design?
Design is the human power to imagine, plan, and realize
products that serve human beings.
Design is a complete prototype with analysis and
manufacturing.
The design process
Steps of the Conventional Design Process:
1. Recognition of need
- Someone recognizes the need that can be satisfied by a new
design.
2. Problem definition
- Specification of the item.
2
AVJ GHRCEM AHMEDNAGAR

introduction
3. Synthesis
- creation and conceptualization
4. Analysis and optimization
- the concept is analyzed and redesigned
5. Evaluation
- compare design against original specification.
6. Presentation
- documenting the design (e.g. drawing)
AVJ GHRCEM AHMEDNAGAR 3

Problem Identification
Synthesis
Evaluation
Analysis and Optimization
Presentation
Recognition of need
Fig: Stages in Design Process

introduction
What is Drawings?
- Drawing is rough sketch which give some
message or information about
production. (like shape of product)
What is Drafting ?
- Drafting is a language of engineers with
exact scaling, dimension, measurements,
accuracy and with standard like ISO,
ASEE…etc.

• CAD - Computer Aided Design and Computer Aided
Drafting.
• It’s an integration of computer science techniques
for engineering design.
• The term Computer Aided Design characterizes any
design activity which incorporates an electronic
computing machine in the process of development,
analysis or modification and optimization of design.
Computer Aided Design (CAD)

Computer Aided Design (CAD)
 What does mechanical engineers do in CAD?
– Mechanical engineers do drafting and design and
prototype testing (analysis) operation in CAD.
– Use to creates graphic representation of physical
object.
 Generally the main function of CAD is used to
– Create graphic representation (create 2D/3D drafting)
– 3D modeling (individual component modeling and
Assembly modeling)
– Used for analysis (stress analysis, kinematic
analysis,..etc.)
– Used for simulation the system (collusion simulation, robotic
simulation.. etc.)

Application of CAD in
mechanical Engineering
Automotive industry
Aerospace and air craft industry
Textile industry
Tool and die making industry
Die manufacturing industry
Welding and cutting industry
Automobile industry
Jigs and fixture manufacturing..etc.

Advantage of CAD over
manual Drafting
• Easy to draw
• Less time consumption
• More accuracy and precision
• Quick access
• Easier modification
• Good appearance in output
• Storage facility
• Less prone error
• Easy to share accurate information
• Better communication between users.
• Higher performance
• Increase efficiency of designers work.

Product life cycle

Product life cycle
 2 main processes: Design + Manufacturing
 2 sub-processes of design: Synthesis + Analysis
 The end goal of the synthesis is a conceptual
design of the prospective product
 The analysis evaluate the performance ofthe
expected product
 Computer prototypes: Less expensive and faster to
generate

Product life cycle
o Manufacturing process begins with the process
planning.
o Process planning is the backbone of the
manufacturing process.
o The outcome of the process planning is a production
plan, tools procurement, material order, and machine
programming.

CAD tools in the design process of
Product Cycle

CAD tools in the design
process of Product Cycle
1. Product Concept: Product cycle begins with product
concept. The product concept is cultivated, refined,
analysed and improved.
2. Computer Aided Design: computer aided design of the
product concept is carried out using the various cad tools
such as: Geometric Modeling, FEA and Simulation.
3. Computer aided drafting and documentation: 2D drawing
containing detailed description and information is
generated from 3D model.
4. Computer Aided Process Planning (CAPP): Process plan is
carried out using geometrical database of product. Tool
design and tool layout also carried out using computers.

CAD tools in the design
process of Product Cycle
5. Computer Assisted Production Planning: followed by
CAPP.
6. Computer Aided Manufacturing: Automatic tool path
generated for CNC machines. Computer controlled robots
and material handling equipments are also used in
production.
7. Computer Aided Quality Control: Computers are used for
inspection and performance testing of the products and its
components.
8. Computer Aided Marketing: Digital marketing.
9. Computer Aided Customer Feedback: online feedback from
the customers is taken.

Problem Identification
Synthesis
Evaluation
Analysis and Optimization
Presentation
Recognition of need
Design Process
Geometric Modeling
Engg. Analysis
Evaluation & Design Review
Automated Drafting
Computer
Aided
Design

SCOPE OF CAD
1. Geometric modeling: 2D, 3D models of Components,
assemblies and systems.
2. Finite Element Analysis: FEA software used for stress
analysis, thermal analysis and vibration analysis.
3. Simulation: simulation software are used for evaluation of
engineering systems.
4. Automated Drafting: creates 2D drawing from geometric
model.

Software modules
• Operating System (OS) Module:
Every OS provides its own library to programmers.
• Graphical User Interface (GUI), model representation
capabilities are dependent on these library files.
• OS can be paid or open source.
Ex: Microsoft Windows, Red Hat, Linux, Apple Macintosh,
etc..
• All CAD software developers prepare their products which
can be installed on any OS.
• Functions of software on any OS are same but GUI may be
different.

Software modules
 Different software modules are:
a. Geometric Module: creating sketch, modeling, assembly,
presenting the model in different views, their drawings, printing
and exporting.
b. Application Module: FEA, CFD, Thermal Analysis, Crash analysis,
electromagnetic, animation, simulation and optimization,
Applications in MFG: CIM, CNC, 3D Printing, etc.
c. Programming Module: allows user to programme their
requirements, needs knowledge of workspace and
programming languages like, C++, java, etc.
d. Communication Module: for exchange of geometrical data for
various applications using different file formats like STEP
(STandard for the Exchange of Product model data), IGES
(Initial Graphics Exchange Specification), etc..

SOFTWARE AVAILABLE FOR
CAD/CAM
3D Modeling Software: CATIA, CREO, SOLIDEDGE,
SOLIDWORKS, INVENTOR, etc..
Finite Element Analysis software: ANSYS, NASTRAN,
HYPERWORKS, ADINA, ALGOR, etc..
CAM Software: MASTERCAM, DELCAM, VISUALMILL,
ONECNC, etc..

Hardware requirements for
computer aided design
• A typical CAD system include following hardware
components:
a. CAD Workstations
b. Output devices
c. Central Processing Unit (CPU)
d. Storage Devices (Memory Units)

Hardware requirements for
computer aided design
CAD workstation consist of:
a. Graphics display device
b. Input devices
CAD workstation must accomplish following functions:
 It must interface with CPU
 It must generate a steady graphic image
 It must create digital description of graphic image
 It must convert input commands into operating functions
 It must be interface between the user and CAD system

3d modeling
 Geometric Modeling-
 complete representation of an object with graphical and
non-graphical information.
 Generates the mathematical representation of the
geometry and non-geometry of :
a. An object in the computer database
b. The image of an object on the graphics screen

3d modeling
Generation of graphical image by geometric modeling:
Three types of input commands are used:
a. Basic geometric entities: points, lines, and circles
b. Transformations of above mentioned entities
c. Various graphic elements to be joined into the desired
shape of the object.

Types of geometric modeling
Methods of Geometric Modeling
Wireframe Modeling
2D Wireframe Modeling
2 +(1/2) D Wireframe Modeling
3D Wireframe Modeling
Surface Modeling
Solid Modeling

Wire-frame modeling
 2 dimensional entities are used, such as: points, straight
lines, curves, polygons, circles etc..
 Model appears like a frame constructed out of wire
 Simplest and oldest method

Types of wire frame modeling
2D wire-frame Modeling:
 Suitable for flat objects
2D wire-frame model

2.5 D Wire-frame modeling:
 Represents 3 dimensional object
 Does not have side wall details
2.5 D wire-frame model

3D wire-frame Modeling:
• Used to represent 3D objects with side wall details
• Confusing for complicated models
• To overcome confusion, dashed lines used hidden edges or
hidden lines removed automatically
3D wire-frame Modeling

Advantages of wire-frame
modeling
 Simplest to construct
 Requires less computer memory
 Forms the basis for surface models
 CPU time required to retrieve, edit or update the wire-
frame model is less compared to surface or solid models.

Limitations of wire-frame
modeling
 Very difficult and time consuming to generate wire-frame
models of complicated objects.
 Requires more input data compared to solid models.
 Very confusing for complicated objects especially when
there is no facility available for automatic hidden lines.
 Not possible to calculate properties such as: mass, volume,
moment of inertia, etc.
 Not suitable for applications like generating cross sections,
checking interference between mating parts, NC tool path
generation, process planning, etc..
 More ambiguous representation than surface and solid
models

Surface modeling
 Need of surface modeling:
To represent complex objects such as: automotive bodies,
aircraft bodies, ship bodies, casting and dies, etc..
 Surface Model:
 generated by using wire-frame entities or curves (analytic
or synthetic).
 May require one wire-frame entity or generated surface of
revolution
 May require two wire-frame entities to generate a ruled
surface

Surface modeling
Surface of Revolution Ruled Surface

Surface modeling
 Mesh of surface model:
 To assist the visualization of object on graphical display,
artificial fair lines called mesh are added on the surface.
 Mesh size is controlled by user.
 Finer mesh size requires longer CPU time to construct
surface model and to update the graphical display.
 Finer mesh size does not improve the mathematical
representation, it only improves its visualization.

Surface modeling
 Rendering Features:
 Rendering enhances the aesthetic appeal of the object. It
gives
a. Color effects
b. Object appears like made of brass or appear corroded
c. Provides light effects such as spot lights, ambient lights,
etc..
 Surface modeling can be used for NC/ CNC tool path
generation.

Solid modeling
• Easiest and most advanced method of geometric modeling
• Solid models contains both geometric data and topological
information.
• Solid models can be converted into wire-frame models. It is
not possible to convert wire-frame model into solid model.
Solid Model

VRML web based viewing
 Introduction to VRML:
• Virtual Reality Modeling Language
• Enables to display and manipulate the CAD models in a web
browser. (object can be rotated to view invisible sides).
• There is no need of CAD software to open file saved in
VRML format.
• CAD model can be viewed in free ware like: Online 3D
viewer, Cortona 3D viewer, etc..
• To see VRML files, it is necessary to install VRML browser or
plug-in.
• File extension- WRL

 How to use:
 From any CAD software, export CAD file using ‘EXPORT’ or
‘SAVE AS’ command
 Exported file can be opened in web browser having VRML
plug-in.
 The model can be rotated or moved, similar to CAD
software.

 Types of VRML plug-in
for general browser:
 For Google Chrome:
3D view, Cortona 3D
viewer
 For Mozilla Firefox:
Free WRL, Cortona
3D viewer

 Advantages/ Features:
 Can manipulate 3D data set in an easy and standardized
method.
 Does not require CAD software. CAD model saved in VRML
format can be viewed 3 dimensionally.
 Free ware VRML are available on the web.
 VRML is accessible via standard browser format.

 Limitations:
 For complex 3D geometry higher network transmissions
rates are required.
 Powerful local rendering capabilities are necessary to view
complicated shaped objects.
 VRML is not a replacement of CAD/CAM Product model as
VRML facilitates only one way translation.
 Applications:
 Useful in distance vocational learning.
 Used for complex 3D representation in creation of scenes,
product or Virtual Reality applications.
 Used in automated manufacturing systems Design and
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Fundamentals of 3D modeling

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