The Development And Research On The Reliability Of Micron Scale Indentation Instrument

Instrumented indentation methods as an important way to characterize the mechanical properties of smaller-specimen materials,it can effectively measure the mechanical properties of materials,such as elastic modulus,hardness and creep.Compared with the traditional testing methods,it has the outstanding advantages of nondestructive testing and saving the test cost,which is helpful for the development of surface engineering,microelectronics,integrated micro-opto-electro-mechanical system,biological engineering and medical materials and other fields.In order to make up for the shortcomings of traditional testing methods of macro and micro mechanical properties,instrumented indentation methods proposed and improved by many scholars has gradually become one of the most commonly used testing methods in the field of material mechanical properties.Based on the characteristics of current instrumented indentation methods and indentation instruments,it formulates the design goal of the large stroke micron scale indentation instrument.Besides,it completes the relevant work,such as the design of instrument structure,the analysis of key components and overall structure of the instrument,the debugging and calibration of instrument,the design and development of measurement and control software,etc.Finally,it carries out the reliability research for the indentation test of typical materials based on the instrument.The main contents are as follows:(1)Based on the commonly used driving technologies and detection technologies in the indentation instruments,it completes the type selection of driving and detecting components in micron scale indentation instrument based on the requirements of design.The step motor is selected as the driving type of the indentation instrument,and the load sensor of strain gauge and the displacement sensor of grating are selected as the detection type of the instrument.According to the commonly used Berkovich indenter,Vickers indenter and conical indenter in the indentation test,the theoretical explanation is based on the classic Oliver-Pharr indentation test method.(2)It carries out the design of the whole structure of the micron scale indentation testing device,which also conducts the modal analysis of the whole structure and key components of the instrument to verify the stability of the structure.From the analysis results,it shows that the resonance frequency of the key components and the whole testing device designed in this thesis are higher than that of the conventional test,so the structure of the instrument is reasonable and stable.Then,it designs and develops the measurement and control software of the indentation test system according to the components and functional attributes of the whole test system.(3)According to the micron scale indentation test system built,it carries out the test calibration for the load and moving displacement sensors,which also calibrates the frame flexibility of the instrument,and systematically analyzes various factors affecting the indentation test.Then,it conducts the test for the linearity of objective table,closed-loop control and test repeatability of indentation instrument.Finally,it carries out the reliability research for the three typical materials of 7075 aluminum,single crystal tungsten and standard Vickers hardness block based on the micron scale indentation.