A Virtual Simulation Experiment of Mechanics: Material Deformation and Failure Based on Scanning Electron Microscopy

The system may be used to instruct our students in experimental protocols, equipment use, and the theoretical verification, allowing them to repeatedly enhance their operations and the laboratory skills. A side of three dimensional virtual simulation experiments can be conducted to detect the material deformation and the failure without fear of harming the physical system or injuring themselves. After accessing and entering the interface, follow the guidance provided in the picture to virtually reach the high temperature universal creep testing machine, and place the stack specimens between the plate clamps of the machine.

Once the virtual computer on the left side of the testing machine is highlighted, click on the virtual computer and set the test scheme on the control computer of the machine. Then click on the highlighted heating and vacuum pumping equipment and turn on the power supply. Open the virtual mechanical pump and backing valve in the interface by clicking on the respective highlighted buttons to complete the system vacuum control settings.

On the control panel in the universal creep testing machine, click the clear button to clear the data, followed by clicking the run button to complete the experiment of copying the pattern on the mold to the metal sheet using the parallel plate compression molding method. After completing the mold casting, click on the virtual computer again and check the experimental data on the control computer of the universal creep testing machine. Open the cover plate on the metallographic specimen inlaying machine, and place the specimen.

To pour the prepared powder, click on the highlighted polymethyl methacrylate, or PMMA powder. Then click on the highlighted mold to place it on top of the PMMA powder. Next, click on the highlighted hand wheel and adjust the position of the mold to cover the cover plate automatically.

Click the on, off button to turn on the inlaying machine. Take out the inlaid PMMA specimen after cooling. Enter the room for polishing and corrosion following the pathway guidance shown in the picture.

Find the highlighted polishing machine and click on the gripper of the machine to mount the inlaid specimen to the gripper. Set the speed to grind and polish the specimen by removing the molded material substrate. Grind the mold on one side until the pattern on the mold is exposed.

For performing specimen characterization, virtually open the chemical storage cabinet and take out the solid potassium hydroxide. Click on the highlighted beaker and solid potassium hydroxide for corrosion liquid preparation to make a 10%potassium hydroxide solution. Select the highlighted potassium hydroxide solution and the specimen to corrode the ladder into a metallographic specimen.

Next, clean the specimen after removing the silicon substrate and run a characterized testing with a prepared specimen under an optical microscope. Load the specimen onto the sample stage of the nanoindenter and choose the cone and indenter to mount it to the driver of the micro and nano mechanics testing system. Click on the highlighted drive to connect it with the nanoindenter.

After installing the nanoindenter and loading the specimen in the SEM control software, click the vent button. Open the SEM chamber after breaking the vacuum, install the nanoindenter on the SEM sample stage, and connect the wires as shown in the picture. Then open the control software of the nanoindenter, and sequentially select loaded indenter range.

Select experimental protocol. Start controller and init to initiate the sample stage initialization. After initialization, close the SEM chamber and click on the pump button on the SEM control software.

Next, click on the up or down button in the SEM control software to adjust the position of the sample stage along the SEM field of view. Fix the position by clicking the okay button. Turn on the electron gun by selecting the highlighted EHT button.

Switch to the electron microscopy observation mode by selecting the camera button. Finally, click run on the nanoindenter control software. To terminate the experiment, click the stop button on the control software of the nanoindenter.

The system enhanced the experimental scheme design by combining it with the operations, providing instant validation. For example, as the user chose the placement direction of the specimen, the interface for using the metallographic specimen inlaying machine showed the results. Similarly, by analyzing the resulting displacement time and stress strain curves from an inside mechanic's experiment of a micro cantilever beam with present cracks, the user could determine how the results were obtained.

In the simulated scenario, the students had to evaluate the load size and loading time according to the length to diameter ratio of the specimen to be prepared before conducting rheological experiment, instead of the often used trial and error approach. Further, with integrated exercise following the experiments, users could systematically review the entire experiment process and connect the theory with the experimentation. Using the web-based virtual simulation, students on average completed the experiment in about 73 minutes, verifying the efficiency of the approach.

The online exam results of two groups of engineering mechanic students showed that those with the virtual interface experience performed better than those without, further demonstrating the efficiency of the approach. This have teaching students research interest and the sense of innovation by training them to master the testing techniques, method, and principles of advanced micro and nano skill mechanical experiments.