ME110- Introduction to CAD

Craig R. RonaldGavett 244

Course Format PTC Creo

» Industry recognized leader in mechanical design software.

Focus on solid modeling, detailing and assemblies.

Design Examples

KTM Motorcycles

Astin Martin

Artificial Heart

Design Examples

Komatsu Construction

Guitars

About the Instructor MS Mechanical Engineering U of R

1990 Taught ME110 since 1987 Used PTC Creo since 1997

Importance of Course Only a 2 credit course but... Teaches the language of

engineering Skill that is most likely to help job

search

Web Site http://www.me.rochester.edu/courses/ME110 Link is on Blackboard The web site will be kept up to date Check frequently! You are responsible

for knowing the information on the site.

Blackboard Log on at: learn.rochester.edu Assignments Grades

Course Outline Phone numbers 259-6119 Cell(‘til

10PM) E-mail: ronald@me.rochester.edu

Saving Work for Course Flash Drive

– you will need to have a USB flash drive by next lecture.

– All HW and test files must be saved– Must be able to show the original files

in case of grading disputes.

Academic Honesty All assignments and activities associated with this

course must be performed in accordance with the University of Rochester's Academic Honesty Policy. 

Suspected violations will be pursued vigorously following the College’s procedures for suspected cases of academic dishonesty.– Collaboration on homework is encouraged– Each student must create and submit their own file while

logged onto their own NetID– Sharing files, data, or accounts on homework or tests is

prohibited.

ConclusionSAVE YOUR WORKDON’T CHEAT

Six View Orthographic Projection

Three views are usually sufficient

Choice of views– least hidden

lines– clarity– only necessary

views

Precedence of Lines Visible Hidden Center

Meaning of lines– intersection of 2 surfaces– edge view of a surface– contour of a curved surface

Section Views Use section

views to eliminate hidden lines.

All visible lines behind plane shown.

Hidden lines are rarely shown.

Types of CAD systems Wireframe- modeling the curves of the

part Surface modeling- Model the surfaces of

the part, but without knowledge of material.

Solid modeling- full solid representation Parametric Modeling- dimension driven

solid modeling.

Solid Modeling What is a solid model?

– A three dimensional representation of geometry that includes the shape definition of the geometry as well as a definition of inside and outside.

Why use a solid modeler? Intelligent modeling- modeler can

understand concept like through, through until, etc.

Accurate Detailing– Hidden lines– Section views– Auxiliary views

Manufacturing- Tool paths may be made directly

from the model.

Interference checking

Finite Element Analysis Ability to do Deflection and stress

analysis on complex parts/assemblies.

Complex problems are discritized into simple shapes.

Rapid Prototyping Stereo Lithography

– Light setting polymer is built up layer by layer with a laser.

3D Printing Plastic printing from a spool of

material

3D Printing Inkjet printer glues together layers

of Stainless steel powder. Sintering binds the powder.

Demo

Types of Solid Modeling B-REP– Boundary representation

– The solid is defined by the surfaces bounding the volume as well as inside and outside definition. (outward unit normal)

Types of Solid Modeling CSG- Constructive Solid

Geometry– Primitive solid shapes joined together with Boolean

operators define the solid. The model is stored with a tree structure.

– Boolean operators are three-dimensional set operators (union, difference, and intersection).

Set Theory

Union Difference

Intersection

CSG- Constructive Solid Geometry