Elastic deformation of the rotating functionally graded annular disk with rigid casing

An accurate solution for a rotating functionally graded annular disk is presented. Material properties of the present annular disk are assumed to be graded in the radial direction according to a simple exponential-law distribution. The inner surface of the disk is pure metal whereas the outer surface of the disk is pure ceramic. The boundary condition of rigid casing is considered herein, that is the vanishing of the radial displacement at the outer surface. The boundary condition at the inner surface of the disk is taken to be vanishing either radial displacement or radial stress. Analytical solutions for the elastic deformation of the rotating functionally graded annular disks subjected to these boundary conditions are obtained. Numerical results for radial displacement, circumferential and radial stresses are presented. Comparisons between the different rotating homogeneous and functionally graded annular disks are made at the same angular velocity. The results show that distributions of stresses and displacement through the radial direction of the rotating annular disk vary with different parameters.     

The torsion of a microelastic half-space by a flat annular rigid stamp

The present paper seeks to solve the problem of an elastic half space under torsion by a flat annular rigid stamp in the linear micropolar elasticity. The problem is reduced to the solution of a system of four Fredholm integral equations of the second kind in four unknown functions. An iterative solution of these integral equations has been obtained for $\text{λ = a/b ? 1}$ for the case of simple rotation through a small angle $\text{ω}{}_0$ and the corresponding classical results have been obtained.     

On the axisymmetric loading of an annular crack by a disk inclusion

This paper examines the axisymmetric elastostatic problem related to the loading of an annular crack by a rigid disk–shaped inclusion subjected to a central force. The integral equations associated with the resulting mixed–boundary–value problem are solved numerically to determine the load–displacement result for the rigid inclusion and the Mode II stress–intensity factors at the boundaries of the annular crack. The results presented are applicable to a wide range of Poisson's ratios ranging from zero to one half.     

An elastic contact problem for a half-space indented by a flat annular rigid stamp

We consider an elastic contact problem for a half-space indented by a flat annular rigid stamp, which is a three-part mixed boundary value problem. If the distribution of pressure on the contact region is assumed, the contact problem will be reduced to the solution of an infinite set of simultaneous equations. Numerical results are also illustrated for the distributions of the displacements and stresses in the half-space.     

Acoustic diffraction by two concentric coaxial soft spherical caps

Summary The subject of this paper is the problem of diffraction of a time-harmonic axially symmetric acoustic wave by two concentric coaxial soft spherical caps. An integral equation technique is employed to solve such a boundary value problem involving two concentric coaxial spherical caps. Approximate expressions are derived for the far field amplitude as well as the scattering cross section for this problem when the incident wave is a low frequency axially symmetric plane wave travelling along the common axis of the two caps. By taking appropriate limits, the formulae for scattering cross section for the corresponding problems for a soft spherical cap, a soft sphere and a soft sphere bounded by a concentric soft spherical cap are also derived. Furthermore, the total electrostatic charge required to raise the two concentric coaxial spherical caps to unit potentials in a free space is readily evaluated from the analysis of this paper.     

An elastic contact problem for a neo-hookean half-space indented by a annular rigid stamp of arbitrary profiles

The present paper deals with an elastic contact problem for a neo-Hookean half-space indented by a annular rigid stamp of arbitrary profile, which constitutes a three part mixed boundary value problem. The problem is reduced into triple integral equations which are further reduced into an infinite set of simultaneous equations. Numerical results are illustrated graphically for the distributions of the normal displacement and stress in the case of parabolic concave punch for different values of a/b at $\text{z = 0}$     

A transversely isotropic half-space indented by a flat annular rigid stamp in the presence of adhesion

Conclusions The curves of normal displacementu _z (r, 0) (Fig. 2) in the presence of adhesion coincide approximately with the dashed line. The contact pressure zz(r,0) in the presence of adhesion is slightly larger than the one without friction. Thus,u z(r,0) and zz(r,0) in the actual condition can be evaluated approximately by the results without friction.With 3 Figures     

Vector diffraction analysis of optical disk readout

The optical disk readout signals from ROM disks are presented by use of a rigorous three-dimensional vector diffraction method. The optical disk is modeled as a crossed metal grating without restriction on the form of the information marks, and the permittivity of the metal is taken into account. The diffracted field from the disk is obtained by means of decomposing the focused incident beam into a spectrum of plane waves and then calculating the diffracted plane waves for each respective incident component. The readout signal is obtained by integration of the energy-flux density of the diffracted field according to the detection scheme of the optical disk system. A typical digital versatile disk (DVD) system is applied with this theory, and the result is far from that of scalar diffraction theory.     

Reverse field orientation effects on rigid disk coating

A reverse magnetic field usually exists for orienting electromagnets used to align particles in magnetic media. Disk disorientation caused by this reverse field, known as the "dorf effect", was found to be a strong function of coating rheology, actual process steps, and reverse field magnitude. Experiments were done on 8-inch and 14-inch rigid disks with coatings of different viscosity varying the most sensitive orientation process parameter, spin-off time. In addition, more controlled experiments were done using 1/2-inch-diameter hand-coated aluminum disks exposed in the gap of an electromagnet to an orienting field followed by varying magnitudes of disorienting fields. Finally, a modified orientation electromagnet with a reduced reverse field was constructed. Our conclusions are that reverse field magnitudes, required to produce significant disorientation are strong functions of coating viscosity, coating formulation, and spin-off times. A 100 Oe reverse field creates a disorienting problem only when using very short spin-off times for coatings of low viscosity, containing a significant portion of high boiling point solvents. Reverse fields larger than 200 Oe, resulting from either high orienting current or a particular electromagnet design, will cause serious disorientation for most magnetic coatings.     

Design issues for practical rigid disk magnetoresistive heads

Some of the issues of magnetoresistive (MR) head design are discussed from the point of view of practical, high-reliability, low-cost, manufacturable heads for rigid disk files. The major advantages of MR heads over single element inductive thin-film heads are that the MR head gives an ideal, easy to equalize output waveshape, can be used on disks with high coercivities for high linear densities, and is less subject to stability problems at narrow trackwidths. The major advantages of MR heads over metal-in-gap ferrite heads are in narrow trackwidth and high-frequency potential. Disadvantages of MR heads in the rigid disk environment include concerns about reliability and, more specifically, possible environmental fragility, loss of performance due to imperfect alignment between the read and write elements and/or due to signal asymmetry, and the possibility of higher cost/price     

Acoustic wave passing through moving rigid screen

Abstract

A rigorous boundary condition for a linear acoustic wave passing through a moving rigid screen is derived from a modified theory of poroelasticity in this paper. The governing equation of the acoustic wave in the air passing through moving rigid screens. The boundary condition is found to be more general than that applied in earlier works done by the first author and his coworkers.

tion is found to be more general than that applied in earlier works done by the first author and his coworkers.     

旋转柔性圆盘的气-固耦合振动

研究了旋转柔性圆盘与周围气膜之间的耦合振动问题.首先给出了基于润滑理论考虑了柔性圆盘振动影响的气膜压力分布的Reynolds方程,以及考虑了盘的旋转离心力、弯曲刚度和气膜压力影响的旋转柔性圆盘的运动方程,然后用有限元对气膜压力方程及旋转柔性圆盘的运动方程进行了离散化,用数值方法求解了旋转柔性圆盘运动与气膜压力的耦合方程,研究了旋转柔性圆盘的气-固耦合振动特性,讨论了周向静载荷的大小、载荷施加位置和气膜厚度对旋转柔性圆盘振动响应的影响.结果表明,周向静载荷的位置对旋转柔性圆盘的振动有很大的影响.一般情况下,周向静载荷越靠近盘的外缘,柔性盘的振动就越大;气膜越厚,柔性盘的振动越大.     

Elastic-plastic annular disk with variable thickness subjected to external pressure

Summary The plane state of stress in an elastic-plastic annular disk with variable thickness under external pressure is studied. The thicknessh is assumed to vary along the radius in the formh=h ₀(r/b)^–n . The analysis is based on Tresca's yeld condition, its associated flow rule and linear strain hardening.