Theoretical Analysis, Applied Exploration And Optimal Design Of Hole Electromagnetic Strengthening System

Compared to the traditional hole strengthening technology, electromagnetic strengthening method has no harm to the material surface, insensitivity to the pattern and aperture of hole, simple adjustment control, easy to strengthen the sheet and other unique advantages, so it has broad prospects for research.The fundamental principle of hole electromagnetic strengthening method is to generate circumferential inductive current and axial background magnetic field in the region of workpiece with hole by electromagnetic induction. When inductive current and background magnetic field develop to a certain high level, the radial pulsed electromagnetic force in the workpiece with hole will cases the margin of hole to yield plastically and deform in a very short time, finally a residual compressive stress layer is introduced which could improve the fatigue life of the workpiece of hole.Firstly, the principle, basic structure and related realization methods of hole electromagnetic strengthening system is elaborated in detail in this paper, and the reason for using after-flow loops in the internal and external circuit is explained too. Then the finite element numerical calculation model of hole electromagnetic strengthening system including two-dimensional and three-dimensional models is successfully established, which consider the circuit, electromagnetic field, structure field and temperature field. The following chapters build the elastic-plastic mechanical model based on the plain strain model, analyze the change of stressful state of the workpiece with hole, study the distribution of residual stress from the respect of stress-strain behavior, explore the time-delays of the internal and external coil to the strengthening effects. Later, the applicable ranges of hole-edge distance and hole interval in hole electromagnetic strengthening system is discussed. Finally, the design of hole electromagnetic strengthening system is optimized in the basis of prototype system, the results show that the optimized necessary energy and temperature rise of coil is decreased significantly, which verifies the effectiveness of the optimization methods proposed.