Application And Analysis Of Non-Contact Measurement Technology In The Deformation Of Aviation Metal Material

Deformation is a basic mechanical property of engineering materials. Therefore, the study about the process and mechanism of deformation damage of aircraft materials has the important practical significance. Strain gauges and extensometers are often used to measure deformations but inefficiently, and they will directly touch objects and cause damage. Vic-3D(Video Image Correlate-3D)No-contact Mearement System, as a new method to measure deformations, is getting more and more attention, because of its high efficiency and accuracy without contacting objects, nor damage. However, this method have not been used in domestic civil aviation. In this thesis, I will use this method to research the deformation of metal material of civil aviation- 2024 to lay the foundation for civil aviation applications.In this thesis, there are static tensile tests on 2024 aluminum alloy flat samples by using the Instron Electronic Universal Testing Machine, and Vic-3D takes all the information about deformation. Firstly, optimize the speckle quality parameters and image acquisition system parameters. Secondly, take points on both sides of the crack flat sample without holes to study the propagation of crack. Thirdly, study the influnce of holes with different areas and different ratios between the long axis and short axis on mechanical properties, then take the points along the radius direction to study local strain. Fourthly, compare the methods of Vic-3D, extensometers and Patran. Finally, use electron scanning microscopy to analyze the micro-fracture of samples.Research indicates,the major factors affecting the speckle quality and optimal results are speckle radius(0.02in),speckle density(50%),speckle randomness(69%).The major factors affecting the image acquisition system and the best results are??(59 pixels),step(12pixels),angle between cameras(20°~25°),aperture(5.6~8).By comparing strain and strain rate of data points on both sides of the crack,we can determine the crack source and the corresponding parts of the load to predict the failure.The more close the sample hole position,the strain are more concentrated.Reducing the sample aperture area and ratio between the long and short axis can effectively reduce the strain concentration factor of the sample.Comparing three test methods,Vic-3D system can not only record the tensile strain of the whole process,but reflect the real situation with more advantages.The facture has a lot of dimples,which contain aluminum-copper alloy hard particles.All cracks appeared in the inside holes,and near the surface of the sample,there are fast tear marks.