Systems Design Review - Edge

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26 Νοε 2013 (πριν από 3 χρόνια και 11 μήνες)

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P14042:
UNA
-
CRUTCH

Right Move, Right Place, Right Time


Systems Design Review Day 2

Ana Allen

Joanna
Dzionara
-
Norsen

Beverly
Liriano

Dan
Sawicki


Agenda

Background


Problem Statement Summary


Customer Requirements


Engineering Requirements


HOQ


Market
Analysis/
Benchmarking


Functional Analysis

Concept and Architecture Development

Engineering Analysis


Risk Assessment


Test Plan

Tuesday

Thursday

CONCEPT AND
ARCHITECTURE
DEVELOPMENT

Concepts

Initial Concepts Rev 1

Pugh Chart

Initial Concepts Rev 1

Pugh Chart
(Continued)

Initial Concepts Rev 2

Pugh Chart

Initial Concepts Rev 2

Pugh Chart
(Continued)

New Concepts Rev 3

Pugh 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:


T
wo 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 mold

for elbows

New Concepts Rev 4

Pugh Chart

System Architecture

ENGINEERING ANALYSIS

Engineering Analysis Overview

Friction Analysis

Cantilevered Beam Analysis

Static

Analysis

Loads: Statics Analysis of Axilla Crutch

Analyzed from user recommended
angles between 0
°

and 45
°
.

Three Forces acting on object.

Friction Force Increases as
θ

increases.

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
μ
s
value
to
low
μ
s
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

σ
𝑐𝑖𝑐
,



= 25
MPa

σ
𝐴𝑙

= 27.6
MPa

N
f

P

Σ
Fy
=ma=0

Σ
fy
=
-
P+Nf
=0

P=
Nf


Static Analysis

Negligible out of plane
loads

Entire user load is on the
hand grip

The underarm pad is being
held by a screw.

ASSUMPTIONS:

Static Analysis

N
f

D
x

C
x

C
y

D
y

Σ
F
y
=ma=0

Σ
Fy
=
Nf
-
Cy=0

Nf
=Cy=P

Force on
Dy

can be
neglected

Force
Dx

has a direct relation
with
Cx

being
Dx
=
Cx
/2

ASSUMPTIONS:

Static Analysis

P


By

B
y


B
X

B
X

Σ
F
y
=ma=0

Σ
F
y
=2By
-
P=0

By=P/2

Statics Analysis

A
x

A
x

Static Analysis

B
x

C
x

D
x

A
x

C
y

D
y

B
y

unknown: 3 unknowns

Ax,BX,Cx

Equations: 3 equations

ΣFy
=ma=0

ΣFx
=ma=0

ΣM=0

Force on
Dy

can be
neglected

ASSUMPTIONS:

Prototype Test Plan

Risk Assessment

Action Items for Subsystem Design Phase

Week 7

Nazareth
Orthopedic
Clinic

Continue
Mechanical
Analysis

Continue
Concept
Design

Week 8

Connective
Mechanism
Prototypes

User
Interface
Prototypes

Experimental
Friction
Analysis

Week 9

CAD Design

FEA Analysis
of Prototype

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?