Multidisciplinary Engineering Senior Design

Project 6218 Soft Tissue “Tensile” Tester Preliminary Design Review

2/24/2006

Project Sponsor: Bausch & Lomb

Team Members:Ryan Schkoda – Team Lead

Christopher Kudla – Lead engineerKristina Schober – Mechanical Engineer

Robert Mc Coy – Electrical Engineer

Team Mentor: Dr. Elizabeth DeBartolo

Kate Gleason College of EngineeringRochester Institute of Technology

Agenda

• Introduction• Theory Overview• Objectives and Specifications• Concept Development• Feasibility• Component Selection & Design• Component & Assembly Test• Plan for Senior Design II

Introduction

• Little is known about material properties of the inner eye.

• Bausch & Lomb requested tensile testing device.

• A less traditional method of gathering material property information as been employed.

Membrane Theory

R

a

R

P

EhR

1 6

9

1 3 3 4 1 3/ / /•Small Deflection Equation

•Where a=span radius, R=indenter radius, h=film thickness

E

KxF

Hooke’s Law

Objectives & Specifications

•Compact and easily transportable design.

•Incorporate ergonomics.

•Overall weight < 25 lbs.

•Carrying case.

•Compliant with FDA, GMP, and OR regulations.

•Easy to operate user interface.

•Sterilization using autoclave.

•Load cell and encoder capable of continuous data acquisition.

•Repeatable mounting of specimens.

•Repeatable method of generating a sample out of the original rhexis.

•Powered by 110V outlet.

•Ability to test a sample that is submerged in a saline solution.

•Cost to be on the order of $5,000.

Concept 1- Traditional Tensile Tester

• Baseline Design• Advantages:

Familiar type of testing

• Disadvantages: Grips to accommodate sample size

Concept 2- Automated Membrane Press

• Stepper Motor driving a screw.

• Probe will be forced through material.

• Uses different method to clamp material.

Concept 3- Manual Membrane Press

• Similar to Concept 2• Less Expensive• Manual crank

provides more error.

Concept 4 – Automated Membrane Press with Servo

Motor

• Servo Motor with linear stage

• Advantages: Precise operation

• Disadvantages: Need tight tolerances

Feasibility Assessment

• Introduction– Decision making activity– Attributes

• Evaluation of Design Concepts• Pugh Evaluation

– “paired comparison”– Reference concept– Eliminate weak concepts

• Weighted Concept Evaluation– Modified Version – Group Discussion

Load Cell Selection

• Needs– Load capacity of 10g– Low “repeatability”

• Evaluation– Used 2 methods:

• Small deflection equation• Test experiment

– Noise range

• Transducer Techniques- GSO Series

http://www.transducertechniques.com/GSO-load-cell.cfm

Probe Tip Selection

• Needs– 1.5mm spherical tip– Thermal properties

strong enough to be autoclaved

• Evaluation– CMM tips (a.k.a. styli)– Ruby spherical tip

• Renishaw

0.1 micron resolution

25mm travel

DC servo motor

Linear encoder

Motorized Linear Translating Stage

Controller

• Ensures the speed and position of Linear Stage and Servomotor.

• Single axis Control• Plug and Play Compatibility• Power Amplifier• Compatible with LabView

– Drivers– DLL file for Windows

Signal Conditioning and Data Acquisition

• Signal Conditioner– Includes power amplifier for load cell– Increase measurement resolution– Improve signal-to-noise ratios

• Data Acquisition– Outputs data to user interface– Contains an analog to digital

converter– USB capable– LabView® compatible

LabView® VI Example

Control and Display

• LabView® interface• USB port link for data input• End user definable• DLL files • LabView® drivers

Load Cell

Signal Conditioner/

Amplifier

USB Data Acquisition /

A/D Converter

Motorized Linear Stage/Encoder

Motion Controller/Driver

LabView

Final Design Exploded View

Overall Design

Membrane Clamp

O-Ring GrooveMembrane Clamp

Estimated B.O.M.

Component Manufacturer Part # Quantity Cost Per Item Total Cost

Translating Stage Newport Corporation MFA-CC 1 $1,495.00 $1,495.00(949)-863-3144

sales@newport.com

Controller Newport Corporation ESP100 1 $1,325.00 $1,325.00(949)-863-3144

sales@newport.com

Sample Mount Bausch and Lomb 1 $350.00 $350.00Machine Shop

Spherical Probe Renishaw A-5000-7802 2 $22.00 $44.001-847-286-9953www.renishaw.com

Extension Spring Century Spring 80062 3 $7.50 $22.50www.centuryspring.com

Load Cell Transducer Techniques GSO-10-T 1 $625.00 $625.00(800) 344-3965tti@ttloadcells.com

Signal Conditioner Transducer Techniques TM0-1 1 $277.00 $277.00(800) 344-3965tti@ttloadcells.com

Data acquisition Hytek Automation iUSBDAQ - U120816 1 $79.00 $79.00

Material/Machining Bausch and Lomb 1 $2,000.00 $2,000.00Machine Shop

total: $6,217.50

Calibrating and Verifying Load Cell

Measuring Machined Parts

Component Test Analysis

Plan for Senior Design II

• Build Device• Develop Strategy For Interpretation• Troubleshoot• Gage R&R• Further Research of Membrane

Deflection and Simulation

Comments and Questions

Extra Slides - Krissy

Base & Load Arm

Base• Needs

– Stable support linear stage– Cone shaped feature for

water cell and sample mount.

Base & Load Arm

Load Arm• Needs

– Stable to support and align load cell

• Evaluation– Components will be

machined out of stainless steel.

– For ease of machining the base and arm will each have two separate pieces

Detailed Methods: Load Cell Selection

R

a

R

P

EhR

1 6

9

1 3 3 4 1 3/ / /•Small Deflection Equation

•Where a=span radius, R=indenter radius, h=film thickness

•Noise Range%

m ax .repea tab ility

capacity1 0 0

0 0 5

1 0 01 0 0 0 0 5

.* .g g

Concept 1- Preliminary B.O.M

Component Estimated CostMotor $360Power Screws $120Gears $175Grips $400Load Cell $505Signal Conditioner $150Data acquisition $100Controller $1,500Material/Machining $400Total $3,710

Concept 1- Traditional Tensile TesterBill of Materials

Concept 2 – Preliminary B.O.M

Component Estimated CostStepper Motor $450.00Power Screw $60Gear $75Sample Mount $350Load Cell $505Signal Conditioner $150Data acquisition $100Controller $1,500Material/Machining $400Total $3,590.00

Concept 2- Automated Membrane PressPreliminary Bill of Materials

Concept 3 – Preliminary B.O.M.

Component Estimated CostPower Screw $60Gear $75Sample Mount $350Load Cell $505Signal Conditioner $150Data acquisition $100Material/Machining $650Total $1,890

Concept 3- Manual Membrane PressPreliminary Bill of Materials

Load Cell Test

• Follow a “Transducer Checkout Guide” that they provide.

• Use a set of calibrated weights.

• See if Bausch & Lomb could have the component calibrated.

Probe Tip Test

• Using a CMM:– Measure spherical diameter– Measure straightness of the stem

Base & Load Arm Test

• Using a CMM verify that the dimensions match original design.

Extra Slides - Rob

Quality Function Deployment

• What the customer/sponsor wants– Functional Structure– Feasibility Assessment

• Ways to satisfy the customer/sponsor– Project Requirements– Needs Statement

• QFD Chart– Multiple ways to satisfy a need– Important to decision making process

Carrying Case

• Two Cases– Membrane Press– Electrical Components

• Lightweight

• Protects Components

• Transportability

Electrical Purchased Part Test

• Controller– Connect to Motor and Computer

• Signal Conditioner– Digital Multi-meter or Voltmeter

• Data Acquisition– Connect to Conditioner and Load Cell– Apply Force

QFD Chart

110V

inpu

t /

supp

ly

unde

r 25

lbs.

fits

in c

arry

ing

case

OR

com

plia

nt

GM

P c

ompl

iant

FD

A c

ompl

iant

seal

ed o

r dr

y be

arin

gs

min

. cu

stom

par

ts

ther

mal

mas

s <

__

load

cel

l res

olut

ion

± __

reas

onab

le Δ

t

repr

oduc

ible

load

ing

not

relia

nt o

n us

er

use

of s

tand

ardi

zed

load

ing

proc

edur

e

unde

r $5

000

auto

shu

t of

f

use

com

mer

cial

ly a

vaila

ble

cont

rolle

r /

user

inte

rfac

e

disp

lace

men

t re

solu

tion

± __

inco

rpor

ate

abili

ty t

o su

bmer

ge s

ampl

e

Safe Operation X X X X

Ease of Use X X X X X X X

Powered Conveniently X

Export Data X X X

Material Property Data X X X X X X

Accuracy / Precision X X X X X

Regulatory Agency Compliant X X X X X X

Sample Loading X X X X

Test in Saline X

Low Cost X

Feasibility Assessment Chart

Traditional Tensile Tester

Automated Membrane

Press

Manual Membrane

Press

Miniature Membrane

PressWeight/Rank I II III IV

Runs off 110V 3 0 0 - 0Low Number of Custom Parts 5 0 + + +

Easy to Dissassemble 4 0 + + +Easy Emergency Off 3 0 0 0 0

Sharp Corners 2 0 0 0 0Ease of Saline Disposal 4 0 0 0 0Test Fixture Availibility 7 0 + + +

Weight 8 0 + + +Size 8 0 0 0 +

Operating Complexity 10 0 0 - 0Cost of Material 7 0 0 0 -

Cost of Parts 7 0 0 + 0Timeline Feasibility 10 0 0 0 0

Throughput Time 8 0 0 - 0Murphy Factor 7 0 0 - 0

Component Availability 5 0 0 + +Necessary Shop Skills 7 0 0 0 0

Easy to Start 3 0 0 0 0Consistent Operation 9 0 0 - 0

Pluses 0 24 36 37Minuses 0 0 37 7

Total 0 24 -1 30

Concepts

Extra Slides - Chris

Membrane Slip Calculation

R

Fx

Fy

θ

F

Membrane

Applied Force

O-Ring

Assume: μ = 0.3 and θ = 20˚Area (A) = 3.37mm * π * 0.3mmA = 3.176mm2

P = Fspring / A = (26.7 N) / (3.176mm2 * (1e6m2/1mm2)) = 8.4x106 N/m2

R = F / cos70 = 0.2868 NFx = R * sin70 = 0.2695 N

Factual, x = 0.2695 N

Fallow = Fspring * .3 = 8.28 N

Fallow, x = 8.28 N

Factual<Fallow,x therefore membrane will not slip

Part #10201 – Translating Stage

Part #10202 – Load Cell

Part #10206 – Spherical Tip Probe

Part #11101 – Base Upper Section

Part #11102 – Base Lower Section

Part #11203 – Load Arm Base

Part #11204 – Load Arm Bracket

Part #11205 – Probe Adapter

Part #11301 – Membrane Clamp Lower

Part #11302 – Membrane Clamp Upper

Part #11303 – Membrane Clamp Spring End

Part #11304 – Saline Bath