Appropriate Technology in an Introductory Engineering Design Experience

Alan W. Eberhardt,1 R. Justin Lesley1 Tina G. Oliver,2 Rose N. Scripa3

Biomedical Engineering,1 Mechanical Engineering,2 Material Science & Engineering3

University of Alabama at BirminghamBirmingham, AL

Appropriate Technology in an Introductory Engineering Design Experience

Outline

• Undergraduate Designs to Aid Disabled• NSF & NCIIA activities• SIFAT, Engineers w/o Borders &

Zambia• EGR 200 design project• Appropriate technology constraints• Engineering design tools• Assessments and Results

• student & faculty perspectives

• NSF RAPD funding • 13 years +

• Projects to aid children & adults (in Alabama) with various disabilities• Senior Design• EGR 100, 200

• BME, MSE, ME

Undergraduate Design Projects for People with Disabilities

New direction:Appropriate technologies• NCIIA funding – 2 years• Partner with EWB using appropriate technologies• Senior design projects for disabled in developing

countries• Peru – all terrain crutch• Zambia – bamboo wheelchair

UAB Engineers w/o Borders + SIFAT (Servants in Faith and Technology)

• SIFAT: Christian nonprofit that provides training in self-help programs for a needy world.

• EWB + SIFAT building a training facility in Zambia

• Opportunity for reproduction of devices designed by UAB students

EGR 200 Intro to Engineering

• Course is for 2nd year transfer students (pre-BME, -ME, -CE etc)

• Majority from 2-year community colleges

• 2 sections of ~50 students• Topics: Reverse engineering, team

projects, oral & written communication

+5 week design project

Design Project:Crutches using appropriate technology

Crutches for men, women and children of Zambia

Zambia• One of the poorest countries

in the world

• 87% of total population live on less than $2 USD per day

• Health problems abound…

Ex. Infection leads to amputation… war torn neighbors

Design Constraints

• Appropriate materials• Bamboo poles, string, glue, leather,

cloth scraps, burlap• Appropriate technology

• Hand tools only (saws, files, vises, hand drill)

• No power tools or expensive machining equipment

• Time: 5 weeks (end of term)

Schedule – Fall 2010

Class Date Activity

1 10/29 Introduction to problem

2 11/5 Lab Safety, SOE Design Lab visit, Brainstorm designs 3 11/12 Project work* – materials list due by end of class4 11/19 Project work* - continued

X 11/26 Thanksgiving holiday

5 12/3 Project work*, stress analysis

6 12/10 Oral presentations/reports & completed crutches due

* class time to work in teamsSOE Design Lab/computer labs

Design Contest

• Crutch designs judged for “Best Engineered Device” based on Final Presentation + Final Report

Winning team gets dinner at Dreamland Bar-B-Q

• “Best engineered” based on use of engineering tools in design• Computer aided drawing• Free body diagrams, force/moment calcs• Stress and buckling analysis• Material description – engineering properties

Drawing

• Discuss the range from hand sketching to Pro-E CAD• Intro to Pro-E demo, some students taking Pro-E

course

Statics, Equilibrium & FBD’s

SF = 0

Action-reaction (Newton’s 3rd)

SM = 0

Ex. Civil War era crutch

1. Underarm piece

P

P

P

M

Mechanics of Solidsaka, Stress and Strain• Fundamental concepts of stress and strain can be

illustrated by considering a “prismatic bar” (straight structural member with constant cross section) that is loaded by axial forces P at the ends

• Material failure is often a function of stress or strain (not just the force applied)

Stress - strain curve:Engineering materials

In elastic zone, s = Ee

“Hooke’s Law”

Material selection/analysis

• CES Edupak software

• On EGR computers:• Programs

• Engineering software• CES

• Properties of bamboo• Modulus• Failure strength• Joining techniques

Column Buckling

• Pcrit = p2 EI/Le2

Note: The effective length Le depends on the boundary conditions

Important!Allocated class time for project work• SOE Design Lab• Tables for teams

with materials (bamboo, string, glue, etc)

• Hand saws/drills, files…

• Instructor + grad student (Lesley) circulating & advising…

Rubric circulatedLevel 5 Level 3 Level 1

Background

Background review is thorough and provides sufficient information regarding the need for design, Engineers w/o

Borders, potential benefactors, etc.

Background review is somewhat lacking and

does not provide sufficient information regarding the

need for design, Engineers w/o Borders,

potential benefactors, etc.

No background review is provided.

Problem Statement &

Design Constraints

Problem statement concise and based on background review.

Design constraints are complete.

Problem statement neither concise nor based

on background review. DC’s incomplete

No problem statement provided.

Drawings

Excellent drawings that involve use of computer

aided design (CAD) software and include labels & dimensions

Fair drawings that involve use of traditional drafting tools with some labels &

dimensions

No drawings included

Free body diagrams

Excellent free body diagrams with correct

calculations of forces and moments in crutch sub-

structures

Some free body diagrams with attempted

calculations of forces and moments in crutch sub-

structures

No FBDs

Calculations

Stress and buckling calculations completed

correctly for crutch sub-structures

Stress and buckling calculations attempted for

some crutch sub-structures

No calculations included

Material descriptions

Bamboo/sisal fiber/wood glue material

descriptions included with comparison to

calculated stresses to ensure safe design

Material descriptions included without

comparison to calculated stresses to ensure safe

design

No material descriptions

Presentation (slides,

mechanics, etc)

Outstanding Pretty Good Lousy

Paper (grammar,

headings, etc)

Outstanding Pretty Good Lousy

Students told how they would be graded

= how judged for contest….

Results & student learning outcomes:

• All design teams completed their projects (19)

• Student ownership & satisfaction was remarkable (personal best for freshman experience)

• Students comments: “understand what it means to design … what engineers do… feel prepared & excited for next level courses…”

• Many signed up for UAB Engineers w/o Borders

Benefits from the teaching end

• Costs are low• $500 covered two sections of ~50

students• Materials purchased a priori &

provided• Bamboo, string, glue, leather, burlap

• Facilities are simple• Hand tools (saws, files, hand drills,

vises) • Projects are safe

• No special training needed…

Acknowledgments

• National Science Foundation (NSF RAPD)

• National Collegiate Inventors and Innovators Alliance (NCIIA)

• UAB School of Engineering• Dreamland BBQ

Thank you!