design intent: effectively using constraints in solidworks lecture 9, part 2 iat 106 spatial...
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Design Intent: Effectively using Constraints in SolidWorks
Lecture 9, Part 2
IAT 106 Spatial Thinking and Communicating
Examples
http://idletigers.files.wordpress.com/2008/01/lego-bricks-high-resolution.jpg
http://www.allanblock.com/retainingwalls/Installation/Landscape/build/image/AngleOfRepose76.jpg
http://www.mcs.surrey.ac.uk/Personal/R.Knott/Fibonacci/fibnat.html
http://www.unbeatable.co.uk/articles/jvclt46dz7.jpg
16:9
IAT106: Design Intent M9 Pt2.3
Objectives
• Introduce concept of design intent
• Use constraints in SolidWorks to match design intent
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Design Intent
• What you intend a design to do.
• Some intentions can be modeled.
• Others not.
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Modelable Design Intent
• I intend that the Centre of Effort align with the Centre of Lateral Resistance.
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Un-modelable Design Intent
• I intend that a new boat design transforms the sport of sailing.
M9 Pt 2.7IAT 106: Design Intent
A Square?• What is a square?
Square in SolidWorks1. Draw rectangle2. [Select one edge and define length
using Smart Dimension]
3. Select perpendicular edge, set relationship with previous edge as ‘equal’
4. Result: square!
A rectangle where sides and diagonals meet at right angles; or
All sides have equal size|AB| = |BC| = |CD| = |DA|And meet at right angles
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Constraint
Constraint refers to the degree of logical or mathematical dependence between or among variables.
In modeling we define geometry of objects, particularly:
– Size– Location– Orientation
Example model for demonstrating constraints
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Constraints in Parts
• Often think of constraints when creating assemblies
• But, constraints are just as useful when creating parts
http://www.seacadtech.com/torimoto/
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Types of Constraints
Size Location Orientation
Explicitdefined by user
AD = ABR = AB / 4
Center point on midpoint of diagonal
Angle DAB and ABC = 90°
Implicitselected by user
Equal Concentric Parallel
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Implicit Constraints
Closure Segment Overlap Endpoint / LineOverlap
Tangency
Parallelism Perpendicular Same Size Concentric
Coincident
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Creating Constrained Model
A: Create rough sketch
B: Define parameters and constraints on dimensions
C: Edit parameters to adjust geometry
D: Generate part using extrusion!
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Demo
• Let’s make a ‘cube’ with a hole through it!
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Setup to Sketch a Rectangle
• Select ‘Sketch’
• Select ‘Top Plane’ to draw rectangle
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Draw Rectangle
• Draw rectangle ‘roughly’ that looks like a ‘square’
• But notice that it is not a square yet
• What we need to do to make it square?
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Set ‘Equal’ Constraint on Edges
• Select lower-horizontal edge and select right-vertical edge(holding ‘Shift’ key’)
• Select ‘Equal’ from ‘Add Relations’ tools
• Notice selected items listed
• Notice “ = “ placed next to the lines selected
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Set ‘Dimension’ Constraint
• Select ‘Smart Dimension’
• Select lower horizontal edge
• A dimension will appear with a dialog box with an input field
• Drop down to see options
• Select ‘Link Value…’
• In the ‘Shared Values’ dialog box, type ‘SIZE’ in the name field; and press OK
• We created our first parameter!
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Parameter Value Changed
• Try changing the value on smart dimension; Let’s make it ‘0.05’
• What do you expect?
• Exit ‘Sketch’
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Use Parameter Defined
• Let’s use ‘SIZE’ parameter to define the height of the CUBE!
• Select ‘Sketch’ again
• Select ‘Front Plane’ from the ‘Part3’ after collapsing the tree
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Create Element to Constraint to Parameter
• Select ‘Trimetric’ view
• Select ‘Center Line’ from ‘Sketch’ toolbar
• Draw a construction line from one of the points on the square
• “CONSTRAINT” line VERTICAL
• Now, let’s define its size… or set it to ‘SIZE’ parameter
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Set Dimension Parameter
• Select ‘Smart Dimension’ one more time
• Select the ‘Center Line’ created
• Place the dimension element
• Select ‘Link Value’ while editing
• On the ‘Share Values’ dialog box, select Name pull-down menu to select “SIZE” parameter
• Voila! If you change the size of any line reading its value from “SIZE” all others will follow this change!
• Advantages?
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Create the “CUBE”
• Select “Extruded Boss/Base” command from “Features” toolbar
• Select one of the edges on the square to define the plane
• In ‘Extrude’ properties dialog:– Set ‘From’ as ‘Sketch Plane’– Set ‘Direction 1’ to ‘Up To
Vertex’– On the drawing, select the top
point on the center line (purple)
• Confirm all actions by selecting green ‘Check’ buttons!
• There you go, this is our parametric cube
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Challenge
• How can we create holes as shown in the figures?
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Equations and Link Values
Pros Cons
Equations –Easy to use–Limited set of functions
–Without good dimension names, can be difficult to set up–Can't change the driving (left-side) dimension
Link (Shared) Values
–Easy to use–Ties a single value together–Any linked valued can be changed, and the other updates
–Can provide a direct link only to another value–Hard to understand what's been linked–Limited scope
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Assignments
Reading
• Text: Chapter 4 “Modeling Fundamentals”
• Wikipedia:– Solid modeling: http://en.wikipedia.org/wiki/3D_modeling
– Constructive Solid Geometry (CSG): http://en.wikipedia.org/wiki/Constructive_solid_geometry
Pre-Lab (see next slide , and Pre-Lab document)
Reflective Blog/journal on parts modeling:
• Complete after finishing week 9 project deliverables
• 2 questions on webct
This Week’s Lab
• Step 2 of project– Create parts in SolidWorks– Sketch needed parts– Dimension them– Assign parts to group
members
• Don’t jump into SolidWorks too soon!– Spending more time preparing
and planning will save you time in the long run!
Pre-lab Assignment
• Sketch 2 parts from your AMT (nothing too simple)• Dimension• Label constraints• Label relationships
• Provide rough plan (sequence of sketches or brief description) outlining approximate steps to create parts in SolidWorks.
• See e.g. Feature-Planning Strategies (slide 31 in part 1 slides)