1.2.5 Parametric Modeling DeMember PDF

1.2.5 Parametric Modeling DeMember Parameter: Measurable factors that define a system. Presentation Overview Types of computer design parameters Review of geometric constraints Parametric constraints Creation of parametric equations that maintain geometric proportions Parameters 3D CAD pro...

1.2.5 Parametric Modeling DeMember Parameter: Measurable factors that define a system. Presentation Overview Types of computer design parameters Review of geometric constraints Parametric constraints Creation of parametric equations that maintain geometric proportions Parameters 3D CAD programs use parameters to define a model of a design solution. A parameter is a property of a system whose value determines how the system will behave. Types of Parameters 3D CAD programs typically have three types of user-defined parameters: ○ Geometric Constraints (review) This is what we have done all year so far. Example 2.5 in X 1.5 in X 0.25 in keychain design made things a geometric constraint. ○ Parametric Constraints - Uses formulas and ratios, not exact measurements. Ex. 3D printing at 50%. ○ Assembly Constraints (discussed later) Review of Geometric Constraints Geometric relationships that the user assigns to sketched elements. Usually these are non-numeric but you can add a measurement to them. Examples ○ Making two lines parallel ○ Making two arcs concentric ○ Making a line horizontal Review of Geometric Constraints Coincident Collinear Concentric Fix Perpendicular Horizontal Parallel Vertical Tangent Smooth Symmetric Equal Parametric Equations Scenario: A child’s proportions are similar to those of an adult A chair could be dimensioned so that changing the seat height uniformly scales all other chair features Discuss with your partner: What are five most important measurements you need to make this chair? Parametric Constraints Are used to control the size and location of geometry. Often used to set a limit. May take the form of simple numeric values such as 2 inches or 25 degrees. We have done this!!! May take the form of abstract algebraic formulas such as (d2*d0)/d5 or in Onshape (#lengthX#depth/2) Symbols: + – * / add subtract multiply divide  Parametric Equations Each dimension is given a designation or variable name. Starts with d0. d means dimension. In Onshape it will display f. x # is used for formulas. Example #overallwidth. No spaces. Use the Variable Table (right side, middle) or Variable command (x) Parametric Equations OnShape  1.2.5 Assignment Parametric Modeling Day 1 Blocks Create a new Doc called Parametric Day 1 [last STEP 1 Three Constrained Parts. name] and move it to your IED Folder. "WEDGE" --> base, height, depth STEP 1: Create each of these shapes (3 different Parts) and constrain them to the ratios below. height = 4 * base depth = 2 * base "CYLINDER" --> diameter, height height = 3.75 * diameter "TALL BLOCK" --> width, height, depth height = 7 * width depth = 2.75 * width STEP 2 Create a unique shape that uses arcs, offset and mirror. Use constraints for any 3 variables. You decide.  1.2.5 Assignment Parametric Modeling Day 2 Cube DIRECTIONS: Follow the directions on the Google doc to complete the cube. Make a copy of the public Onshape document linked on the assignment. Before submitting this assignment, be sure to test out your variables by changing their values and checking to see if the design of the cube stays intact. Once you have tested the cube, submit your website url in Canvas. Parametric Equations Algebraic equations that use variables can be substituted for individual numeric values fx d7 = ((d2*d0)/d5) + 2 in. The resulting dimensional value may change, but the formula will remain constant Symbols: + – * / add subtract multiply divide Parametric Equations Extrusion and taper angle values are also given designations. Parametric Equations Problem ○ The Overall Plate Depth (d0) and the Overall Plate Width (d1) must maintain a constant ratio. ○ If the plate were scaled up or down, the overall dimensions would remain proportional to each other. Parametric Equations If the Overall Plate Depth and Overall Plate Width must maintain a constant ratio, then the current dimensional values can be used to establish the ratio. 5 in. Parametric Equations If the Overall Plate Depth and Overall Plate Width must maintain a constant ratio, then the current dimensional values can be used to establish the ratio. 5 in. 5 : 3 or 5/3 or 1.66667 Note: unitless values 3 : 5 or 3/5 or.6 Parametric Equations If dimension d0 is the only linear dimension that will have a numeric value, then it must be used to develop an equation that will maintain proportionality. 5 in. d1 = d0 in.*(5/3) or d1 = d0 in./(3/5) 5 in. = 3 in. x 1.66667 5 in. = 3 in. ÷.6 Parametric Constraints Can be tied to spreadsheets that allow for more complex mathematical formulas Parametric Equations Both equations work, so either may be used in the CAD program as a parametric equation for dimension d1 to maintain proportionality. 5 in. d1 = d0 in.*(5/3) or d1 = d0 in./(3/5) 5 in. = 3 in. x 1.66667 5 in. = 3 in. ÷.6 Parametric Equations Each parametric equation must tie back directly (e.g., d0/2) or indirectly (e.g., d1*0.8 = (d0*(5/3))*0.8) to a dimension that has a true value. In this case dimension d0 has a true value of 3 in. Understanding Parametrics 11 min. Parametric Equations in Inventor Dimension parameters are named in sequential order beginning with d0. The first dimension you place will be labeled d0, the next d1, and so on. Parametric Equations in Inventor® You may type equations into the dimension dialog box (instead of a number). Parametric Equations in Inventor® You may assign the parameter name to any dimension. Parametric Equations in ® Inventor You may change the display mode of dimensions by right-clicking. Choose “Name” as the dimension display in order to display the parameter names instead of the numeric value. Parametric Equations in ® Inventor The parameter table displays parameter names, units, equations, and numeric values of dimensions. Access to the parameter table is provided under the Manage tab. Parametric Equations in Inventor® You may revise parameter names and equations and add comments within the parameter table The dimensions will automatically update when you click Done. 1.2.5 Parametric Modeling Part 1 (Blocks) DIRECTIONS: Create a new Onshape document named "1.2.5 Parametric Modeling" in your shared/named folder. Then model the three parts shown in the same Onshape file, but in 3 separate part studio tabs. Each part will be modeled using parametric dimensions. You can set the variable values to anything you like for each part, try to use formulas reliant on the first measurement. FOR EXAMPLE. "WEDGE" --> length, height, depth Length = 2, Height = 'Length'*2, depth=length/2 "WEDGE" --> length, height, depth "CYLINDER" --> diameter, height "TALL BLOCK" --> length, height, depth 1.2.5 Parametric Modeling Day 2 (Cube) DIRECTIONS: Follow the directions on the Google doc to complete the cube. Before submitting this assignment, be sure to test out your variables by changing their values and checking to see if the design of the cube stays intact. Once you have tested the cube, submit your website url in Canvas. Potential Project Define the Project: Develop a comprehensive project related to parametric modeling, such as designing a prototype of a product or creating a complex model that solves a real-world problem. Clearly outline the goals, expectations, and assessment criteria for the project. Assign Differentiated Roles: Divide students into groups and assign each student a role based on their strengths, interests, and skill levels. For example: Researcher: Responsible for gathering information and resources about parametric modeling and related vocabulary. Designer: Focuses on creating the initial design and ensuring it meets project specifications. Modeler: Uses the parametric modeling software to build and refine the model. Presenter: Prepares and delivers the final presentation, explaining the project’s objectives, process, and outcomes.