Study on Electromagnetic Fracture Mechanics of Material Systems for New Electromagnetic Devices

点击翻译按钮获取中文摘要

Design and development of new electromagnetic devices require basic research on electromagnetic fracture mechanics. In this research project, the electromagnetic fracture mechanics of material systems is investigated. From the theoretical considerations and experimental results for electromagnetic material systems, the following can be concluded1) (a) We consider the scattering of time harmonic flexural waves by a through crack in a conducting plate under a uniform magnetic field normal to the crack surface for two special cases, perfect conductivity and quasistatic electromagnetic field, which are of physical interest. The dynamic moment intensity factor versus frequency is computed and the influence of the magnetic field and the angle of incidence on the normalized values is displayed graphically.(b) We discuss the magneto-elastic interactions and singular moments in a soft ferromagnetic plate with a through crack under a uniform magnetic field normal to the plate surface. The static … More and dynamic moment intensity factors are computed and the influence of the magnetic field on the normalized values is displayed graphically.2) We examine the bending of a soft ferromagnetic beam plate in a transverse magnetic field both theoretically and experimentally. The effect of magnetic field on the deflection and strain is shown graphically. A comparison of the deflection and strain is made between theory and experiment, and the agreement is good for the magnetic field considered. We also study the effect of magnetic field on the fracture behavior of a soft ferromagnetic beam plate.3) We consider the cryogenic fracture behavior of structural alloys and weldments for superconductiong fusion magnets in high magnetic fields both analytically and experimentally.4) (a) We consider the static and dynamic problems of cracked piezoelectric materials and composites. Numerical calculations are carried out, and the stress intensity factor, energy release rate and crack growth rate are obtained. We also study the static behavior of the elastic and electric variables in the vicinity of a surface electrode attached to a piezoelectric ceramic.(b) We discuss the scattering of normally incident longitudinal waves by a finite crack in an infinite isotropic dielectric body under a uniform electric field. The dynamic stress intensity factor versus frequency is computed and the influence of the electric field on the normalized values is displayed graphically.5) (a) We perform the bending tests on piezoelectric material systems and examine the piezoelectric effects on the deflection. We also employ the finite element analysis to study the electromechanical behavior of piezoelectric material systems. Numerical results are compared with the experimentally measured response.(b) We carry out the Vickers indentation tests on piezoelectric materials and examine the influence of applied electric field, polarization and load on the fracture toughness. The specimen fracture behavior is also simulated numerically using the finite element technique. Numerical results are provided to illustrate both qualitative and quantitative behavior of the induced electromechanical fields.6) We performe the numerical simulation for analyzing the electromagnetic fracture and deformation of material systems. The predictions obtained from the simulation correlate very well with the experiments. Less