| Nano-indentation technique is a non-destructive testing method,it has been gradually formed due to the micro mechanics,in the process of testing on the test sample without damage,make it become more and more popular.However,due to the blockade of foreign technology and nano-indentation test instrument is expensive,in the past ten years the development of in nano-indentation testing technology has achieved initial success in China.Combined with the stress state of the material in the actual service discovery materials are often subject to the interaction of a variety of loads and materials in the process of stress will generate heat,the temperature will also change,therefore,to design a device for in situ nano-indentation test on prestressed under temperature gradient is important.This paper combines the existing nano-indentation technique of nano-indentation testing device of prestress under temperature gradient of the whole design,by calculating the components on the selection and analysis of displacement and load testing of the unit calibration,then the indentation test device for processing and assembly.The indentation testing device is integrated into the whole machine to avoid interference.Based on the nano-indentation technique theory analysis methods of data analysis and summarize the characteristics of the indentation test device,and then makes a detailed analysis of the key technology of precision drive,precision detection,temperature and loading characteristics of the support unit,the indentation testing device using semi automated control mode,according to the selection process of C language in program control.Looking at the point of manual adjustment,the contact point found after the automatic test process control system data input control.The indentation force sensor with weights respectively and displacement sensor calibration,feedback regulation testing by PID,the original indentation curve end indenter and the specimen after the test test,calibration analysis of the data obtained in this paper frame flexibility test device of the original curve using mapping method,and then repeat the curve test.The displacement of the resolution is 0.1nm,the resolution of loading force is 0.001 m N,the control rate of 1nm/s to 50nm/s and 0.1m N/s to 50 m N/s.The test device can use pre tensile pre fatigue test indentation,indentation test can also test the temperature gradient magnetic field,this paper mainly test indentation pre tensile pre fatigue under temperature gradient.Before the test of specimen size and surface processing and installation of samples and head for detailed examination,the selected samples for titanium alloy TC4 indentation test,it belongs to the type of titanium alloy,with good comprehensive mechanical and mechanical properties.The indentation test temperature of Ni-Ti memory alloy,shape memory alloy is its plastic deformation automatically restore the original shape of the special alloy at a particular temperature.Through the load observation of Ni-Ti shape memory alloy displacement curve,change the mechanical properties of material,the indentation curves under different temperature is found by comparing a slight change,but when the temperature reached 45 degrees indentation changed significantly,found through experiments after data processing,the phase transition temperature,elastic modulus and stiffness remained almost unchanged after reaching the temperature of phase transformation point,due to the elastic deformation of the memory effect of the material,elastic modulus,stiffness increases suddenly. |
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