Multifunctional In-Situ Testing Device for Investigating the Service Performance of Materials.

To obtain the change rule of material/structure service performance under complex working conditions, this study developed a material/structure mechanical property testing device with multiload and multiphysics loading functions. The features of this device include its ability to realize the composite mechanical loading of three loads (tension/compression, bending, and torsion), as well as physical field loading, such as current field, magnetic field, and thermal field, to realistically simulate the actual service conditions of materials/structures. To monitor the surface topography change, temperature, and strain distribution of the specimen in real time, various in-situ monitoring methods, including microscopic imaging, infrared thermal imaging, and digital image correlation method, were integrated into the device. To realize multiload composite loading, a six-degree-of-freedom parallel drive platform was adopted in the device, and its control system was developed with a distributed double-layer structure to realize the closed-loop control of any combination of load forms. All functional modules of the device were calibrated, and a coaxial calibration method based on a 6-D force sensor was proposed. Lastly, several tests were performed to evaluate the effectiveness of the proposed device functions, and the test results revealed the broad application prospects of the device.