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 2000 3000 4000 5000 6000 7000 8000 -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.