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Sodium bismuth titanate (Bi0.5Na0.5TiO3, BNT) has attracted much attention because of its excellent dielectric, piezoelectric and electromechanical properties. The microstructure of sodium bismuth titanate-doped ferrum niobium material (Bi0.5Na0.5TiO3 doped (Fe0.5Nb0.5)4+, BNT-xFN) shows a triangle as its typical defect shape. Since piezoelectric devices usually operate under dynamic loads, they fail easily owing to dynamic stress concentration or dynamic fracture. Elastic waves can simulate many types of dynamic loads, and the dynamic stress concentration caused by an anti-plane shear wave is the basis for the calculation of the stress field strength factor of type Ⅲ-dynamic fractures. In this study, the electroelastic coupled-wave diffraction and dynamic stress concentration of BNT-xFN materials with triangular defects under the incidence of anti-plane shear waves were studied. Maxwell equations are decoupled by auxiliary functions, and the analytical solutions of the elastic wave field and electric field are obtained. Based on the conformal mapping method, the triangle defect was mapped to the unit circle defect, and the dynamic stress concentration coefficient around the triangle defect was obtained by calculating the undetermined mode coefficients in the expression through boundary conditions. The numerical calculation shows that the size of the triangular hole, the frequency of the applied mechanical load, the incidence angle of mechanical load and the amount of FN doping have a great influence on the stress concentration of BNT-xFN materials.

Based on the theory of magnetoacoustic coupled dynamics, the purpose of this paper is to evaluate the dynamic stress concentration near an elliptical opening in exponential-gradient piezomagnetic materials under the action of antiplane shear waves. By the wave function expansion, the solutions for the acoustic wave fields and magnetic fields can be obtained. Stress analysis is performed by the complex function method and the conformal mapping method, which are used to solve the boundary conditions problem, and is used to express the dynamic stress concentration coefficient (DSCC) theoretically. As cases, numerical results of DSCCs are plotted and discussed with different incident wave numbers and material parameters by numerical simulation. Compared with circular openings, elliptical openings are widely used in material processing techniques and are more difficult to solve. Numerical results show that the dynamic stress concentration coefficient at the elliptical opening is strongly dependent on various parameters, which indicates that the elliptical opening is more likely to cause crack and damage to exponential-gradient piezomagnetic materials.

Based on the magnetoacoustic coupled dynamics theory, the wave function expansion method is used to solve the problem of acoustic wave scattering and dynamic stress concentration around the two openings in e-type piezomagnetic composites. To deal with the multiple scattering between openings, the local coordinate method is introduced. The general analytical solution to the problem and the expression of the dynamic stress concentration are derived. As an example, the numerical results of the dynamic stress distribution around two openings with equal diameters are given. The effects of the parameters, such as the incident wave number and the spacing between the openings, on the dynamic stress concentration factor are analyzed.

Background: Diminished Ovarian Reserve (DOR) is a common disease in reproductive-age women in the diagnosis and treatment of infertility. The incidence of DOR increased quickly in recent years and had became one of the most important factors that made the quality of women life decline. Gynecology and reproductive medicine professors have made great efforts to explore good treatment methods all over the world. Traditional Chinese Medicine has made some achievement in treating DOR as a kind of complementary and alternative therapy In Vitro Fertilization (IVF) in recent years, it is indispensable to propose a network meta-analysis (NMA) protocol to discuss the efficacy and safety of TCM in IVF. Methods: A literature search will be conducted in 8 electronic databases. Results: The efficacy and safety of traditional Chinese medicine in preconditioning patients with diminished ovarian reserve that would undergo In Vitro Fertilization will be evaluated. Results: The systematic review will evaluate the efficacy and safety of TCM in IVF. Conclusion: The result of this study will provide reliable evidence of the use of TCM in IVF. INPLASY registration number: INPLASY2020110062. Ethics and dissemination: This review does not require ethical approval.

Composite SiNx/DLC films were deposited on Si substrate by RF magnetron sputtering of silicon nitride (Si3N4) target simultaneously with filtered cathode arc (FCA) of graphite. The RF power was fixed at 100 W whereas the arc currents of FCA were 20, 40, 60 and 80 A. The effects of arc current on the structure, surface roughness, density and mechanical properties of SiNx/DLC films were investigated. The results show that the arc current in the studied range has effect on the structure, surface roughness, density and mechanical properties of composite SiNx/DLC films. The composite SiNx/DLC films show the sp3 content between 53.5% and 66.7%, density between 2.54 and2.98 g/cm3, stress between 1.7 and 2.2 GPa, and hardness between 35 and 51 GPa. Furthermore, it was found that the density, stress and hardness correlate linearly with the sp3 content for composite SiNx/DLC films.

This part of the paper is aimed at the development of models for the drill tip’s transverse and angular motions, the definition of models for establishing the drilled hole’s profile and, by combining these results with the dynamic force models of Part 1, the formulation of the complete model for drill skidding and wandering. An experimental verification of the models concludes the paper. For the development of the drill motion models the drill is simplified as a pretwisted beam subjected to a compressive axial load and radial forces acting on its tip. The governing equations are developed using Hamilton’s principle. Subsequently, the weak form of the governing equation is formulated to facilitate their solution by the finite element method. The corresponding boundary conditions for the motion model are also defined for three drilling phase, i.e., drill skidding, drill wandering and stabilized drilling. Based on the drill tip’s wandering locus and drill rotation, a mathematical model for describing the drilled hole’s profile is developed.

This two-part paper is aimed at developing a theoretical and numerical simulation basis for initial penetration phenomena that profoundly influence hole tolerances and shape. In Part 1, dynamic force models are developed followed by models of the drill’s dynamic behavior in Part 2. Next, these models are combined and used to predict initial penetration behavior and hole shape. A comparison of simulated and experimental results concludes Part 2. In this part, by considering the effects of drill grinding errors and drill deflections, dynamic cutting chip thickness models are developed which, in combination with workpiece surface inclination effects, allow the formulation of expressions for the dynamic chip thickness and cutting chip cross-sectional area. By using these quantities to replace their static counterparts, static drilling force models are extended to facilitate the prediction of dynamic cutting forces. Separate thrust, torque, and radial force models for the major cutting edges, secondary cutting edge, and for the indentation zone are formulated. The effects of drill installation errors on the radial cutting forces acting on the chisel edge and the major cutting edges are also included.

By considering the effects of drill grinding errors and drill deflections, dynamic cutting chip thickness models were developed which in combination with workpiece surface inclination effects allowed the formulation of expressions for the dynamic cutting chip cross-sectional area. By using the dynamic chip thickness and dynamic cutting chip area to replace their static counterparts, static drilling force models were extended to facilitate the prediction of dynamic cutting forces in micro-drilling processes. The geometric characteristics of micro-drills were considered in these mechanistic force models. Separate thrust, torque and radial force models for the major cutting edges, secondary cutting edge and for the indentation zone were developed. The effects of drill installation errors on the radial cutting forces acting on the chisel edge and the major cutting edges were also included.

SiN x and diamond-like carbon (DLC) films were prepared simultaneously on Si substrates by the RF magnetron sputtering of a silicon nitride (Si3N4) target and the filtered cathodic arc (FCA) deposition of graphite, respectively. The RF power was fixed at 100 W, while the arc current of graphite for the FCA deposition was varied from 20 to 80 A. The structure of composite SiN x /DLC films was investigated by Raman spectroscopy. The chemical composition and chemical state of the films were analyzed by X-ray photoelectron spectroscopy (XPS). Results revealed that the atomic concentration of carbon (C) increased, while those of silicon (Si) and nitrogen (N) decreased with increasing arc current. In addition, the sp3 content in the composite films was found to increase with the arc current. This result indicates that the structure and property of the composite films can be controlled according to their required applications by varying the arc current.