5: CAD Design Principles for Electric Vehicles

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Questions and Answers

What major function does the drivetrain serve in the model?

It supports the vehicle's bodywork.

It regulates the steering system.

It houses the electronics.

It connects the electric motor to the wheels. (correct)

Which of the following parts is NOT indicated in the motor shaft assembly?

Differential drive

Coupling motor - shaft

Gears

Suspension (correct)

In the modeling operations mentioned, which sequence is least effective for creating complex part features?

Extrudes only

Extrudes and then adds features

Combination of both methods

Revolve only (correct)

What is the primary goal of 'Design-by-Features' in engineering geometry?

To first define the basic shape and then add features. Signup and view all the answers

Which of the following components is responsible for transmitting power from the motor to the wheels?

Drive shaft Signup and view all the answers

In terms of engineering design, how are features typically added after defining the shape?

By applying design rules and constraints. Signup and view all the answers

Which of the following is a learning objective stated for the engineering design course?

Understanding what part families are and their applications Signup and view all the answers

What is one of the basic feature types students will learn about in CAD systems?

Extrusions Signup and view all the answers

What is the focus of the course in the Engineering Design + Computing Laboratory?

Parametric modeling and efficient design processes Signup and view all the answers

Which alteration in CAD modeling steps could produce the object displayed in the bottom view?

Changing the sequence in which steps are applied Signup and view all the answers

What impact does changing the parameters of a modeling step have on the final object?

It may alter the size or shape of the feature Signup and view all the answers

If the 'hole' step is executed before the 'shell' step, what is likely the result?

The model may not retain the original shape Signup and view all the answers

What process can help in visualizing the effect of each modeling step in CAD?

Using a feature tree to trace modifications Signup and view all the answers

What is the primary reason for using a 'pattern' step in CAD modeling?

To replicate features efficiently Signup and view all the answers

When would it be most beneficial to replace a modeling step in CAD?

When the current step does not fit the overall design intent Signup and view all the answers

What could be a consequence of applying features in the incorrect order?

The model might lose its operational functionality Signup and view all the answers

Why is it important to understand the interaction of modeling steps in CAD?

To ensure the design meets all technical requirements Signup and view all the answers

What is a characteristic of profile tolerance in assembly features?

The actual surface must be within a tolerance zone. Signup and view all the answers

What does a co-axial assembly feature involve?

Components aligned along a central axis. Signup and view all the answers

Which shape is used to describe the termination of an extrusion as shown in the feature verification process?

Round Signup and view all the answers

Which statement best describes overlapping fillet and round features?

They represent different methods of terminating edges. Signup and view all the answers

What is meant by 'model history' in design verification?

The sequence of actions undertaken during the design process. Signup and view all the answers

What role does a sketch play in the extrusion model history?

It outlines the initial shape before extrusion. Signup and view all the answers

What is the purpose of edge blending in model history?

To transition between adjoining surfaces smoothly. Signup and view all the answers

What does the term 'termination' refer to in feature verification?

The end point of an extruded feature. Signup and view all the answers

What is the first step in creating a parametric model?

Define Rough Geometry and Parameters Signup and view all the answers

Which action is performed to modify an existing parametric model?

Removing a geometric constraint Signup and view all the answers

What would happen if the relation p0 = 90mm is replaced with p0 = p1 + 10mm?

The system would solve the constraints and update the model Signup and view all the answers

What does a parametric relation typically define in a model?

Linkages between geometric entities Signup and view all the answers

Which of the following is NOT a typical operation when handling constraints in parametric modeling?

Define Material Properties Signup and view all the answers

What is indicated by the relation R = b/2 in parametric modeling?

R is dependent on the value of b Signup and view all the answers

What is the purpose of geometric constraints in a parametric model?

To define relationships between geometric entities Signup and view all the answers

Study Notes

Learning Objectives

Students will learn to think about design parametrically in CAD systems.
Students will understand the concept of a feature, basic feature types and their properties.
Students will understand what part families are and how they are used.
Students will be introduced to Additive Manufacturing (3D Printing).

CAD Model of the PLUS II

PLUS II is an electric vehicle
Made of several components including chassis, bodywork, windshield, electronics, door, steering system, front wheels, drivetrain, back wheels
Example of CAD model used to design these components

Drivetrain

Example component of PLUS II
Composed of electric motor, wheel, suspension

Example part from Kyburz: Motor Shaft

Motor shaft is an example of design using CAD features
The motor shaft is broken into various parts with different function and material properties
Parts are indicated by different colours eg, orange - bearings, green-sealings, blue-drive shaft, pink-coupling motor, red-differential drive, grey-gears, transmission
Drivetrain is a key component of electric vehicles.

Question: Modeling operations

The question asks about the best way to represent the basic shape of a part in CAD, using geometric modelling operations
The options are either 1. Extrusions only, or 2. Revolves only

How can we encode the engineering meaning of geometry?

CAD features can be used to encode engineering meaning of geometry
This is referred to as "Design-by-Features"
This makes designing easier to understand, manage and modify
Example of this is in the design of a gear
A gear is a complex shape, with many features such as key seat, chamfer, centre hole, locking pattern, groove
Features are built up on top of basic geometry to create complex shapes
Example of features: chamfer, round, mirror geometry

Assembly and Tolerance Features

Assembly features allow parts to be assembled and constrained in CAD software
Example of assembly feature - co-axial assembly features, where parts are aligned and attached to each other
Tolerance features are used to control dimensional accuracy of parts
Tolerance features ensure that a part is within specified limits
Example - profile tolerance feature

Feature Verification

Feature verification is important to ensure CAD features work as intended
Features can sometimes interact with each other, creating unexpected geometry
Example - fillet and round feature, where the round overwrites the fillet
Model History can show how a model was created
History can show a breakdown of the features used to create the model

History Dependency and Interaction

CAD models have 'history' meaning they remember how they were created
History can be used to modify a model easily
Changes to a model can have cascading effects on other features
Example: modifying a hole feature can affect a pattern or shell

Question: Alternative Model

This question asks about modifying a sequence of modelling steps in CAD
Modifying the sequence of steps can change the outcome of a design
Example - switching the order of 'shell' and 'hole' operations can create a different result

Sketch and Parametric Modeling Overview

Parametric modeling allows for flexible and dynamic design
Parametric modelling uses constraints and parameters to define geometry
The relationships and constraints define how geometry should behave
The model automatically updates when parameters change
Example: changing the length of a line can affect the position of other geometric entities

Question: Parametric Modeling

This question asks about how a parametric model responds to changing its parameters
Changing parameters can change the model because of defined relationships
The constraint solver will find the new solution and update the model accordingly

How to Create a Parametric Model

Parametric models are created by linking geometric entities using parameters and constraints.
Constraints define relationships between different geometric entities in a CAD model.
Example constraints include:
- Lines parallel to lines
- Lines perpendicular to lines
- Circles tangential to lines or other circles
- Points constrained to a specific location.
Parameters are used to define specific values for the constraints.
Example parameters include:
- Angles
- Lengths
- Radii.

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Description

This quiz explores design parametrics in CAD systems and key features related to the PLUS II electric vehicle model. Students will learn about part families, additive manufacturing, and the specific components involved in the vehicle's drivetrain. Test your understanding of CAD concepts and their application in designing modern electric vehicles.