CellScale UniVert User manual

UniVert
Mechanical Test System
User Manual
version 1.9

Mechanical measurement and analysis of materials
CellScale provides scientific and medical researchers with turn-key systems for
measuring the mechanical properties of materials. We provide user-friendly
software, an easy-to-use patented attachment system and effective data analysis
tools.
Our foundation was laid at one of the world’s leading research institutions –the
University of Waterloo. We understand research and aim to provide effective
solutions at a reasonable price.
Explore our web site www.cellscale.com or contact us to learn more about our
measurement systems.
© 2020CellScale. All rights reserved. This material may not be reproduced,
displayed, modified or distributed without the express prior written permission of the
copyright holder. For permission, contact CellScale Biomaterials Testing at
[email protected].
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Table of Contents
1. General Information.................................................................................................................. 1
Environmental and Electrical Specifications................................................................................ 1
System Assembly......................................................................................................................... 1
Connections to Supply................................................................................................................. 1
Safety Warnings........................................................................................................................... 2
Manual Operating Controls.......................................................................................................... 2
General Maintenance................................................................................................................... 2
Approvals and Certification.......................................................................................................... 2
2. Testing Terminology................................................................................................................. 3
Multiphase Test Cycles................................................................................................................ 3
Phases, Cycles, and Test Sequences......................................................................................... 4
Test Phases: The Smallest Unit of Testing.................................................................................. 5
Control Modes.............................................................................................................................. 5
Control Functions......................................................................................................................... 5
Test Modes .................................................................................................................................. 6
3. Software Overview ................................................................................................................... 7
Output Files and Data Structures................................................................................................. 8
4. Setting Up & Starting a Test..................................................................................................... 9
Overview...................................................................................................................................... 9
Step 1: Start a New Test.............................................................................................................. 9
Step 2: Reset the Actuator......................................................................................................... 10
Step 3: Specify Test Type.......................................................................................................... 11
Step 4: Move the Actuator to a Specified Size .......................................................................... 11
Step 5: Zero the Load Cell (occasionally).................................................................................. 12
Step 6: Modify Testing Parameters (optional) ........................................................................... 12
Step 7: Mounting a Specimen.................................................................................................... 14
Platen Mounted Specimens ................................................................................................... 14
Grip Mounted Specimens....................................................................................................... 15
3-Point Bend Specimens........................................................................................................ 17
Step 8: Execute the Test............................................................................................................ 18
Step 9: Terminate the Test Prematurely (optional).................................................................... 18
5. Additional Settings.................................................................................................................. 19
Configuring Output Data Files.................................................................................................... 19
Advanced System Settings Dialogue......................................................................................... 20
Range Limits.............................................................................................................................. 22

Configuring the Live Charting Graphs ....................................................................................... 23
6. Reviewing Test Results.......................................................................................................... 25
Overview.................................................................................................................................... 25
Selecting Images........................................................................................................................ 26
Image Playback Options............................................................................................................ 26
Image Tracking: Overview ......................................................................................................... 27
Image Tracking: The Points Display Option .............................................................................. 30
Image Tracking: The Displacement Option ............................................................................... 31
Image Tracking: The Strains Option.......................................................................................... 32
Data Overlay.............................................................................................................................. 33
Exporting Tracked Data ............................................................................................................. 34
Exporting Images and Movies.................................................................................................... 35
7. System Hardware Settings..................................................................................................... 36
Controller.................................................................................................................................... 36
Camera ...................................................................................................................................... 36
Load Cell.................................................................................................................................... 37
Actuator and Motor .................................................................................................................... 38
Temperature............................................................................................................................... 38
8. System Calibration and Advanced Tools ............................................................................... 40
Load Cell Calibration.................................................................................................................. 40
Alternate Method.................................................................................................................... 43
Zero Position Calibration............................................................................................................ 45
System Stiffness Compensation................................................................................................ 48
Snap Image Feature .................................................................................................................. 51
Update Firmware........................................................................................................................ 51
9. Troubleshooting...................................................................................................................... 52
Communication Errors: Read File failed with error 6................................................................. 52
Actuator Limits ........................................................................................................................... 53
Appendix A: Unpacking and Initial Setup ...................................................................................... 56
Tools .......................................................................................................................................... 56
Components and Fasteners....................................................................................................... 56
Appendix B: Load Cell Installation................................................................................................. 63
Appendix C: Software Installation.................................................................................................. 65
Appendix D: Test Setup................................................................................................................. 71
Choosing and Installing a Riser for the Bottom Grip, Platen, or 3 Point Bend Block ................ 71
Tension Test Setup ................................................................................................................ 73
Compression Test Setup........................................................................................................ 76

3-Point Bend Test Setup........................................................................................................ 78
Appendix E: Camera Setup........................................................................................................... 81
Webcam..................................................................................................................................... 81
Scientific Camera....................................................................................................................... 83
Appendix F: Media Bath Setup...................................................................................................... 86
Appendix G: Changing Grip Springs ............................................................................................. 91
Appendix H: Changing Grip Springs (Legacy Grips)..................................................................... 96

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1.General Information
The UniVert is a precision test instrument designed for the compressive and tensile testing and
analysis of materials including metals, polymers, and biological specimens. The system includes
a test station and an integrated software interface to run and analyze test results.
Environmental and Electrical Specifications
Electrical Input
100-240VAC, 50-60Hz
Current Rating
1.67 Amp
Environmental Conditions
Maximum Operating Temperature 25ºC
0% - 95% Relative Humidity
Installation Category
Category II
Pollution Degree
Degree 2
Data Connections
1 –USB for camera/PC communication
(USB 3.0 for scientific camera)
1 –USB for controller/PC communication
System Assembly
Some basic assembly and setup is required. An unboxing and setup guide can be found in
Appendix A.Load cell installation is detailed in Appendix B and software installation is
described in Appendix C. Camera setup is described in Appendix E.
Connections to Supply
Connect power supply into properly grounded 100-240VAC power source to ensure safe
operation. Ensure that the power cord is easily accessible at all times. The use of an
Uninterruptible Power Supply (UPS) is recommended to protect against data loss.
The mains supply voltage fluctuations should not exceed 10% of the nominal supply voltage.

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Safety Warnings
This equipment must be used in accordance with the procedures outlined in this manual.
Operators of this equipment must be instructed in safe operating procedures to prevent injury
and/or damage.
Ensure that the area around the moving actuator is clear before commencing test protocols.
The UniVert presents a pinch hazard to extremities. Keep hands clear of moving parts for the
duration of the test.
System Alert
This equipment must not be disassembled by the user or modified in any way.
Manual Operating Controls
There is a single power switch on the front of the control unit to turn on the UniVert.
General Maintenance
Clean the system as needed with mild soap and water or alcohol based cleaning solutions.
Approvals and Certification
This product conforms to applicable CE standards.

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2.Testing Terminology
The UniVert is designed to apply uniaxial compressive and tensile forces to a variety of materials.
This includes metals, plastics, and composites as well as biological materials.
Multiphase Test Cycles
In order to properly characterize and test a specimen, it is often necessary to load it to different
degrees and at different rates. There are three main reasons for doing this:
Preconditioning–Especially for biological specimens, the goal of preconditioning is to
restore a specimen to its physiological or in vivo state. During the process of specimen
storage and preparation, a specimen may swell, dry out, have its material fibers realign, or its
molecules reorganize. It may take multiple preconditioning cycles for a specimen to be
restored to its natural state.
Reproducing Physiological Conditions During Testing - By applying various loads and
load rates, natural expansion and contraction of a specimen can be reproduced (for example,
the pulse pressure in an organ). In as much as the physiological conditions can be recreated,
the specimen can be tested in a more realistic state.
Varying Test Conditions - Variable loads and rates allow you to create a variety of test
profiles to best study your specimen.

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Phases, Cycles, and Test Sequences
As the following diagram demonstrates, each application and release of load on the specimen is
called a test cycle. The same test cycle can be repeated multiple times to achieve a certain goal
(preconditioning, physiological conditioning, or testing); this is called a test set. Finally, a test
sequence is made up of multiple test sets.
The above example describes the following:
•The entire diagram presents a full test sequence.
•Within that sequence, there are two test sets: the first set applies preconditioning to the
specimen; the second set executes the actual test on the specimen.
•Within the first set (preconditioning), two identical test cycles are implemented to bring
the sample to a satisfactorily preconditioned state.
•Finally, the second set (testing) is made up of three cycles.

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Test Phases: The Smallest Unit of Testing
The test phase is the smallest unit of the test specification. There are five phases within a cycle.
Each phase serves a specific purpose:
Preloading- Preloads are applied to bring a test
to a well-defined starting point. Because the
dimensions of a specimen may change as a
result of a loading cycle (stretching of fibers,
viscoelastic effects, plastic deformation, or
localized material failure at the attachment
points), the preload adjustment compensates for
any of these changes in specimen geometry.
Stretching - During the stretch phase, a
deformation is applied to the specimen. The
deformation can be specified either in terms of
force applied or displacement achieved.
Holding - The deformation can be held for a given duration. The duration for which it is
held is dependent on the nature of the testing.
Recovering - The recovery phase is the time during which the force being applied to
the specimen is removed. The duration of the recovery time is configurable and
dependent on the nature of the testing.
Resting - Finally, the rest phase is the time between the end of one cycle and the
beginning of the next. Some tests may specify a short recover time, while others may
specify a longer time. The duration is configurable and dependent on the nature of the
testing.
Control Modes
There are two control modes which define the basic approach to a given test: displacement
control and force control:
Under displacement control, the displacement of the specimen is predefined. The
UniVert stretches or compresses the specimen until the predefined displacement is
achieved. The force required to achieve the displacement is an output of the test.
Under force control, the force applied to the specimen is predefined. The UniVert
stretches or compresses the specimen until the predefined force is achieved. The
displacement required to achieve the force is an output of the test.
Control Functions
The UniVert makes it possible to test specimens under several control functions:
Under displacement control:
The true strain function applies the displacement at a true strain rate, which accounts
for the current specimen length while the specimen is being stretched. The UniVert
system approximates this with a series of linear segments (default = 10).
The ramp function applies the displacement at a constant nominal rate. This is
equivalent to engineering strain or constant velocity.
The sine function applies the displacement according to a sinusoid with the desired
displacement magnitude and duration. The UniVert system approximates this with a
series of linear segments.

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Under force control:
The step function achieves and maintains the desired force as quickly as possible. The
amount of time it takes to achieve the desired force depends on the material being tested
and the force control settings.
Step
Time
Force
Test Modes
There are three test modes that can be used when performing a test: tension, compression, and
3-point bending.
Tensile Test - This test mode is used in combination with provided specimen grips. In this mode,
positive displacement is in the direction of increased fixture separation and tension forces are
positive.
Compression Test - This test mode is used in combination with provided compression platens.
In this mode, positive displacement is in the direction of decreased fixture separation and
compressive forces are positive.
3-point Bend Test - This test mode uses the same displacement and force convention as
compression testing but is applied to a 3-point bend setup.

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3.Software Overview
The software included with the UniVert device is called UniVert. It is divided into two modules, a
data collection module and a review and analysis module. The data collection module is used to
set test parameters, enable specimen loading and testing, and monitor test progress. The screen
layout for this module is shown below:
Test
Parameters
Live Force &
Displacement
Live Video Live Charting
The review and analysis module is used to playback accelerated or decelerated test images,
perform image analysis and tracking, and output movie files for presentation purposes. The
screen layout for this module is shown below:
Image List
Image
Playback
Image
Tracking
Data
Overlay

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Output Files and Data Structures
For each test, the UniVert creates and saves three file types. The following table describes the
three file types for a project named “Sample1”. Output from this test would be found in a
“Sample1” output directory (a sub directory of the user specified data directory).
File Type
Description
.tst file
The Sample1.tst file that contains the exact protocol and settings used for the test.
.csv file
The Sample1Data.csv file that contains comma separated numerical data such as time, force and
displacement values.
.jpg files
Captured images such as Sample1.000010.3.jpg, which would correspond to an image captured
at 10.3 seconds from the start of the test.
Each test folder will also contain 2 subfolders. The “Logs” subfolder contains a text file of the
content of the text dialogue portion of the main screen. It is useful as reference to troubleshoot
problems with your system, should they occur.
The “Tracking” subfolder is initially empty. If tracking is done on any of the images in the test
folder using the “Analyze and Review” software module, there will be data files that contain the
tracking information stored in this directory.
While using the “Analyze and Review” software module, you may create additional data files such
as text files (*.csv) containing tracking results, images with force data or tracking results overlaid
(*.wmf), or movie files (*.avi). These additional files can be stored in the test directory or
elsewhere on your computer’s hard drive without interfering with the software application (once
created, they cannot be opened by the UniVert application).
When working with the data, you should be aware of a few details regarding the data output:
1. The output specimen size is based on the spacing between the grips or platens and does
not account for the specimen material outside of the test region.
2. The software cannot calculate stress since the thickness of the specimen is not known.
To calculate stress, you will have to manually measure the thickness of the material
before or after the test is performed.
3. Strains can be calculated using the output displacement values (which are based on the
grip or platen motions). The specimen may actually be subjected to less strain than the
calculated values due to attachment site effects. The image tracking module is useful for
determining the actual strain values and variations within the specimen.

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4.Setting Up & Starting a Test
Overview
Setting up and running a new test is a simple process made up of both mandatory and optional
steps. The following list presents all of the steps, while the rest of this chapter describes each of
the steps in detail.
Step 1: Start a New Test
Step 2: Reset the Actuator
Step 3: Specify Test Type
Step 4: Move the Actuator to a Specified Size
Step 5: Zero the Load Cell (occasional)
Step 6: Modify the Test Parameters (optional)
Step 7: Mount the Specimen
Step 8: Execute the Test
Step 9: Terminate the Test Prematurely (optional)
Step 1: Start a New Test
Launch the UniVert software and then select Collect New from the File menu.
In the Create Test From Template dialog, perform the following steps:
1. Select a template that matches the type of test you wish to perform. See the UniVert Tip
on how to select and use a template. You can modify the template parameters in Step 4,
below.
2. Name your test. The dialog will have a default test name. You can use the default or
rename the test. Each time you start a new test, the default name will continue to
increment the number at the end of the name.

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3. If desired, you can change the location of the output data. The location of your output
data and images is determined by specifying a Test Name and Data Directory. The
template and data directories are user specific (computer login name). Each system user
can store their files to a different default location. The system uses the last location
selected as the default.
UniVert Tip: Selecting and Using Templates
How to select a template: Designing an appropriate test sequence is an art that
depends on both the type of material being tested and the specific material properties
you are interested in measuring. When first testing a new material, you should expect to
have to experiment with the settings until the test yields meaningful data.
The system comes loaded with example templates to help you get started. Selecting a
template does not lock you into a specific test sequence or protocol –rather a template
defines a test sequence and settings, all of which can be changed before a test is run.
Once you have developed a test sequence and settings that are appropriate for the
material you are testing, you should save these settings using “Save As Template” from
the File menu. You can then select your template the next time you initiate a test.
Step 2: Reset the Actuator
We suggest performing a reset at the start of a new test session. This command sends the
actuator to its fully retracted position and resets the displacement value. If you have stopped the
previous test in mid cycle, then you should also reset the actuator. By resetting the actuator, you
are ensuring that the displacement measurements taken by the UniVert are accurate.
To reset the actuator, select Reset Actuator from the Tools menu, or press on the toolbar.
System Alert
You should NOT reset the actuator if the specimen is already loaded in tension. Doing
so will damage your specimen and/or the load cell.

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Step 3: Specify Test Type
Access Test Mode in the Settings menu to select the appropriate test mode and install the
platens, grips, or 3-point bend attachments (see Appendix D for this procedure).
Step 4: Move the Actuator to a Specified Size
After the actuator has been reset, it will remain in the fully retracted position and must be moved
to a specified (reference or starting) position.
To move the actuator to the specified position, select Move Actuator to Specified Size from the
Tools menu, or press on the toolbar. This size may be entered in the “Specified Size”
dialogue.

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Step 5: Zero the Load Cell (occasionally)
While it is not necessary to zero the load cell with every test sequence, we suggest zeroing the
load cell at the start of a new test session. With repeated use, the zero point of the load cell can
drift. By zeroing the load cell, you are ensuring that the force measurements are accurate.
To zero the load cell, select Zero Load Cell from the Tools menu or press on the toolbar.
System Alert
You should zero the load cell after attaching a platen or grip but before mounting a
sample. If a specimen is already loaded when the load cell is zeroed, the force reading
will include an offset load.
Step 6: Modify Testing Parameters (optional)
You can select and modify the parameters in the test
sets by clicking on a row in the Test Sequence table
and then pressing the Edit Set button (or by double
clicking on the desired row). When you do so, the Set
Parameter Editor dialog will appear.
Note that displacements are specified in either %
strain, or mm. Force loads are specified in N, and
durations are specified in seconds.
The following table describes each of the parameters.

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Test Parameter
Description
Control Mode
Tests are typically performed under displacement control, however, you can select the
following control modes to achieve specific testing objectives:
•For creep testing, use force control with a long hold duration.
•For stress relaxation testing, use displacement control with a long hold
duration.
Control Function
True Strain or Ramp is typically selected for tests performed in displacement control
mode. For tests performed in force control mode, Step controls are selected.
Stretch Magnitude
(Load Magnitude when in
Force Control mode)
Selecting a stretch magnitude is dependent on the material you are testing. A sound
approach is to begin with a small magnitude and iteratively move up to larger
magnitudes.
If you are using Displacement control mode, you can specify the displacement in either
mm or as a percentage. For example, the displacement on a 5mm specimen can be
expressed as either 0.5mm or 10%.
If you are using Force control mode, you can only specify the force in N.
Watch the test results carefully to determine which magnitude setting best achieves
your test goals.
Preload
Preload is typically reapplied on every repetition during a preconditioning set as well as
on the first repetition of a testing set. Specimen size is adjusted after a preload
adjustment. Strain calculations are based on the specimen size after the last preload
adjustment. If you are working with a material for which preload values have been
suggested, you can set the value accordingly. Otherwise, zero is a good initial choice.
Preload Magnitude
As with stretch magnitude, the preload magnitude settings depend on the material you
are testing. While Preload can be set at zero, typically you would set the preload
magnitude somewhere between zero and 10% of the peak load you expect to achieve.
Stretch Duration
For evenly spaced images, it is recommended to choose a number that is an integer
multiple of the Image Output Frequency.
Hold Duration
Hold Duration is typically set to 0, however it is useful for creep or relaxation testing.
Recovery Duration
Recovery Duration is typically set to the same value as the Stretch Duration.
Rest Duration
Rest duration is typically set to 0, however a non-zero value may be used to mimic in
vivo conditions or for specialized testing.
Repetitions
Apply enough repetitions until the force deformation curves from one repetition to the
next start to overlie each other.
Data Output Frequency
Typically set to the same frequency as the image output frequency.
Image Output Frequency
Typically set to 1Hz for cycles > 5 seconds and 15 Hz for cycles < 5 seconds.
UniVert Tip: Idle Current
Idle current (holding current) can be applied to the motors. The motors have a holding
force in the de-energized state of approximately 100N. If forces in excess of 100N are
expected it is recommended that idle current is used to prevent position loss during
velocity and direction changes when the motors are de-energized for a very short time.
When idle current is activated the motors will produce more noise, even when the
actuator is at rest. This setting may be accessed by selecting Hardware from the
Settings menu.

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Step 7: Mounting a Specimen
Platen Mounted Specimens
1. Select an appropriate riser to accommodate the size of the specimen (see Appendix D).
2. Place the specimen on the bottom platen.
3. Jog the top platen to the correct position using the jog arrows in Actuator Control
Alternately, the Move Actuator to Specified Size command may be used.
UniVert Tip: Compression Specimen Mounting
Make sure to center the specimen on the platen as much as possible to ensure
accuracy in the force reading. Ideally, specimens will have two parallel flat sides and will
make full contact with both platens. Although this is not always possible, flat testing
surfaces will improve force distribution.

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Grip Mounted Specimens
Low Force Grips
1. Select an appropriate riser to accommodate the size of the specimen (See Appendix D).
2. Select a spring with an appropriate clamping force for the specimen being tested (see
Appendix G for more details).
3. Jog the actuator using Actuator Control or select Move to Specified Size until the grips
are sufficiently far apart and attach the specimen to the top grip.
4. Using Actuator Control, lower the top grip (with specimen attached).
5. Open the bottom grip and lower the specimen between the grip surfaces. Release the
bottom grip.