Engineering Design. Conveying Design Through. Engineering Graphics & the

Transcription

1 Engineering Design Communication Conveying Design Through Graphics Chapter 1 Engineering g Graphics & the Design Process

2 Engineering Graphics Used to: VISUALIZE COMMUNICATE DOCUMENT MANUFACTURE design ideas.

3 Thinking Graphically The words of the language, as they are written or spoken, do not seem to play any role in my mechanism of thought. The psychical entities which seem to serve as elements in thought are certain signs and more or less clear images which can be voluntarily reproduced and combined-- this combinatory play seems to be the essential feature in productive thought before there is any connection with logical construction in words or other kinds of signs which are communicated to others --Albert Einstein

4 What is Engineering Design? The act of creating the specifications for a product or process that best satisfies the design criteria problem solving open ended dd

5 The Design Process Ideation/Sketching Refinement/Modeling Implementation & Documentation/ Detailed Dimensioned Drawings

6 Traditional Design Model Concurrent Design Model Design teams include sales, marketing, engineering, service, manufacturing & others. Accurate CAD database promotes communication.

7 Graphics are used throughout the stages of the Design Process

8 Problem Identification Stage: graphic skills are needed to interpret existing drawings.

9 Ideation Stage: freehand sketching is used to generate and record ideas

10 Decision Process/Design Selection: creating and interpreting charts, graphs, sketches, and drawings are needed skills

11 Refinement Stage: parametric modeling and 3D CAD skills are a valuable aid Boeing s tool for checking interferences in assemblies. These pins must match with their counterparts on the other side of the case. A formula in this model keeps the pins centered about the midline of the case.

12 Analysis: exporting model geometry to a variety of analysis software packages is a hlfl helpful aid Finite element analysis software can be used to analyze physical properties of the design and display the results graphically. Here higher stress concentrations are shown in hotter colors (yellow & red).

13 Implementation: understanding the model database and export formats can help in direct manufacture of parts One thousandth of a millimeter This micro-mechanicalmechanical hinge was manufactured directly from CAD data. See the case study in Chapter 4 for more details.

14 Documentation: good dimensioning practices; creation of section, auxiliary, and rendered edviews is needed.

15 Engineers use sketching to record their ideas. Most companies require a bound notebook written in ink for a permanent record. Designers Notebook

16 Notebook Instructions Dated entries record all diagrams, layouts, plans, new ideas, and other info Use engineering markers to create a permanent record Have 2 independent parties sign and date that they viewed your work

17 Parametric Modeling The different parts know how they relate to one another Their dimensions and geometric properties are defined in relation to each other through parameters

18 Advantages Models can be updated by changing the sizes and relationships that define the model, therefore one can update changes in design quickly Can get more cycles during refinement in less time -> a better design In defining i relationships that t build intelligence in the model, the engineer analyses the design intent more rigorously

19 Parameters A parameter is a named quantity whose value can change depending on the circumstances of its application Two basic parameters drive the model geometry Size Geometric

20 Parameters Ex. If width is twice the length the width parameter could be defined as W=2*L Unlike a variable, the parameter is never abstract

21 Feature-Based Modeling A feature is a basic unit of a parametric solid model When you specify the feature You specify geometric and size constraints If you were using a non-parametric modeler dl to change the size of a feature you would have to re-create it

22 Feature-Based Modeling Can you identify the features which make up this figure?

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24 Planning for Design Intent Design intent refers to the key dimensions and relationships that must be met by the part Do certain features of the part need to be aligned with other features? Where does the part fit into other parts? How will part change as design evolves?

25 Design Intent There are 4 key aspects of planning for design intent Identify part/assembly Define Key Features Identify relationships between features Identify dimensions that may change

26 Design Intent To first create a part, you would typically create a 2D sketch of the key shape of a feature as below (7.8)

27 Design Intent The software will assign constraints to your sketch Perpendicular Concentric Parallel Co-linear

28 Planning Parts Eg. Constraints assigned

29 Planning Parts Before generating g actual feature, you can review and change the geometric constraints and dimensions so they are what you intended How might you now generate a 3Df feature?

30 Planning Parts The model could be extruded, swept, revolved or blended as below