multidisciplinary engineering senior design project 6218 miniature membrane press critical design...

Multidisciplinary Engineering Senior Design

Project 6218 Miniature Membrane Press Critical Design Review

5/16/2006

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• Recap of Project Planning• Fabrication and Build• LabView™ Development• Data Analysis Routine• Testing & Results• Error• Recommendations• Demonstration

Introduction

• Purpose is to gather material properties

• Employing a nontraditional method of property determination

• Showing much promise

Design Layout

Design (cont.)

Component Selection

Motorized Translating Stage:•±0.1 μm resolution•Built in linear encoder•LabVIEW compatible

CMM Style Probe Tip•Tightly toleranced diameter

10 gram Load Cell•±0.03 gram resolution•Safety pins help prevent damage•LabVIEW compatible

Electrical Components

• Connect Load Cell to User Interface– Signal Conditioner

• Accuracy: ±0.05% of FS• Noise and Ripple: Less than 5 mV P-P

at gain=1000

– Data Acquisition • 8 Single-Ended, 12-Bit Analog Inputs• LabVIEW Drivers and Examples

Electrical Components

• Connect Linear Stage to User Interface– Single-Axis Low-Power Motion

Controller/Driver • Compatible for plug-and-play

operation • 1000x programmable micro-step

resolution for ultra smooth low speed stepper positioning

• RS232 communications link for easy user interfacing

• LabVIEW Compatible with Drivers

Control and Display

• LabVIEW interface• USB and Serial port links for data input• DLL files • LabVIEW drivers

Load Cell

Signal Conditioner/

Amplifier

USB Data Acquisition /

A/D Converter

Motorized Linear Stage/Encoder

Motion Controller/Driver

LabVIEW®

Alignment VI

Test VI

Data Operations

• Purpose– Necessary to extract material properties– To account for not sensing origin

Representative Data Set

• Smoothness & Continuity

• Noise contaminated zero values

• Characteristic curve• Both Small and large

deflection data23.8 23.85 23.9 23.95 24 24.05 24.1 24.15 24.2 24.25

0

1

2

3

4

5Plot of Raw Data

Position (mm)

For

ce (

gram

for

ce)

Readings Before Contact

Area of Interest

Replication

• Replication of area of interest

• Systematically scatter along x-axis

0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0.10

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1Plot of Conditioned Data

Deflection (mm)

For

ce (

gram

for

ce)

Replication, Curve Fitting & Placement

• Theory dictates P3

• Cubic is fit to each curve

• Best fit means best placement

0 0.02 0.04 0.06 0.08 0.1 0.120

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

For

ce (

gram

for

ce)

Deflection (mm)

Conditioned Data with Curve Fit Overlay

Most capable of being fittedby the cubic function

“Small” Deflections

• Question: What is “small?”

• Answer: Data points corresponding to the part of the data curve that have yet to deviate from the small deflection equations’ predictions

Investigation of Plastic Wrap

Comparison of Data vs. Small Deflection Equation

0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0 0.05 0.1 0.15 0.2 0.25

Displacement (mm)

Fo

rce

(N)

E = 354.37 N/mm 2̂ (smalldeflection eq.)


Experimental Data

Investigation of Artificial Rhexis

Comparison of Data vs. Small Deflection Equation

0

0.001

0.002

0.003

0.004

0.005

0.006

0.007

0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4

Displacement (mm)

Fo

rce

(N)



Experimental Data

Implementation Methods

• Two methods of Data Analysis– MATLAB®

• More Robust• Fast• Easily Customizable

– Microsoft Excel®• Easier to adjust• Microsoft Excel® is more readily available

MATLAB® Implementation

Excel® Implementation

Poor Data

• Obvious anomaly in the data curve

• Severe impact on modulus readings

• Suspected to be from wrinkles or poor sample loading

23.85 23.9 23.95 24 24.05 24.1 24.15 24.2 24.250

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1Data Comparison

deflection (mm)

gram

for

ce (

g)

Favorable Data

Areas of Concern

Concentricity Testing (BLP0001)

• Objective: – To evaluate the membrane press alignment. It is

critical that the probe tip and stage be centered.

• Procedure– Set alignment prior to each test and record position per

SOP#: TD-PPD-PRO-001.– Use 10 different samples.

• Results: – The data provided a range for the center point location.– Favorable data results of Young’s Modulus.

Concentricity Testing Results

Radius: Mean=0.0056 Stdev=0.0024

r x x y yavg n avg n ( ) ( )2 2

Concentricity Testing: Various positions of the probe tip

0.45

0.454

0.458

0.462

0.466

0.47

0.474

0.478

0.5340.538

0.5420.546

0.550.554

0.558

x-position(in)

y-p

os

itio

n(i

n)

Centered Probe tiplocationsAverage

Favored Data

Concentricity Testing Results

Young's Modulus Values from Concentricity Test

0

1

2

3

4

5

6

24.05 24.1 24.15 24.2 24.25 24.3 24.35 24.4

Stage position (mm)

Fo

rce

(g) Test 1

Test 6

Test 7

Test 9

Young's Modulus (N/mm2) R2

377.8 0.9992426.5 0.9993296.7 0.9993309.7 0.9987

Average= 352.675STDEV= 60.722

Offset Testing (BLP0002)

• Objective: – To evaluate the membrane press with an offset

alignment. – A worst case scenario.

• Procedure: Determine the offset value, running 10 tests at the offset position.– Determining the offset value:

• Used centered data collected from the Concentricity Tests.

• Found the 95th and 50th percentiles of the centered x and y positions.

95th Percentile= 0.551


x-direction

x-displacement0.006



y-direction

0.004y-displacement

Offset Testing Results

Radius: Mean=0.0049 Stdev=0.0031

Offset Testing: Various positions of the probe tip

0.458

0.462

0.466

0.470

0.474

0.478

0.5400.544

0.5480.552

0.5560.560

0.564

x-position(in)

y-p

osi

tio

n(i

n)

Location of probe

Average location

Favored Data

Offset Testing Results

Young's Modulus (N/mm2) R2

599.3 0.9977265.3 0.9872294.4 0.999272.9 0.9984451.9 0.9997

Average= 376.760STDEV= 145.914

•Young’s Modulus Values:

Young's Modulus values from offset testing

0

1

2

3

4

5

6

24.1 24.15 24.2 24.25 24.3 24.35 24.4

stage position (mm)

forc

e (g

ram

s)

test2

test4

test5

test6

test9

Realignment Testing (BLP0003)

• Objective: – To reduce the number of times the stage must be

realigned.

• Procedure:– Run 10 tests, 5 tests, and 2 tests.

• Acceptance Criteria: • Results: After each test the device must be realigned

After Test # Left side Right side Center After Test # Bottom Top Center0 0.5252 0.5505 0.5379 0 0.4571 0.48 0.46866 0.519 0.549 0.5340 6 0.4575 0.4809 0.4692

Difference= 0.0038 Difference= 0.0006

X-Direction Y-Direction10 Tests

x-position= 0.006y-position= 0.004

Realignment Testing Results







Gage R&R (BLP0004)

• Objective: Measure the Repeatability and Reproducibility of the device.

• Procedure:– 3 operators

– 10 different samples a piece

• Acceptance Criteria: Less than or equal to 25%

• Results: – Gage R&R= 383%

Testing for Misalignment Induced Error

95th percentile

95th percentile

E MPa 2 4 1.

Error Analysis

E

E

P

P

a

a

h

h

R

R

E MPa

9

4

1

43

2 6 2

.

EPa

hR

1 6

9

9 4

1 4 3

/

/

Results

• PVDC (plastic wrap)– 352.7 MPa ±50.2 MPa

• Artificial Rhexis– MPa ±14.3%– MPa ±14.3%

Recommendations

• Eddy current or capacitance sensors

• Negative pre-strain testing

• Saline testing

• grip redesign

• Continued silicone testing

• Fitting non-linear constants

• Shorter

Questions & Discussion

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.

multidisciplinary engineering senior design project 6218 miniature membrane press critical design...

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