Research On The Wave Characteristics Of FGM Prepared By Hot Pressing Sintering

With the development and technology progress of the aerospace and military industry, various special materials’ performances have been required. There is an expectation that materials have the excellent synthetical performance while having some special performances. But the traditional single material and homogeneous material are hardly satisfied with these special requirements. However, functionally graded materials（FGM） can meet the requirements in high-tech field. With the increasing application of large structures in industry, the high-effective and convenient detection method is required urgently. Because of the convenient application characteristic of guided wave now it is the hotspot in the field of ultrasonic guided wave.SiO₂/Fe FGM have the advantages of high temperature resisitance, high specific modulus, high hardness and good match, for online detection, which is under the high temperature difference circumstance, it has the important research and application value. In this paper, based on the traditional preparation process, SiO₂/Fe FGM with component changing continuously is prepared by hot-pressing sintering method. Then, it’s density and size are measured. Furthermore, FGM’s microstructure and it’s component are observed and analysed by using super depth digital microscope system and scanning electron microscope respectively. An innovative method of preparing FGPM by non-pressure infiltration is proposed and described detailedly in this paper.In this paper, based on the “Mechanics of Incremental Deformations”, the propagation of SH waves in FGM plates under initial stress are investigated; The viscoelastic circumferential SH wave in graded hollow cylinders are investigated based on Kelvin-Voigt viscoelasticity; Apply a double orthogonal polynomial series method to investigate the guided wave propagation in a two-dimensional（2-D） structure innovatively, namely, a FGM ring with a rectangular cross-section. The numerical results show that the effects of the initial stress in the thickness direction are very different from those in the wave propagating direction, both on the dispersion curves and on the stress shapes; the influences of gradient profile and the influences of the radius to thickness ratio on dispersion and attenuation are illustrated; and the dispersion curves and displacement distributions of various FGM rings, which have different radius to thickness ratios, different material gradient directions and different thickness to height ratios, are calculated to reveal the guided wave characteristics.