Lecture Autodesk inventor Parametric modeling An introduction

Parametric Modeling
An Introduction


Parametric Modeling
Also called:
Feature-based modeling
Constraint-based modeling

Parametric Modeling uses parametric
constraints to define and easily modify
part features, and to create relationships
between these features in order to create
intelligent part models. These virtual parts
can then be combined to form assembly
models.


Features
Basic unit of a parametric solid model
A feature is a 3D shape. Parts are
formed by their features
Model features mimic actual design &
manufacturing features (e.g., fillet,
counterbore hole, draft angle)
2 basic kinds of model features:



Sketched (e.g., extrusion, revolution, loft)
Built-in (e.g., hole, chamfer, fillet, shell)

 No sketch required


Parameters
A parameter is a named quantity whose
value can be changed


For example, d0 = 10

Parametric dimensions:





Control feature size
Are easily modified  feature geometry
changes
Establish relationships across features,
parts, assemblies
 For example, d0 = d1/2


Constraints
A constraint is a mathematical
requirement placed on the geometry of
a 3D model
Kinds of part constraints:




Dimensional – limits feature size
Geometric – limits feature shape (e.g.,
parallelism tangency, colinearity)

Assembly constraints (e.g. mate, insert)


Parametric Modeling Characteristics
Model flexibility; easy to update, modify
Reflects design intent (i.e., the purpose or
function of a feature)
Model history viewable in feature tree (similar
to CSG)
Drawings generated from parametric model
are linked to model  associative
Relationships between parts are maintained in
database  assembly modeling


Top–Down: Product Development
Product


Assembly
Sub-assembly
 Part


Feature


Bottom-up: Part Modeling
1. Define sketch plane
2. Sketch the geometry


1.
2.
3.
4.

Some geometric constraints added automatically

Add other geometric constraints
Add dimensions  fully constrained
Create the (base) feature
Repeat 1 to 5, adding other (sketched and/or
built-in) features


Sketch
Rough sketch


Some geometric
constraints are
automatically applied

Geometric Constraints
Can display
constraints

Apply
additional
constraints


Dimensional Constraints
Add Dimensions


Profile is fully constrained


Feature Generation - Extrude


Built-in Features


Feature Tree


Parametric Modeling
An Introduction

Nada Mas