Evaluating Your Design

How to determine if you got it right

IDENT

OPP

DEFINE PROBLEM

GEN

CONCEPTS

GATHER

INFO IMPLEMENT

SCREEN

CONCEPTS HANDOFF

ME 4054 Design Projects

1. Sit with your team 2. Team takes 10 index cards

before lecture starts

37

Take-Home Message

A good design is one where test results

prove that it meets the requirements

$30 for students, register at the door www.dmd.umn.edu

Exercises

• As a team, you will be completing exercises

• For each

– Work as a team

– Write your final response on an index card

– You may be giving the card to another team for assessment

Why Prototype in ME 4054?

A. To conduct engineering tests

B. To communicate with the customer

C. To have something to show at the Design Show

D. To reduce technical risk

As a team, write answer on index card. You may select one or more of the

choices

As a team, write answer on index card. You may select one or more of the

choices

ALL KINDS OF PROTOTYPES

• Anything and everything can be called a prototype

– Sketch

– Carved foam

– Creo rendering

– ANSYS simulation

– Bread board

– Double (or half) scale

– PowerPoint UI

– Functional/non-functional

– Engineering model

– Display model

Comprehensive

Analytical

Physical

Focused

Virtual Prototyping

IDENT OPP

DEFINE PROBLEM

GEN CONCEPTS GATHER INFO IMPLEMENT SCREEN

CONCEPTS HANDOFF

Evaluation in the Design Process

Return to the design requirements

Product Design Specification

Planning the Prototype

• Learning needs (engineering)

• Communication needs (boss, customer)

Define Purpose

• Works-like/Looks-like

• Physical/Virtual

Establish Level

• Evaluate by testing Create Test

Plan

• Design

• Fabricate

• Evaluate

Create Schedule

Exercise

For your next (or current) prototype, describe three engineering performance features you plan to test

Key Dates For Prototype

1 •Ready to assemble •Ready to assemble

2 •Ready to test •Ready to test

3 •Test results complete •Test results complete

Exercise

For your next (or current) prototype, list 3 dates:

1.Ready to assemble 2.Ready to test 3.Test results delivered

Product Product Prototype Prototype

Examples from draft design report

1. Objective

2. Method

3. Data Analysis

Every metric in the list of design requirements, must have a

related test plan

Exercise

Write a test plan to evaluate, using your prototype, one engineering requirement of your design

1. Objective 2. Methods 3. Data Analysis

Physical Test

Engineering

•Output

• Strength

•Cyclic fatigue

•Acceleration response

•Weight

• Size

Use

•Time of procedure

• Fit

• Instructions

Simulation Test

FEM

• Stress

•Deflection

•Temperature

• Flow

Dynamics

• Step response

• Frequency response

•Natural frequency

Kinematics

•Motion

• Interference

Example: Simulation of Manufacturing Line

Simulation of one station

Build Test Apparatus and Evaluate

Additional Methods for Evaluation

• Sensitivity Analysis: how sensitive is your design if a key parameter is not closely specified?

• Design of Experiments: Finding an optimum set of processing conditions (see book by George Box, Design and Analysis of Experiments)

• Statistical Process Control: In a manufacturing process what is the range of variability that can be expected? (D&M I manufacturing text has overview)

• Measurement Error Analysis (Measurements lab)

How to get an A if you have a physical prototype