The Measurement And Finite Element Simulation For Deformation Of Structural Component Based On DIC Method

Digital image correlation (DIC) method is a modern method of optical measuring technique, which was developed in early eighties of last century. It has many advantages, such as white light source, full field measurement, simple optical arrangements and big measurement range. Therefore there is a wide application foreground for DIC method. The full field strain can be obtained by DIC measurement, which is significant for analysis of mechanical responses of structural components under various loading. The results of full field strain can provide a direct validation for complex problems, which is very useful to improve the accuracy and reliability of FEA simulation of structural components. In this work, a serious of strain field of structural components were measured by GOM ARAMIS optical measurement system under various loading. Based on measured strain field, relative strain measurement problem and elastic-plastic deformation problem were researched.The following parts are contained in this paper:Part 1. The tensile test of aluminum alloy thin sheet with center-hole was carried out. The full field strain of specimen was measured by DIC method and was simulated by FEA method. The strain filed near center-hole was studied carefully. The difference between DIC measurement and FEA simulation was analyzed. The conclusion can be obtained that the precision of DIC measurement depends on the speckle grid. And the results of DIC method for the stress centralization region will be less than the true strain if the speckle grid is too sparse;Part 2. The monotonic tensile and monotonic compressional tests were carried out for AZ31B magnesium alloy. And the monotonic tensile experiment was performed for 5083 aluminum alloy. Moreover, three-point bending tests were performed for the magnesium alloy and aluminum alloy structural specimens. The FEA simulations of three-point bending were compared with experimental ones. The influence of asymmetry of tension and compression on FEA simulation was studied for magnesium alloy structural component. It is shown that the finite element calculation will be more accurate if different material parameters are used for the tensile and compression region of magnesium alloy component respectively;Part 3. A new method of tension-torsional strain measurement based on digital image of single camera was established for thin-walled tubular specimens of multi-axial experiments. Firstly, four tag lines were marked in the surface of specimen. Then the changes of tag lines were recorded by digital camera during tensional-torsional experiment. Finally, the tensional-torsional strain can be calculated by Matlab program. Additionally, the results of proposed method and results of DIC method were compared for the same tensional-torsional test. It is shown that the axial and torsional strain agree well between two methods.