P14042: Una -Crutch

P14042: UNA-CRUTCHRight Move, Right Place, Right Time

Systems Design Review Day 2Ana AllenJoanna Dzionara-NorsenBeverly LirianoDan Sawicki

Agenda

Background

• Problem Statement Summary• Customer Requirements• Engineering Requirements• HOQ• Market Analysis/ Benchmarking• Functional Analysis

Concept and Architecture Development

• Risk Assessment • Test Plan

Engineering Analysis

CONCEPT AND ARCHITECTURE DEVELOPMENT

Concepts

Initial Concepts Rev 1Pugh Chart

Initial Concepts Rev 1 Pugh Chart (Continued)

Continued

Initial Concepts Rev 2Pugh Chart

Initial Concepts Rev 2 Pugh Chart (Continued)

Continued

New Concepts Rev 3Pugh Chart

Connective Mechanism Terms

Male/ Female Connection Pin Magnetic

Rubber Snap Guide Track

Clamp Tupperware Snap

Concept NA• Pros:

• Springs relax user tension• Large surface area on single

crutch• Hinge is simple to use

• Cons:• Expensive• Many components• Too many steps to assemble

Hinge

Pin

Concept NB

• Pros:• Easy connection• Aesthetically pleasing• Innovative design• Minimal components• Spring base

• Cons:• Bulky• Potentially expensive• Magnetic Connection

Male/female mold

Male/female mold and/or pin

Magnetic

Concept NC

• Pros:• Adjustable handle• Spring base• Male/female mold is an easy

connection• Innovative design

• Cons:• Stability• Thickness

Male/female mold

Male/female mold

Clamp

Concept ND

• Pros:• Lightweight• Revolutionary handle design

• Cons:• Base connection is

inconvenient if user is on one leg

• Similar to axilla crutch

Snap

Male/female mold

Guide track

Concept NE• Pros:

• Foldable into a cane• Lightweight• Stable

• Cons:• Two separate bases• Not aesthetically pleasing• Pad is in contact with the

ground

Pin

Male/female mold

Concept NF

• Pros:• Largest surface area for

connection• No axillary component• Spring base• Minimal components

• Cons:• Not aesthetically pleasing• Stability compromised

Male/female moldfor elbows

New Concepts Rev 4Pugh Chart

System Architecture

ENGINEERING ANALYSIS

Engineering Analysis Overview

Friction Analysis

Cantilevered Beam Analysis

Static Analysis

Loads: Statics Analysis of Axilla Crutch

30.000 0.524 0.866 0.500 75.000 -129.904 150.000 129.904 75.000

θ[deg] θ[rad] cos(θ) [deg] sin(θ) [deg] Px Py P N Ff[deg] [rad] [deg] [deg] [lbf] [lbf] [lbf] [lbf] [lbf]

High μs

value to

low μs

value

Ice will result in slip the quickest!

Concrete is least likely to

slip!

Cantilevered Beam Analysis• Crutch handle modeled as a cantilevered beam with a

distributed load and external moment:

• Cross-sections considered: circular, square, hollow circular, I-beam, T-beam

• Maximum stress from bending:

L = 0.39in

L = 0.39in = 10 mm

OD = 0.47 in = 12 mm

Smallest dimensions at which the maximum stress from bending does not exceed the yield strength of aluminum

= 25 MPa = 27.6 MPa

Nf

P

ΣFy=ma=0Σfy=-P+Nf=0

P=Nf

Static AnalysisASSUMPTIONS:

Static Analysis

Nf

Dx

Cx

Cy

DyΣFy=ma=0

ΣFy=Nf-Cy=0Nf=Cy=P

ASSUMPTIONS:

Static Analysis

P

ByBy

BX BX

ΣFy=ma=0ΣFy=2By-P=0

By=P/2

Statics Analysis

Ax Ax

Static Analysis

Bx

Cx

Dx

Ax

Cy

Dy

By

unknown: 3 unknownsAx,BX,Cx

Equations: 3 equationsΣFy=ma=0ΣFx=ma=0

ΣM=0

ASSUMPTIONS:

Prototype Test Plan

Risk Assessment

Action Items for Subsystem Design Phase

Week 7

Nazareth Orthopedic Clinic

Continue Mechanical Analysis

Continue Concept Design

THANK YOU AND WE ARE NOW OPEN FOR QUESTIONS!

BACKUP SLIDE

Detailed Project Plan (Week 7)

Detailed Project Plan (Week 8-9)

Bill of Materials

Final Product Test Plan

QUESTIONS?