Design and Fabrication of a Micro-Tensile Test …rbb.union.edu/data/RBB Sr Projects/2016...
Transcript of Design and Fabrication of a Micro-Tensile Test …rbb.union.edu/data/RBB Sr Projects/2016...
Poster Design & Printing by Graphic Arts Center
Design and Fabrication of a Micro-Tensile
Test System for In Situ Optical Microscopy
Introduction and Background
.
Data Acquisition System
A load cell measures the force on one crosshead (and thus on the
specimen) while displacement is measured by tracking the crosshead
with a linear displacement sensor. Both sensors were calibrated to relate
voltage output to displacement and force. Data is recorded on Matlab in
real-time using a Graphical User Interface. The system is also compatible
with StrainSmart software and hardware.
Final Design
The Stage Specifications are:
• 100lb Load Capacity
• 32.5cm*18.3cm*2.7cm Footprint
• Submicron Resolution
• Low Force and Displacement Noise
• Coarse and Fine Strain Adjustment
• StrainSmart and Matlab Compatible
• $1800 Price Tag (Including Sensors)
Conclusions and Recommendations
Acknowledgements
• Ronald B. Bucinell, Ph.D., P.E.
• Paul Tompkins
• National Science Foundation CMMI-1362234
• Student Research Grant
• Rhonda Becker
Senior Project-Mechanical Engineering-2016
Fig 1: Tensile Stage SolidWorks Design
Diminishing nonrenewable resources such as petroleum used in the
manufacturing of synthetic plastics and the carbon footprint of the
manufacturing processes have prompted interest in finding greener
alternatives such as biomaterials. To successfully use them, it is crucial to
characterize their mechanical behavior, and understand the microstructural
properties underlying such behavior. This knowledge can also help in
successfully manipulating the microstructure of biomaterials to obtain desired
mechanical properties.
To perform microscopic characterization, the material is loaded while
observing its microstructure under a microscope. Micro-tensile stages are
miniature versions of Universal Testing Machines that can be placed inside or
under different types of microscopes. Currently, there is no capability to
perform such tests as the tensile stage is too big to fit under the microscope.
Therefore, the objective of this project was to design and build a new tensile
stage that fits under the Olympus BX-15 optical microscope, and can
accommodate the 1000x optical lens and different test fixtures.
The final SolidWorks design that
was used in the fabrication and
assembly of the new tensile stage
is shown in Figure 1. The design
incorporates commercial drive
components and CNCed
aluminum parts. To stretch the
sample, the user turns the dial and
the gear train translates the motion
into symmetric linear crosshead
displacement. Figure 3 is the final
manufactured stage.
Fig 3: Fabricated Tensile Stage Fig 2: Microscope Integration
y = 2277.2x + 1681.7 R² = 1
-1000
0
1000
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-1 -0.5 0 0.5 1 1.5 2 2.5
Mass(g
)
Voltage (V)
Mass vs Voltage for 100lb Load Cell
Fig 5: Block diagram of DAQ system (left) and
data collection algorithm (right)
Fig 5: Setup for load cell calibration (left) and the
resultant calibration curve(right)
To test the functionality of the stage, a tensile test was conducted on a
rubber specimen to obtain the force versus displacement curve shown
below. The second curve was obtained using StrainSmart software and
hardware, while driving the stage with a drill instead of a hand dial to
evaluate the concept of a motorized stage.
Fig 6: Force and Displacement curves for a silicon rubber specimen on Matlab and StrainSmart
A low cost tensile stage that is compatible with the microscope in
the Materials Lab was successfully designed and built. While the
system functions well, the addition of a motor will reduce noise
associated with moving the dial as well as prevent the discomfort on
the hand of the operator. Due to the stage’s weight, a multi axis
platform will make it easier to move the stage instead of using the
microscope platform.
Fig 3: Noise test on the load and displacement
sensors
Zibusiso Dhlamini
Advisor: Professor Ronald B. Bucinell, Ph.D, PE.