Transient Response Characteristic Of Magnetic Fluid Saturated Poroelastic Medium

The research on magnetic fluid saturated magnetoporoelasticmedium is very important to geology and geophysics. The analysis of thetransient response characteristic of this medium has great significance tothe magnetoleastic wave spreading in the moist soil and undersea rock.The main research purpose of this paper is to discuss the transientresponse of this medium. The research contents and main founding showbelow:(1) The Maxwell stress of magnetic skeleton and magnetic fluid wasconsidered in the constitutive relations of fluid saturated porousmedium. Based on it, the dynamic equations of magnetic fluidsaturated magnetoporoelastic medium were deduced. Theanalytic solutions of the equations were acquired by integraltransformation. Based on it, transient response of a semi-infiniteconducting magnetic fluid-saturated poroelastic medium with acylindrical cavity on which the axisymmetric excitation isapplied were analyzed based on the above theory. The variationlaw of stress and displacement of skeleton and magnetic fluidwas acquired.(2) The above theory was degenerated as to investigate the influenceof the effect of magnetic pressure on the response which meantthe ignorance of the magnetic pressure in the governingequations. Based on the above theory, the same example wascalculated numerically. By comparing the numerical results，wecan know that the summit values of stress and displacement ofskeleton and magnetic fluid of which the effect of magnetic pressure on skeleton is considered is larger and the time theyreach the summit value is longer than that of not considering theeffect of magnetic pressure on skeleton. The higher the intensityof the external magnetic field is, the more obvious the influenceof magnetic pressure on the response is.(3) When the magnetism of solid skeleton was neglected but theeffects of magnetic pressure on skeleton were considered, thetransient response of the above example was calculatednumerically. By comparing the calculating results, the followingconclusion can be acquired: in the given external magnetic field,the influence law of magnetic skeleton on the summit values oftransient response and the time they reach the summit values isthe same as that of effect of magnetic pressure on skeleton. Theinfluence of magnetism of skeleton on the summit values is lessobvious than that of effects of magnetic pressure on skeleton andhas no influence on the stable values. The effect of magneticskeleton is more obvious as the intensity of external magneticfield increase.