A compact bending device for in-situ three-point bending tests under laser scanning confocal microscope

In-situ testing methods are used to investigate the real-time changing process of materials under different mechanical tests. This paper describes a miniature in-situ three-point bending device, which is compatible with the laser scanning confocal microscope. This device integrates a servo motor, a two-stage worm gears reducer with large reduction ratio and two small lead ball screws. It can realize quasi-static loading mode with a wide rate range from 0.1 µm/s to 0.1 mm/s. The microstructure of the specimen can be observed dynamically during the three-point bending test combined with the force-deflection curve. A calibration method was introduced to calibrate the flexibility of the developed device. The bending experiments were carried out for several different materials with known elastic modulus to verify the feasibility of the calibration method. Finally, the in-situ three-point bending test of red copper was performed to verify the function of the device.