Development Of An In-situ Tensile And Fatigue Testing Instrument Based On A New Type Of Piezoelectric Actuator

Materials Technology is the foundation of the national economy and theforerunner of all high-tech. It is one of the important causes of leading majoraccidents and the loss of lives and property that the material failure caused by theuncertainty of the microscopic mechanism of the material damage. In situ tensile andfatigue testing are considered as one of most typical static and dynamic technologiesto visually supervise the micro deformation, damage and structures changes ofmaterials. The microstructure observation and mechanical properties can be achievedby in-situ test. Comparative analysis of the material microstructure changes in the testand the mechanical properties curve contributes to in-depth study of the material. Onthe basis of a comprehensive analysis of material microstructure mechanicalproperties testing technology development status, this paper develops the in situtensile and fatigue testing instrument based on a new type of piezoelectric actuator.Firstly, it proposes a novel clamping principle-by self-locking of the clampingblocks. With this clamping principle, two new piezoelectric actuators are developed.Secondly, a set of test system is established and the performances of the piezoelectricactuators are tested. The experimental results show that the two piezoelectric actuatorssuitable for the in-situ tensile and fatigue testing instrument. Thirdly, with newpiezoelectric actuator, an in-situ tensile and fatigue testing equipment is designed andits design process and working principle are introduced. The closed-loop system isestablished to eliminate errors. Fourthly, the performances of the in situ tensile andfatigue testing instrument are tested by a set of established test system. Finally, thein-situ tensile and fatigue testing equipment is used in conjunction with a microscopeto test the mechanical properties of copper materials.The testing instrument proposedin this paper has the following innovations: (1)The proposed piezoelectric actuators utilize self-locking effect to clamp themover and have greater carrying capacities.(2) The in situ tensile and fatigue testing instrument uses the new piezoelectricactuators and has a more accurate test result and a higher movement resolution.(3) The in situ tensile and fatigue testing instrument has a suitable overall sizeand a better compatibility with the microscope and other imaging equipment.The experimental results show that the proposed in-situ tensile and fatiguetesting equipment has a reasonable structure, a novel working principle and highprecision. It is reliable and can be achieved the in situ tensile and fatigue tests of thebulk materials.