Modeling

1.   Understand the terminology used in 3-D modeling. All sections.

2.   Define the most common types of 3-D modeling systems. p. 156

3.  Describe the similarities and differences between constraint-based modeling and direct modeling. p. 156

4.   Apply Boolean operations to 3-D objects. p. 153

5.  Understand the role that planning plays in building a constraint-based model. p. 157

6.  Understand how feature order affects feature editing and final model geometry. pp. 174-175

7.   Apply generalized sweeps to the creation of model features. pp. 161-163

8.   Apply construction geometry in the support of feature creation. pp. 163-164

9.   Apply constraints to a feature profile. p. 156

10. Apply feature duplication to model construction. p. 178

11. Identify the elements used to define a view of a 3-D model. p. 180

12. Understand how model data associativity supports engineering design and analysis. pp. 153-154

13. Generate 2-D documentation from a 3-D model. pp. 183-184

14. Construct assemblies from part and subassembly models. pp. 170-180

15.  Define the types of analyses that can be used with 3-D models. pp. 185-187

16.  Understand how CAM information is derived from 3-D models. pp. 185-187

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1.   What is a nonmanifold object? Sketch an example of one.

Manifold objects unambiguously divide a region into inside and outside. Nonmanifold objects don't do this. p134

2.   Describe the differences and similarities between B-rep models and CSG models; do the same for wireframe models and B-rep models.

CSG models use solid primitives and half spaces related by Boolean operations in a binary tree data structure.  B-rep models define a solid region by surfaces, edges, and vertices.  Wireframe models do not define a volume, but describe just the edges and vertices of a 3-D model. pp135-138

3.   Define the three types of Boolean operations, and sketch examples of each one. Can you derive the same final object using different Boolean operations and/or primitives?

p137

4.   What is "design intent"? Why does this play a role in planning the construction of a constraint-based model?

Changes in geometry of a feature should create model feedback or further changes in the model which reflect design performance or manufacturing constraints of the product. p139

5.   What is the difference between unidirectional and bidirectional associativity? What are the advantages and disadvantages of bidirectional associativity?

In a sweeping operation, a closed polygon, called a profile, is drawn on a plane and is moved or swept along a defined path for a defined length.  Linear, revolved, path-based, and blend. pp142-3

6.   What are the basic elements of a generalized sweep? Describe the major types of generalized sweeps used in feature creation.

Workplanes define the location and orientation of the profile sketch and construction geometry relative to the model and world coordinate system. Through, Offset/parallel, Angle, Point or edge and orientation, Tangent and orientation, Axes and points.  p143

7.   What are sketch planes used for? What are five ways a sketch plane can be defined?

These two types of constraints differ as to whether the modeling system infers the constraint based on the way the sketch was drawn, or whether the operator has to explicitly apply the constraint to the sketch. Closure (connected edges), Segment overlap, Endpoint/line overlap, Tangency, Parallelism, perpendicularity, Same size, Coincident.  pp147-8

8.   Give an example of a parent-child relationship. How is a feature tree used to identify parent-child relationships?

A child feature is defined relative to a parent feature through geometric definitions such as constraints, alignment, or workplanes.  Child features exist below their parent features on a feature tree.  pp159-160

9.   What are the two primary types of duplication methods? What input parameters are needed to define each one?

Linear and radial arrays.  Linear arrays need the number of copies to be made in each of two orthogonal dimensions and the offset in each of these dimensions.  Radial arrays need a rotation axis, radial distance from the axis, number of copies, and the angular offset.  p162

10. What are the elements used to define a view of a 3-D model? Which types of view commands don't change the projection of the model?

Model (object), viewer (camera), and projection (view) plane.  Panning and zooming don't change the projection in parallel projection.  pp163, 166

11. How is the base view used in generating multiviews from a 3-D model?

With unidirectional associativity, the supporting application’s data can be altered by changing the 3-D model, but not vice versa. With bi-directional associativity, changes in either the 3-D model or data in the supporting application will affect the other.  p163-164

12. Define the types of analyses that can be used with 3-D models. Will all of these always be used when designing a part?

13.  What advantages are there for using data from a 3-D model when analyzing the manufacture of a part?

Engineering Geometry

1.   Describe the importance of engineering geometry in the engineering design process. p. 92

2.   Describe coordinate geometry and coordinate systems and apply them to CAD. pp. 92-98

3.   Explain the right-hand rule. pp. 95-96

4.   List the major categories of geometric entities. pp. 99-108

5.   Explain and construct the geometric conditions that occur between lines. pp. 100-103

6.   Explain and construct tangent conditions between lines and curves. pp. 103-105

7.   Describe the process of constraining sketch geometry for use in the solid-modeling process. pp. 115-120

8.      List and describe surface geometric forms. pp. 124-130

9.      Describe engineering applications of geometry. p. 110, pp. 112-113

10.  Describe wireframe and surface 3-D modeling. pp. 132-135

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Questions:

1.     Define engineering geometry, and describe its importance to engineering design.

Geometry provides the building blocks for the engineering design process. p78

2.     Describe how coordinate space relates to engineering design.

Engineering geometry has to be referenced to a coordinate system in order to both define its form and to relate to other geometry. p79

3.     Explain the right-hand rule, using sketches.

p81

4.     How is a curved line different from a straight line?

A straight line is generated by a point moving in a constant direction.  A curved line is generated by a point moving in a constantly changing direction. p89

5.     Describe an engineering application for a parabola and for a hyperbola.

Parabolas and hyperbolas are used to focus electromagnetic radiation. pp92-6

6.     What is the difference between a plane and a surface?

A surface is a finite portion of a plane. p100

7.     List six quadrilaterals.

Square, rectangle, rhombus, rhomboid, trapezoid, and trapezium. pp101

8.     Define concentric circles.

Circles of unequal radii which share the same center point. p92

9.     Define a tangent.

A line which touches a circle at one and only one point. p90

10.  Describe an engineering application for an ellipse.

Used in the design of arched ceilings. p100

11.  List and sketch four polygonal prisms.

Right prism, pentagonal prism, cube, triangular prism, and oblique parallelepiped. p109

12.  Define a warped surface.

A double curved ruled 3-D surface generated by a straight line moving such that any two consecutive positions of the line are skewed. p104

13.  List the major categories of geometric forms.

Points, lines, surfaces, and solids. p85

14.  Sketch and label the various conditions that can occur between two lines.

Parallel, non parallel, perpendicular, tangent, and intersecting. p89

15.  Sketch and label the various tangent conditions that can occur between lines and curves and between two curves.

p89

16.  Sketch a circle and label the important parts.

p92

17.  Describe the process of sketching and constraining engineering economy for 3-D modeling.

Complex curves described by higher order mathematical functions, such as Bezier or B-spline curves. p99

    18.    List and define freeform curves

The graphics of randomly generated geometry that exhibit a degree of self-similarity. p110

19.  Describe fractals.

Vertices and edges. No. p112

20.     What is the minimum information needed to define a true wireframe model? Is there enough information in a wireframe model to determine which edges are hidden?

21.     Describe the four common methods used to create 3-D surfaces.

22.     Early technical drawings were often crude and hard to understand until the development of a formal projection system that occurred during what period of time?

Sketch

1.      Define technical sketching. p. 56

2.      Describe how sketching integrates into the design process. pp. 56-58

3.      Identify and define two types of sketches. pp. 56-57

4.      Create a design sketch using pencil or computer. pp. 58-60

5.      Identify and use sketching tools. pp. 62-68

6.      Use grid paper to create sketches. pp. 70-75

7.      Lay out a sketch using proportions. p. 70

8.      Use sketching to draw lines, circles, arcs, and curves. pp. 65-69

9.   Use various sketching techniques, such as contour and negative space sketching, to improve your sketching technique. pp. 62-65

10.  Describe how sketching is used for constraint-based modeling. pp. 76-80

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1. Define and describe the uses for technical sketching.

Technical sketching is the process of producing a rough, preliminary drawing representing the main features of a product or structure.  Technical sketches are used extensively in the first (ideation) stage of the design process.  p. 56

2. Define an ideation sketch and explain how it differs from a document sketch.

An ideation sketch is a simplified sketch used to capture a fleeting idea.  A document

sketch may follow some or all of the conventions of a more formal mechanical drawing. pp. 56-7

3. List the four types of sketches, grouped by projection method. Sketch an example of each type.

Multiview, isometric, oblique, perspective. The last three are all pictorial sketches. p. 58

4. Describe the major differences between parallel and perspective projection.

Perspective sketches are more realistic, but harder to draw properly. Parallel projection is used in multiview, isometric, and oblique sketches. p. 58

5. Define multiview drawing and make a sketch of one.

Multiview sketches present the object in a series of projections, each one showing only two of the object’s three dimensions. p. 58

6. Define principal view.

The view that most clearly describes the features of the object. From this view, additional multiview projections are generated.  (Chap 5)

7. Describe the precedence of lines.

Different lines represent different types of features on a drawing. If two types of lines overlap, certain types of lines take precedence. The order of precedence is: visible -> hidden -> center.  (Chap 5)

Geometry Communication-Introduction

Objectives AND OVERVIEW

1.   Describe why the use of graphics is an effective means of communicating when designing. pp. 2-7

2.   Describe the engineering design process and the role graphics play. pp. 7-16

3.   Describe the model-centered design process. pp. 10-11

4.   Explain the role 3-D modeling plays in the engineering design process. p. 29

5.   Describe the role of CM, PLM, and PDM in the engineering enterprise. p. 13

6.      Describe the important types of graphics used to support the engineering design process. pp. 17-19

7.      List and describe the modeling techniques used in design. p. 21

8.      List and describe the analysis techniques used in design. p. 25

9.      Describe additional technologies used to capture data, output, and visualize 3-D models. pp. 45-51

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1. Explain the difference between engineers and technologists.

Engineers are creative (usually formally educated) people who use technical means to solve problems.  They design products, systems, devices, and structures to improve our living conditions.  Technologists work with and for engineers and are concerned with the practical aspects of engineering in planning and production.    p. 3

2. How can visualizing help an engineer in the design process?

Visualizing allows design engineers to mentally picture things in their minds that do not exist.  Additionally, good visualization skills allow them to visualize motion, change the form or shape, and move around and picture the inside of the mental image of the design problem.    p. 6

3. What are the three main areas or phases of the model-centered design process?  Do the activities in these areas happen in a sequential fashion?

The three main areas or phases of the model-centered design process are ideation, refinement, and implementation.  Model-centered engineering design is a nonlinear team approach to design that brings together the input, processes, and output elements necessary to produce a product.    pp. 10-11

4. Explain how PLM is used in the design process.  What is its relationship to CIC?

Product Lifecycle Management (PLM) is an organizational model that involves all departments in a company, including the engineering design process, in the design and manufacture of a product.  In addition to CAD software, other specialized software products and technologies are used in conjunction.  PLM is used as a basis for creating the accumulated corporate intellectural capital (CIC) of a company or organization.     pp. 13-15

5. Outline the steps of problem identification in the ideation phase.

Problem identification is an ideation process consisting of the following six elements:  problem statement, research, data gathering, objectives, limitations, and scheduling.    p17

6. What kinds of graphics are used in the ideation phase?

In the ideation phase the types of graphics used include charts, graphs, ideation sketches and drawings, design drawings, analysis and concept models, and presentation graphics.    pp. 17-19

7. What is the designer’s notebook?  How is it used?

A designer’s notebook is similar to a diary and contains meticulous notes and sketches that are organized to show the path of development for a product and process.  A well-documented notebook contains notes, calculations, signatures, and dates making an accurate document for an original design.    pp. 19-20

8. Outline the main activities in the refinement phase.

Refinement is a repetitive (iterative or cyclical) process used to test a preliminary design and makes use of the following:  modeling, design analysis, and design visualization.    pp. 20-21

9. Describe the different kinds of models used in the design process.

In engineering design, models are classified as either descriptive or predictive and are described in further detail as follows:  Descriptive models can consist of 3-D CAD or physical scale models used simply to visually represent the design.  Predictive models can be mathematical or virtual 3-D CAD models that can be used to analyze the motion or physical properties of the design.    p. 21

10. Describe the different kinds of analysis techniques used in the design process.

Typical types of analysis performed on designs include:  property analysis, mechanism analysis, functional analysis, human factors analysis, aesthetic analysis, market analysis, and financial analysis.    p. 25

11. Outline the three ways the 3-D model database can be used in the implementation phase.

(1) Production – 3-D CAD models are used to run machine tools and make parts and lay out the factory floor.  (2) Marketing – 3-D CAD models are used for illustrations, presentation graphics, and advertising.  (3)  Service & documentation – 3-D CAD models are used for service manuals, training, and assembly instructions.    pp. 29-33

12. What kinds of documentation might be produced as part of the design process?

Design process documentation can include 2-D drawings, 3-D design models, presentation drawings, and illustrations.    p. 33

13. Explain the role of PDM in the design process.  What is the relationship of ERP to PDM?

Product data management (PDM) is the name given to specific computer-based tools used to track CAD or office documents with user-defined data fields, such as revisions, authors, date, etc., in the development and manufacture of a product.  Within PDM, enterprise resource planning (ERP) is a system that specifically focuses on the ordering of material and planning for the manufacture of a product.    pp. 38-39

14. What is the difference between conventions and standards?

Conventions are accepted practices, rules, or methods used in the production of visual elements, such as dashed lines or hidden features, on a multiview drawing.  Standards are sets of rules (formal; ANSI or ISO) that govern how technical drawings are represented.    p. 42

15. Describe two reverse engineering techniques.

Two reverse engineering techniques are (1) the use of coordinate measuring machines (CMM) to physically take key dimensions from an existing object or part and (2) the use of laser scanning to make critical measurements from existing parts.   p. 44

16. Describe two different rapid prototyping technologies.

Two different forms of rapid prototyping technology are:  (1)  Stereolithography (SLA) – using a laser-focused beam to harden a light-sensitive polymer, and (2) fused deposition modeling (FDM) – using a molten plastic to deposit a series of very thin layers to build and create a part.    p. 46

17. Explain why an enterprise might want to store data in an off-site data warehouse.

One critical reason for using off-site data warehousing to store data is to protect against loss from fire or other catastrophes at the company’s engineering center.    p. 47

18. Describe two different VR display techniques.

Two different VR display techniques are (1) the use of head-mounted displays (HDM) for individual users and (2) multiple projection systems called computer augemented virtual environments (CAVEs) for multiple users in a larger physical space.    p. 50