The Experimental Research And Numerical Simulation On Off-plane Displacement Of The Inclusions

In this paper, the vertical displacement field of hard aluminum inclusions, voids inclusions in the tensile loads was measured using electronic speckle pattern interferometry, its test results-digital images were processed with Matlab language. And using the ANSYS finite element analysis software for mechanical simulation of its displacement field and strain field,the results have been consistent unanimous conclusion comparing with the experiments. It lays a certain foundation to study the basic law of the damage propagation of inclusions and provide some theoretical basis and guiding role for application from the experiments and mechanical simulation analysis.The specific content of this study are:(1) the appropriate choice of electronic speckle experimental optical path measuring the vertical displacement, hard aluminum inclusions and voids inclusions were measured in the gradual tensile load. (2) It processes a digital speckle pattern interferometry fringe image with the MATLAB language, processing methods include histogram equalization, gamma adjustment, median filtering, exponential low-pass filter, Butterworth low-pass filtering and binarization.It analyzes and summarizes the stripes trends of the inclusions, in the tensile load. (3) It simulates and analyzes mechanically displacement field, stress field, strain field of hard aluminum inclusions and voids inclusions under tensile load using ANS YS finite element software, and electronic speckle pattern interferometry experimental results were compared, has been consistent, consistent and reasonable results.Through the study of the paper obtained the following conclusions:1. Using Butterworth low-pass filter for speckle interferometry image filtering processing, can improve the contrast of speckle interference fringes, are conducive to inter-stage stripes discrimination and interpretation.2. The upper and lower ends of hard inclusions is the first location of the dark stripes initiation, that is the upper and lower ends of hard inclusions is the location of maximum displacement or strain. As the load capacity increases, the upper and lower ends as the center of stripes and gradually expand to the left/right position of hard inclusions, the number of stripes increase gradually; location of the upper and lower ends are the weak areas, if the load exceeds the linear elastic range, the first micro-cracks created here, and then crack expand to the left/right position; while empty inclusions are the contrary.3. ANSYS mechanical simulation of the physical model, using sub-region meshing method can improve the computer's calculation speed; electronic speckle pattern interferometry fringes related to qualitative analysis of the situation can be used under the z-plane stress model to carry out the strain field simulation analysis; relative to the solid model, selected under the plane stress model of the empty inclusions on tensile specimen obtained more accurate simulation, a simple strain, stress distribution.4.ESPI fringe pattern and the finite element numerical simulation of the displacement contour map representation of the hard inclusion and hole deformation around the inclusions in the shape and distribution of the match, proved the experiment, image processing and finite element numerical simulation method of reasonable and correct.5. Numerical simulation results show that when the tensile load along the y direction, the upper and lower ends of the hard inclusions for high displacement zone, high strain and high stress zone, while the area around both ends for low-displacement, low-strain zone, low-stress areas; empty a mixture of the case is just the opposite. ESPI fringes is always first in the location of the greatest stress initiation, and then spread to the low-stress zone. Maximum stress position is weak areas, will be the first to produce micro-cracks.