Multidisciplinary Engineering Senior Design Project 6218 Miniature Membrane
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 engineer Kristina Schober – Mechanical Engineer Robert Mc Coy – Electrical Engineer Team Mentor: Dr. Elizabeth De. Bartolo Kate Gleason College of Engineering Rochester Institute of Technology
Agenda • • • Introduction Recap of Project Planning Fabrication and Build Lab. View™ 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 • Lab. VIEW compatible CMM Style Probe Tip • Tightly toleranced diameter 10 gram Load Cell • ± 0. 03 gram resolution • Safety pins help prevent damage • Lab. VIEW compatible
Electrical Components • Connect Load Cell to User Interface – Signal Conditioner • Accuracy: ± 0. 05% of FS • Noise and Ripple: Less than 5 m. V P-P at gain=1000 – Data Acquisition • 8 Single-Ended, 12 -Bit Analog Inputs • Lab. VIEW Drivers and Examples
Electrical Components • Connect Linear Stage to User Interface – Single-Axis Low-Power Motion Controller/Driver • Compatible for plug-and-play operation • 1000 x programmable micro-step resolution for ultra smooth low speed stepper positioning • RS 232 communications link for easy user interfacing • Lab. VIEW Compatible with Drivers
Control and Display • • Lab. VIEW interface USB and Serial port links for data input DLL files Lab. VIEW drivers Load Cell Signal Conditioner/ Amplifier USB Data Acquisition / A/D Converter Lab. VIEW® Motorized Linear Stage/Encoder Motion Controller/Driver
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 data
Replication • Replication of area of interest • Systematically scatter along xaxis
Replication, Curve Fitting & Placement • Theory dictates Pµd 3 • Cubic is fit to each curve • Best fit means best placement
“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
Investigation of Artificial Rhexis
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
Concentricity Testing (BLP 0001) • 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
Concentricity Testing Results
Offset Testing (BLP 0002) • 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 95 th and 50 th percentiles of the centered x and y positions.
Offset Testing Results Radius: Mean=0. 0049 Stdev=0. 0031
Offset Testing Results • Young’s Modulus Values:
Realignment Testing (BLP 0003) • 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
Realignment Testing Results
Gage R&R (BLP 0004) • 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 95 th percentile
Error Analysis
Results • PVDC (plastic wrap) – 352. 7 MPa ± 50. 2 MPa • Artificial Rhexis – 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 üCompact and easily transportable design. üIncorporate ergonomics. Overall weight < 25 lbs. üCarrying case. Compliant with FDA, GMP, and OR regulations. üEasy to operate user interface. üSterilization using autoclave. üLoad cell and encoder capable of continuous data acquisition. üRepeatable mounting of specimens. üRepeatable method of generating a sample out of the original rhexis. üPowered by 110 V outlet. üAbility to test a sample that is submerged in a saline solution. Cost to be on the order of $5, 000.
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