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

Objectives Introduce concept of design intent Use constraints in SolidWorks to match design intent

Design Intent What you intend a design to do. Some intentions can be modeled. Others not.

Modelable Design Intent I intend that the Centre of Effort align with the Centre of Lateral Resistance.

Un-modelable Design Intent I intend that a new boat design transforms the sport of sailing.

A Square? And meet at right angles What is a square? Square in SolidWorks Draw rectangle [Select one edge and define length using Smart Dimension] Select perpendicular edge, set relationship with previous edge as ‘equal’ 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

Constraint Example model for demonstrating constraints 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

Constraints in Parts Often think of constraints when creating assemblies But, constraints are just as useful when creating parts http://www.seacadtech.com/torimoto/

Types of Constraints Size Location Orientation Explicit defined by user AD = AB R = AB / 4 Center point on midpoint of diagonal Angle DAB and ABC = 90° Implicit selected by user Equal Concentric Parallel

Implicit Constraints Endpoint / Line Overlap Tangency Closure Segment Overlap Concentric Same Size Perpendicular Parallelism Coincident

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!

Demo Let’s make a ‘cube’ with a hole through it!

Setup to Sketch a Rectangle Select ‘Sketch’ Select ‘Top Plane’ to draw rectangle

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?

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

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!

Parameter Value Changed Try changing the value on smart dimension; Let’s make it ‘0.05’ What do you expect? Exit ‘Sketch’

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

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

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?

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

Challenge How can we create holes as shown in the figures?

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 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

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 Don’t jump into SolidWorks too soon! 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)