Metrology

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Metrology

• Transducers and Amplifiers

By Eric Sanchez and Rodrigo Barbosa Advisors
Dan Wilson and Bruce Kutter
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Geotechnical Modeling
Centrifugal modeling consists in studying
geotechnical problems such as stiffness, capacity
of bridges and building among others. By applying
gravitational acceleration to physical models,
the centrifuge produce identical self-weight
stress in the model and prototype. In this way,
centrifuge modeling provides data use to help our
understanding of mechanical deformations.
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Introduction
Metrology It is the scientific study of
measurement. This plays a critical role in
geotechnical modeling and all engineering work
due to its importance to acquire data.
Metrology use in the Centrifuge A large inventory
of transducers and signal conditioning
equipment can be used to monitor model behavior
during an experiment. Currently, up to this
facility is able to use 160 transducers and can
be expanded as need arises. All these devices
must be calibrated in order to get the accurate
data for researchers
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Purpose

• Using real-time data, to analyze earthquake.
• Finding ways to make our measurements more
  accurate in centrifuge testing.
• Ensuring that standards of measure meet specified
  degrees of a accuracy and precision.

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How It Works

• Sensors detects signals or stimulus and produces
  a measurable output.
• Amplifiers are the basic building blocks for
  earthquake simulation.

PHYSICAL STIMULUS
SENSOR
AMPLIFIER
DIGITIZER
BITS TO UNITS (MATH)
UNDERSTANDABLE KNOWLEDGE
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PVL Amplifier

• There are three amplifiers in the facility and
  each
• one has 16 independent channels. Two out of three
  of
• them are variable with gains of 1 to 1000 and
• the other one as a fix gain of 100.

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PVL Circuit Amplifiers

• High accuracy instrumentation amplifier that
  requires only external resistance to set gains of
  1 to 1000
• Low offset voltage ideal for precision data
  acquisition systems such as weigh scales and
  transducer interfaces.
• Low noise

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Interface Box CX-0404
This CX-0404 interface box has calibrated
voltages which will be compare to the ones we
have in the amplifier to see how accurate our
values are. These Output settingsmV/V are
0, 0.04, 0.08, 0.2, 0.4, 0.8, 1.2,
1.6, 2.0, 2.4, 3.2, 4.0, 4.4
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Table
FLEX INTERFACE
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2
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AMPLIFIER

• READ OUTPUT IN THE COMPUTER
• TO SET THE OFFSET VOLTAGE
• TO MEASURE EXCITATION VOLTAGE
• INPUT VOLTAGE
• CONNECTION TO DC. SUPPLY
• CABLE TO GROUND

INTERFACE CX-0404
DC. SUPPLY
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Data

• Excitation voltage.
• Input and output voltage.
• Tables and Graphs.
• Intercept, Slope, and R2 values.
• Collected data.
• Calibration certificate
• Access Data Base

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Calibration of Load Cells
Phase 1
Phase 2
Phase 3
Create a mechanism to develop a reliable way for
calibration
Learning about transducers and Load cells
Testing Load Cells
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Load Cells
A load cell is a transducer that converts a force
into a electrical signal. There are several
different types of load cells.
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Calibration Load Cell
SSM S-Type
SML Low Height
Low Capacity
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Calibration Using Weights
Interface Load Cell 1500AZB-100
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Interface Load Cell 1500AZB-100
Weights
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Actuator Calibration

• Development of a reliable technique for
  calibration

• Efficiency
• Accuracy
• Time Saving

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Actuator
Load Cell
Strain Gage Amplifiers
Reactor
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Interface SML-1000 181325
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Conclusion
We worked to create ways of improving the
calibration systems use nowadays. In this way,
earthquake simulations will become more accurate
in increasing safety matters during these
catastrophes.
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Acknowledgements

• As REU students we would like to give special
  thanks to
• Bruce Kutter Director
• Dan Wilson Operation Manager
• Cypress Winters Safely Officer
  Administrative/Clerical Staff
• Ray Gerhard Assistant Development Engineer
• Chad Justice Technician
• Tom Kohnke Technician