A theoretical method is presented,which analyzes properties of surface acoustic waves propagating on metallic gratings with finite thickness by combining finite element method with variational principle on surface aco...A theoretical method is presented,which analyzes properties of surface acoustic waves propagating on metallic gratings with finite thickness by combining finite element method with variational principle on surface acoustic waves propagating on periodic metal gratings. Based on D.P.Chen and Haus theory,a finite element method is used to investigate the effects of metallic gratings upon the propagation of surface acoustic waves.The coupling-of-modes parameters contributed by mechanical loading are expressed by the matrix derived from the finite element method.Consequently D.P.Chen and Haus theory can also be applied to analyze the properties of surface acoustic waves propagating on metallic gratings with finite thickness and arbitrary shape.Finally,the characteristics of surface acoustic waves propagating under gold and aluminum or silver gratings on a few piezoelectric crystals are studied.Numerical results of the coupling-of-modes parameters of the surface acoustic waves are obtained.展开更多
Shear bands in the interior of Pd（79）Cu6Si（10）P5,Pd（79）Cu3Ag3Si（10）P5, and Pd（79）Cu4Au2Si（10）P5 bulk metallic glasses were investigated by optical microscopy（OM） and scanning electron microscopy（SEM）. ...Shear bands in the interior of Pd（79）Cu6Si（10）P5,Pd（79）Cu3Ag3Si（10）P5, and Pd（79）Cu4Au2Si（10）P5 bulk metallic glasses were investigated by optical microscopy（OM） and scanning electron microscopy（SEM）. No shear bands can be observed in the samples before etching. By etching in aqua regia solution, shear bands are found to be susceptible to preferential etching, and multiple etched bands could be observed. The thickness of the etched bands is about 1-7 μm. Therefore, the preferentially etched shear bands found in the study are called the ＂extended＂ shear bands.The ＂extended＂ shear bands can be divided into three classes according to their features： early, developing, and well-developed ＂extended＂ shear bands with thickness of about 1, 5, and 7 μm, respectively. The interface between the well-developed ＂extended＂ shear bands and the matrix is clearer than that of the others.展开更多
基金supported by the National Nature Science Foundation of China(10974171)Zhejiang Province Nature Science Foundation(LY12A04003)
文摘A theoretical method is presented,which analyzes properties of surface acoustic waves propagating on metallic gratings with finite thickness by combining finite element method with variational principle on surface acoustic waves propagating on periodic metal gratings. Based on D.P.Chen and Haus theory,a finite element method is used to investigate the effects of metallic gratings upon the propagation of surface acoustic waves.The coupling-of-modes parameters contributed by mechanical loading are expressed by the matrix derived from the finite element method.Consequently D.P.Chen and Haus theory can also be applied to analyze the properties of surface acoustic waves propagating on metallic gratings with finite thickness and arbitrary shape.Finally,the characteristics of surface acoustic waves propagating under gold and aluminum or silver gratings on a few piezoelectric crystals are studied.Numerical results of the coupling-of-modes parameters of the surface acoustic waves are obtained.
基金financially supported by the National Natural Science Foundation of China (Nos. 51101133 and 51101134)the Encouraging Foundation for Outstanding Youth Scientists of Shandong Province, China (No. BS2012CL036)the Shandong Provincial Natural Science Foundation, China (No. ZR2011EL025)
文摘Shear bands in the interior of Pd（79）Cu6Si（10）P5,Pd（79）Cu3Ag3Si（10）P5, and Pd（79）Cu4Au2Si（10）P5 bulk metallic glasses were investigated by optical microscopy（OM） and scanning electron microscopy（SEM）. No shear bands can be observed in the samples before etching. By etching in aqua regia solution, shear bands are found to be susceptible to preferential etching, and multiple etched bands could be observed. The thickness of the etched bands is about 1-7 μm. Therefore, the preferentially etched shear bands found in the study are called the ＂extended＂ shear bands.The ＂extended＂ shear bands can be divided into three classes according to their features： early, developing, and well-developed ＂extended＂ shear bands with thickness of about 1, 5, and 7 μm, respectively. The interface between the well-developed ＂extended＂ shear bands and the matrix is clearer than that of the others.
