Professor abubakr lecture 1 cad 2016

06-Oct-15

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Helwan University

Faculty of Engineering

Mechanical Engineering Department

CAD

Dr. Abu Bakr Ibrahim Abd El Wahab

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Lecture 1 CAD 2014/2015

Professor Abubakr Lect 1 CAD 2016

06-Oct-15

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What is “Engineering Design Process” ?

“Design is the process of conceiving

or inventing ideas and تصور

communicating those ideas to others in

a form that is understood easily.”

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“A systematic process by which

solutions to the needs of humankind

are obtained.



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“The act of creating the specifications

for a product or process that best

satisfies the design criteria.


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Step 1 •Identify the need or problem

Step 2 •Research the need or problem

Step 3 •Develop possible solutions

Step 4 •Select the best possible solution


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Step 5 •Geometric Model

Step 6 •Test and evaluate the solutions

Step 7 •Communicate the solutions

Step 8 •Redesign

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Cost

Time

Once a design is released for production, the

cost of making changes grows exponentially

Late changes increase costs and extend

production schedules

Manufacturing

Documentation:

Drawings for

tool/fixtures,

instruction

manuals, etc. Design

Manufact

uring,

Assembly,

Testing Hard tooling

produced:

dies, molds,

fixtures, etc.

Product Development Cycle Costs


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Cost

Time

Manufacturing

Documentation:

Drawings for

tool/fixtures,

instruction

manuals, etc. Design

Manufact

uring,

Assembly,

Testing Hard tooling

produced:

dies, molds,

fixtures, etc.

Product Development Cycle Costs

Early decisions have large influence

Late changes are very costly

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What is the Geometric Model?

Collection of methods used to define the

shape and other geometric characteristics

of an object.



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Precise mathematical description of the

shape of a real object or to simulate some

process.


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Geometric Model


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How to Construct the Geometric Model?

Using CADD software

AutoCAD, TurboCAD, SolidWorks, Catia,

Master CAM, Pro/Engineer

14 Profile curve of the cup’s main body

Construct the Geometric Model


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15 Revolution axis of the cup’s main body

Construct the Geometric Model of cup’s main body

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Construct the Geometric Model: Profile curve of the

handle


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Construct the Geometric Model:

Sweep path of the handle

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Line drawing of the cup



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More Examples of Geometric Model


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Test and evaluate the solution - Engineering analysis:



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Test and evaluate the solution - Engineering analysis:

Evaluate each solution may require finite element

modeling, shape optimization, kinematics simulation,

circuit analysis, Computer Aided Inspection and

Heat analysis, …

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Finite-Element Method

Calculate stress, strain, displacement etc. at any

place in the model by solving a set of system

equations and shape functions on the mesh

Finite Element Shapes


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Meshing

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FEA of Our Cup

Stress distribution map


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An Example of FEM in Gas Tank Design

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Communicate the solution

Computer-aided drafting and design, CADD



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1. Increased accuracy

3. Easy to revise

2. Increased drawing speed

5. Built-in several analysis tools

6. Better presentation (Easy to visualize), Pan, rotate,

animate, shade, texture

4. Availability of drawing libraries

Advantages of CADD

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Draw

Modify

Sweeping

Revolve

Extruded Solid

Sectioning

Trim

Extend

Offset

Move

Copy

Stretch

Mirror

Trim

Erase

Fillet

Rotate

Chamfer

Array

Dimensioning

Layer concept

Limits

Zooming

Units

CADD

Capability


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Redesign

Step 8 •Redesign

Modify the design geometry (CAD again)

Get feedback from Test

Evaluate the solution

Engineering analysis and

Communication

Modify the design geometry accordingly

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Modifying the Design Geometry


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Modifying the Design Geometry

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Stress distribution map of the modified cup

FEA of the Modified Cup


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What after Engineering Design Process?

CAM

Step 1 • Identify the need or problem

Step 2 • Research the need or problem

Step 3 • Develop possible solutions

Step 4 • Select the best possible solution

Step 5 • Geometric Model

Step 6 • Test and evaluate the solutions

Step 7 • Communicate the solutions

Step 8 • Redesign

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CAM Manufacturing process planning

Plan, manage, and control manufacturing process

Numerical control (NC) machining

The technique of using programmed instructions to

control a machine tool that grinds, cuts, mills

punches, bends, or turns raw stock into the finished

part.

Rapid prototyping

Build a prototype of the part directly from the CAD

model as a stack of layers by means of laser or other

techniques.


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Figure 3. A schematic drawing of an SLA process.

StereoLithography

Rapid Prototyping

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CAD/CAM:

Integration of design and manufacturing

activities by means of computer systems.

The method of manufacturing a product is

a direct function of its design.


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ماهو الفرق بين كل من

CAD CAM CAD/CAM

CAD: Product design, engineering analysis, and

documentation of the design (e.g., drafting)

CAM: Process planning, NC part programming,

,material requirements planning, production

scheduling, computer production monitoring,

and computer process control, Inspection and

Assembly

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CAD/CAM denotes an integration of design

and manufacturing activities by means of

computer systems and computer science.

The method of manufacturing a product is a

direct function of its design.


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ماهو الفرق بين كل من

Conventional procedures & Ideal CAD system

Conventional procedures :Engineering drawings were

prepared by design draftsmen and then used by

manufacturing engineers to develop the process plan

(i.e., the route sheets).

Product design were separated from CAM

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Disadvantage of Conventional CAD procedures

ماهي عيوب ذلك

Two-step procedure was employed

Time consuming

Duplication of effort by design and

manufacturing personnel.


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Ideal CAD/CAM:

1.Automate CAD phases

2.Automate CAM phases

3.Direct link is established between CAD & CAM

4.Automate the transition from design to

manufacturing.

CAD CAM

Ideal Conventional procedures

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Ideal CAD/CAM system:

Take the design specification of the product as it

resides in the CAD

Automatically Convert it into a process plan for

making the product,

NC part program would be generated

automatically

NC program would then download directly to

the machine tool by means of a

telecommunications network.


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Case Study:

You saw very dirty window panels in your lecture room

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Cause:

Maybe, a person responsible to this job is lazy.

I don’t think so. I saw he worked hardly

.................

................


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Step 1 •Identify the need or problem

Step 2 •Research the need or problem

Step 3 •Develop possible solutions

Step 4 •Select the best possible solution



Step 7 •Communicate the solutions

Step 8 •Redesign

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You asked him, why don’t you clean those windows ?

He said it is impossible to clean those windows.

So, what do you think ?

Look at the windows again, then you will

understood his answer.

What are your findings ?


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?

?

You found that the windows have two glass panels

One is fixed to the top, another one is fixed to the

bottom of a window frame.

Both panels place offset with each other and their

free edge overlap about mid of the window’s height.

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Sorry, I cannot imagine about the window you have

explained.


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Okay, I will show you a sketch of the windows.

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Visualization

&

Communication

&

Documentation


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The Role of Graphics

Visualization Communication Documentation

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Sorry, I still do not understand why it is hard

to clean the window

Um.. . I will show you the side view of this

window.

The glass panel

is thin, so he omits

section lines !

Visualization

&

Communication

&

Documentation


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Ah.. I see. The offset distance is small, so he

can not access the opposite side of the

window and the overlapped zone.

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That is right !. If we do not solve this problem,

learning environment will become worse and

…….


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To design a device that can clean the opposite

side of glass panel and overlapping area

effectively.

Identify the need or problem

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Develop possible solutions.

1. Hire a cleaning service company.

2. Buy a usable device.

Individual Teamwork


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Develop possible solutions.

3. Design a homemade cleaning device.

5. ………………………

4. Redesign the window construction.

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Develop possible solutions. 3. Design a homemade cleaning device.

i- Modify from an existing solution.

ii. Ad hoc (Unplanned) solution. التصميم من ال شيئ


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Major functions of a device

1. Wash & Polish

2. Wipe

Solution Feature

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Would you like to combine both functions

into a single device or :?

1- Single device

2- Single device but has a changeable part

3- Two devices:

One for wash & polish, another for wipe.

Assume you (or your team) choose:

Single device


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Wash

Polish

Wipe

Hold (by user)

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Easy to use.

Should not rust.

Not too expensive

Not too heavy.

Can insert between the panels.


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What should be an appropriate form of part(s)

to do the required functions?

What material is the part should be made of ?

How parts are assembled ?

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Function

What material is the part

should be made of ?

What should be an

appropriate form of

part(s) to do the

required functions?

How parts are assembled ?

Not too heavy.

Not too expensive.

Can insert between the panels.

Hold

(by user)

Polish

Should not rust.

Easy to use.


Wash

Wipe


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“Design a homemade cleaning device”

Is your decision is the best solution ?

Criteria !!!!

Evaluate each solution against the criteria

and select the best one.

Brainstorming

Brainstorming expands one’s thinking to

include all the dimensions of a problem

or its solution

Brainstorming is used to help a group

create as many ideas as possible in

as short a time as possible


http://images.google.com.eg/imgres?imgurl=http://3quarksdaily.blogs.com/3quarksdaily/images/brainstorming.gif&imgrefurl=http://3quarksdaily.blogs.com/3quarksdaily/2006/03/the_problem_wit.html&h=198&w=193&sz=12&hl=en&start=8&um=1&tbnid=FVR2NaLwWx6bjM:&tbnh=104&tbnw=101&prev=/images?q%3DBrainstorming%26um%3D1%26hl%3Den%26newwindow%3D1%26sa%3DN

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Goal wishing -Free-thinking

It is totally without regard to feasibility -

non-judgmental

New ideas often start out as totally

ridiculous

Some of the more important things to do and avoid:

a. Do go first for quantity

b. Avoid evaluating (looking for quality)-that comes

later

c. Avoid assumptions about limits, restrictions etc.

d. Do write everything down.


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e. Write down and keep visible the central topic

f. Don’t criticize ideas or suggestions

g. Write down all ideas as spoken, and keep them

visible to the participants

h. Every participant/student is asked to

present an idea

i. Participant/Student give ideas as they

come to mind


http://images.google.com.eg/imgres?imgurl=http://www1.istockphoto.com/file_thumbview_approve/4076495/2/istockphoto_4076495_flip_chart_isolated.jpg&imgrefurl=http://www.istockphoto.com/file_closeup/object/4076495_flip_chart_isolated.php?id%3D4076495&h=380&w=284&sz=14&hl=en&start=1&um=1&tbnid=HmupMVK72Ig8aM:&tbnh=123&tbnw=92&prev=/images?q%3Dflip%2Bchart%26um%3D1%26hl%3Den%26newwindow%3D1%26sa%3DN

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Possible solutions.

1.

2.

3.

5.

4.

Possible solutions.

1. Hire a cleaning service company.

2. Buy a usable device.

3. Design a homemade cleaning device.

5. ………………………

4. Redesign the window construction.


http://www.google.com.eg/imgres?imgurl=http://www.universitybusiness.com/sites/default/files/Wausau1.jpg&imgrefurl=http://www.universitybusiness.com/article/1st-annual-readers%E2%80%99-choice-awards&usg=__KGpbwxTf9d9no2RdYeRINYIKapM=&h=1200&w=951&sz=150&hl=en&start=295&sig2=6VaOJFWYhqoYVkm5GV58MQ&zoom=1&tbnid=TJt4XJp6ccTeeM:&tbnh=150&tbnw=119&ei=0HdcUaiPFsqxPN-zgcgC&um=1&itbs=1&sa=X&ved=0CEcQrQMwDjiYAg

http://www.google.com.eg/imgres?imgurl=http://www.universitybusiness.com/sites/default/files/Wausau1.jpg&imgrefurl=http://www.universitybusiness.com/article/1st-annual-readers%E2%80%99-choice-awards&usg=__KGpbwxTf9d9no2RdYeRINYIKapM=&h=1200&w=951&sz=150&hl=en&start=295&sig2=6VaOJFWYhqoYVkm5GV58MQ&zoom=1&tbnid=TJt4XJp6ccTeeM:&tbnh=150&tbnw=119&ei=0HdcUaiPFsqxPN-zgcgC&um=1&itbs=1&sa=X&ved=0CEcQrQMwDjiYAg

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C

Assume you (or your team), Choose the solution C

A B

C

Example of mathematical analysis Operation


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Evaluate each solution against the criteria and

select the best one

This is the initial evaluation step

Discuss the Pro فى الجانب المؤيد /con الموقف السلبي

Picks one or more directions that hold some

attract

States the concerns.

Removing obstacles or concerns

As concerns are addressed, they get a little

more realistic


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Cost Weight … Size Solutions

Ease of operation

Evaluate each solution against the criteria and select the best one.

Criteria

A B

C

Mathematical analysis

Computer simulation

Build and test a prototype

Tools for evaluating the solutions :

Freehand

sketching is

used to

represent

rough ideas.

Document the solution.


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CAD Homework #1

1- What are the most important components of Engineering Design

Process?

2- Describe product development cycle costs and the outcome from

the cost – time relationship.

3- How to construct the Prototype / Geometric Model? . Give an

example

4- How to evaluate each solution

5- In the steps that you answer in 1, which one uses Computer-aided

drafting tool, which one uses Finite-Element tool, and which one

uses CAM tool?

6- What is the most widely used CADD Capabilites?

7- What is the most widely used CADD software ?

8- Describe the difference between Conventional procedures &

Ideal CAD procedures?

9- What is Numerical Control Machining?

10- What are the steps of brain storming cession?


Professor abubakr lecture 1 cad 2016

Design

Transcript of Professor abubakr lecture 1 cad 2016