A Study Of Kinetic Effect Of Crack Arrested By Electromagnetic Heating

Crack arrested technology by electromagnetic heating is a new and practicaltechnology developed in recent years. And it has made remarkable achievements intheoretical and experimental research. Based on previous studies, due to the thermaleffects of electromagnetic pulse current, the crack tip will produce apparent "thermalshock" at the instance of discharge, the kinetic effects analysis of inertia term are firstintroduced, solving the equations of thermo-elastic displacement potential with inertiathrough the Laplace transform and Hankel transform, draw relational expression of kineticeffect with time. The results showed that instant heat not only makes the crack tippassivation, but also produce mutated stress in the vicinity of the crack tip. Thecompressive stress effectively curbs the growing of the crack. Through theoretical analysis,numerical simulation and experimental study, kinetics effects of the crack arrested byelectromagnetic heating were analyzed.On the level of theoretical analysis, kinetic effects of unilateral crack and circularburied crack were respectively studied. By using the Laplace transform method, thekinetic effect under steady-state and dynamic-state are respectively calculated, and stresschanges over time of the two cases are also analyzed through specific examples. On thebasic research of unilateral crack and rounded buried crack, the Kinetic effects of circularhollow crack have been studied and the temperature distribution of the circular hollowcrack after a pulse discharge has been analyzed.In the numerical simulation, the heat-electric sequential coupling method of finiteelement software ANSYS has been used. First simulating the temperature distribution ofthe metal components with defects after discharge, then converted into heat-electriccoupling field to simulate the instantaneous thermal stress distribution of a pulse discharge.Finally the numerical results were compared with the theoretical analysis.In research experiments, first prefabricating unilateral fatigue cracks on a fatiguemachine and discharging on the ZL-2pulse discharge device. After the discharge,analyzing the metallurgical structure and hardness of the area near the crack tip. Prepareround buried crack through the stamping, welding and other processes on circular sheet and use the TZ-2H-type ultrasonic flaw detector to analyze the residual stress at the crackdefects before and after the discharge.The Kinetic effects of electromagnetic heat crack arrest of three metal componentswith different forms of cracks have been studied from theoretical analysis, numericalsimulation and experiments. And the results show that in the crack arrest byelectromagnetic heat, the instantaneous stress, induced by Kinetic effects can effectivelycurb the growing of crack.