Papers by Keyword: Circular Cavity

Abstract: A theoretical analysis is followed to calculate the dynamic stress intensity factors (DSIFs) in transversely isotropic piezoelectric bi-materials, due to existence of a permeable interfacial crack, near the edge of a circular cavity. The model is subjected to dynamic incident anti-plane shearing (SH-wave) and the formulation based on Green's function method. Conjunction and crack-simulation techniques are applied to obtain DSIFs at the crack’s outer tip. Calculations are prepared based on FORTRAN language program. A comparison is accomplished between the present model and another model with a crack emerging from the cavity edge to calibrate the program. Calculating results showed the influences of the physical parameters, the structural geometry and the wave frequencies on the dimensionless DSIFs and how those affected the efficiency of piezoelectric devices and materials.

Abstract: In transversely isotropic piezoelectric bi-materials, a theoretical analysis is followed to calculate the dynamic stress intensity factors (DSIFs) due to existence of a permeable interfacial crack, near the edge of a circular cavity. The model is subjected to dynamic incident anti-plane shearing (SH-wave) and Green's function method is the base of formulation. Conjunction and crack-simulation techniques are applied to obtain DSIFs at the crack’s inner tip. Calculations are prepared based on FORTRAN language program. For calibration of program, a comparison is accomplished between the present model and another with a crack emerging from the cavity edge. Calculating results clarified the influences of the physical parameters, the structural geometry and the wave frequencies on the dimensionless DSIFs and how those affected the efficiency of piezoelectric devices and materials.

Abstract: Steady state responses of a circular cavity and a semi-circular canyon subjected by plane SH wave in an elastic quarter are presented by using Fourier-Hankel wave function expansion method and image method with Fourier series expansion on the boundary conditions to determine linear algebraic equations of unknown wave function coefficients. Especially, displacement and stress component expressions are formulated for incident, reflected, scattering waves, respectively. This method can provide an analytical ideas and methods for further studies of elastodynamic interface problems.

Abstract: Numerical controlled milling is widely used in the manufacturing industry because of its high productivity and workpiece surface quality. The aim of this work is to establish a methodology to evaluate the rough machining time and to predict optimal values of cutting speed to minimise machining time of circular cavity, during high speed milling. The circular cavity is divided into volumes distributed according to the real radial depth. The obtained results show that the proposed method is consistent with the actual situation.

Abstract: The problem of dynamic response of multiple circular cavities near multiple semi-cylindrical alluvial valleys under incident plane SH-waves is investigated by the methods of complex function and multi-polar coordinates in this paper. Firstly, the solution domain is divided into two parts, Domain I is multiple semi-cylindrical alluvial valleys, and Domain Ⅱ is an elastic half space with several subsurface circular cavities near multiple semi-cylindrical alluvial valleys. A series of infinite algebraic equations is then obtained based on the displacement and stress continuity condition on “common boundary” of two parts after constructing the associated displacement and stresses expressions of each part. Finally some numerical expamples are prensented and dynamic response of subsurface circular cavities near semi-cylindrical alluvial valleys with respect to different parameters is discussed.

Abstract: The analytical solution to the problem of the scattering of SH-wave by isosceles triangular hill near the subsurface cavity in right-angle plane is given by using the idea of match up. Firstly, wave function was constructed by using the methods of complex function, multi-polar coordinate transformation and superposition principle, which satisfied the stress free boundary conditions at the free surfaces for the right-angle plane possessing a circular cavity. Secondly, transform the wave field from the right-angle plane to the half space by using the method of mirror image in order to obtain the total wave filed, which satisfied the boundary conditions. Finally, based on the conditions of the displacement continuity and stress continuity at the “common border” and the stress free condition at the subsurface cavity edge, a series of infinite algebraic equations were given and solved by truncation. Meanwhile, some examples and results are given and discussed.

Abstract: Sacttering of SH-wave of combined deffectiveness which included single circular cavity and double linear cracks in elastic medium was investigated in detail. Analytic solution of this problem was obtained by Green’s Function method and idea of crack-division at actual position of crack at two times. There were two key steps of this method. First step was to employ a special Green’s Function which was a fundamental solution of displacement field for an elastic space with a cavity in it subjected to out-of-plane harmonic line source force at any point at first. The sceond step was crack-division which was artificially to produce a crack by apllying opposite shear stress caused by incident SH-wave. Distribution of dynamic stress concentration factor (DSCF) at edge of cavity was studied by numerical analysis. Distribution Curves of DSCF of three models were plotted by numerical method in polar coordinate system. Three models were one circular cavity and without crack, one circular cavity and single crack and single circular cavity double cracks. The results were compared and discussed in different incident angle of SH-wave.Conclusion was that the interaction among SH-wave, single cavity and double crack was obvious. Dynamic stress concentration factor varied with angle and distance between cavity and crack.

Abstract: In order to solve the thermal deformation of the hydrostatic thrust bearing in the heavy equipment, a simulation research concerning temperature field of multi-pad hydrostatic thrust bearing having circular cavities was described. The Finite Volume Method of Fluent has been used to compute three-dimensional temperature field of gap fluid between the rotation worktable and base. This study theoretically analyzes the influence of cavity radius and cavity depth on the bearing temperature performance according to computational fluid dynamics and lubricating theory. It has revealed its temperature distribution law. The simulation results indicate that an improved characteristic can be gotten from a circular cavity hydrostatic thrust bearing, oil cavity temperature decreases by gradually with cavity radius enhancing, oil cavity temperature decreases by gradually with cavity depth. Through this method, the safety of a hydrostatic thrust bearing having circular cavities multi-pad can be forecasted, and the optimal design of such products can be achieved, so it can provide reasonable data for design and lubrication and experience and thermal deformation computation for hydrostatic thrust bearing in the heavy equipment.