Research On The Deformation Mechanism And Laws Of Thin-walled Abnormal Shell Power Spinning Using 3D FEM

The thin-walled abnormal shells are a kind of very important parts, widely used in aerospace and military industry. Research on the deformation mechanism and deformation laws of the thin-walled abnormal shell power spinning is a key problem urgently to be solved for the research and development of thin-walled abnormal shell spinning. So, in this dissertation, a 3D Elasto-plastic dynamic explicit FEM model of power spinning of thin-walled abnormal shell is established under the ABAQUS/Explicit software environment, then the deformation mechanism and the influencing laws of forming parameters on the process are investigated. A brief introduction to the project and its main results are as follows:At the first, a 3D Elasto-plastic dynamic explicit FEM model of power spinning of thin-walled abnormal shell has been developed. Both computation accuracy and efficiency are taken in account, and some key technologies during the establishing process of the model have been solved, including the determination of initial position of roller and roller path, and the definition of blank thickness which is variable etc. The model has been validated by theoretical evaluation and experimentation comparison. The establishment of the model lays a foundation for the research on the deformation mechanism and the influencing laws of forming parameters on the process.Then, based on the model established above, the distribution and variation features of the stress and strain, the wall thickness during the process of power spinning of the thin-walled abnormal shell have been obtained. In the forming process, the biggest Mises stress and equivalent plastic strain become bigger and bigger;The biggest Mises stress of the blank lies in the place contacting with roller all the time, and the biggest equivalent plastic strain lies in the place contacting with roller in the beginning, then with the forming process, transfers to the behind of the roller;the wall thickness near the part peristome reduces acutely, but for the rest ofthe part, reasonable wall thickness can be obtained. It is found that, at final stage of the process it is easy for an excessive reduction of wall thickness to appear, which is resulting from the metal accumulation appearing at the front of roller due to the cumulative excessive reduction of wall thickness. Thus a method by controlling the local blank thickness or the clearance between roller and mandrel to control the local excessive thickness reduction caused by metal accumulation is proposed.Finally, the influence laws of some important parameters, including radii of roller roundness, roller installation angle, friction coefficient between roller and blank and;feed rate of roller, on the change of the stress and strain, the wall thickness in the power spinning process of the thin-walled abnormal shell have been revealed. The results show that: the decrease of roller roundness radii or roller feed rate, or the increase of friction coefficient between roller and blank or roller installation angle, will make the plastic deformation and the wall thickness distribution more homogeneous, weaken and even eliminate the metal accumulation in front of the roller. These results may provide a guide for the determination and optimization of parameters of power spinning process of thin-walled abnormal shell.