A rather complete dynamic model with special emphases on nonlinear conicity and creep force and in consideration of random irregularity of rail profile is proposed to simulate the response and investigate the ride quality of railway vehicles. The CP341 vehicle that will soon be used in Taipei Rapid Transit System is considered in particular as the studied role model. Some of the field test data carried out for this type of vehicle are revealed as well and used for the verification of the proposed model. Both simulation and test results show that the resonant frequency of the studied vehicle is in the range of 0.6∼1 Hz, and the one-third octave root-mean-square acceleration curves of the vehicle in all studied cases meet the ride quality criteria set for the mass rapid transit vehicle systems. It is observed that the secondary suspension of the vehicle has the low frequency filtering property and the primary suspension has high frequency characteristics. A poorer ride quality in vertical direction rather than in lateral direction is also confirmed in the study. It is concluded that the proposed model can be used to simulate the dynamic response and evaluate the ride quality of any railway vehicle.

Pullout tests of bone screws have been performed on cadaver bones, animal bones or synthetic bones. These materials have been proven to be poor models from experimental observation, giving results with too much variability or difference. The finite element method was used in this study to evaluate the holding power for bone screws subject to the changes of outer diameter, inner diameter, pitch and radiuses of tip and bottom round corner. The displacement control mode was used in a way that 1 mm displacement was applied on the flatness region of bone screw head and the reaction force was then recorded to simulate the ability of pullout force. Numerical results showed that the patterns of tip corner on the bone screw were a deciding factor on the pullout force of bone screw. This study was significant for establishing a good bone-screw FEM model and suggesting important threaded parameters in selecting or manufacturing a bone screw to increase its holding power.

Parameters of thermohydrodynamic (THD) lubrication are discussed for the laminar and turbulent regimes. The scales of pressure of temperature are analytically obtained, and are used to measure the variations of density and viscosity. Dominant THD parameters are identified by inspecting the practical applications.

The effective length of a piezoelectric cylindrical specimen in strain measurements is determined by considering the stress decay in a cylindrically anisotropic, circular cylinders of piezoelectric materials subjected to 2D surface tractions and prescribed end loads. On the basis of the state space formalism, the problem is studied by means of matrix algebra. The significance of the end effects is evaluated through a characteristic decay length. The study enables us to assess Saint-Venant's principle as applied to piezoelectricity in general and to determine the effective lengths of tensile and torsional specimens of piezoelectric materials in particular.

The flows past a square cylinder in a channel are simulated using the multi-relaxation-time (MRT) model in the parallel lattice Boltzmann BGK method (LBGK). Reynolds numbers of the flow are in the range of 100 ∼ 1,850 with blockage ratio, 1/6, of cylinder height to channel height, in which the single-relaxation-time (SRT) scheme is not able to converge at higher Reynolds numbers. Computed results are compared with those obtained using the SRT scheme where it can converge. In addition, computed Strouhal numbers compare reasonably well with the numerical results of Davis (1984).

An energy-based damage model is proposed and applied to predict the fracture initiation of the sheet metal forming process. The fracture mechanism is investigated through the plastic energy dissipation. The concepts of the damaging work and the fracture energy are proposed for the quantitative description of damage evolution and crack initiation. The developed formulations are implemented into the finite element program ABAQUS to simulate the biaxial stretching of sheet metals and to predict the fracture strains. The material parameter needed in the damage model for fracture prediction is determined by the stress-strain history of the uniaxial tensile test. The forming limits for aluminum alloy sheets under various strain paths are predicted by the present approach and then compared to the measured data quoted from the literatures [1,2]. Good agreements are found between this study and the previous results.

A semi-analytical finite element (SAFE) method is presented for constructing solutions for an arbitrarily loaded cylinder, whose cross-section is general in terms of its shape and the number of distinct, perfectly bonded elastic, rectilinear anisotropic materials. The surface traction and body force loads need to be expressed in a power series of the axial coordinate. Linear three-dimensional theory is used. For a homogeneous isotropic cylinder, it is known as the Almansi-Michell problem, and the SAFE analysis herein is an extension to inhomogeneous, anisotropic bodies. By SAFE, the cross-section is discretized. The displacement field is expressed by interpolation functions over the cross-section and by analytical functions axially. The method herein is an extension of the authors' previous method cylinder with a general cross-section. Herein, the SAFE solution procedure is given and numerical examples will be presented.

The order of stress singularity at a sharp corner of a plate needs to be known before a numerical approach can be taken to determine accurately the stress distribution of a plate with irregular geometry (such as a V-notch) under loading. This work analyzes the order of the stress singularity at a bi-material corner of a thick plate under bending, based on Reddy's third-order shear deformation plate theory. An eigenfunction expansion technique is used to derive the asymptotic displacement field in the vicinity of the sharp corner by solving the equilibrium equations in terms of displacement functions. This paper explicitly shows the first known characteristic equations for determining the order of the stress singularity at the interface corner of a bonded dissimilar isotropic plate. Moreover, the numerical results are given in graphic form for the order of stress singularity at the interface corner in bonded dissimilar isotropic plates and at the vertex of a bi-material wedge with free radial edges. The results presented herein fill some of the gaps in the literature

A method for investigating the pure squeeze action in an isothermal elastohydrodynamically lubrication (EHL) problem, i.e., circular contacts lubricated with couple stress fluid, was developed. A constant load condition was used in the calculations. The initial conditions such as pressure profiles, normal squeeze velocities, and film shapes were obtained from the classical hydrodynamic lubrication theory at a specified large central film thickness. The coupled transient modified Reynolds, elasticity deformation, and load equilibrium equations are solved simultaneously. The simulation results reveal that the effect of the couple stress is equivalent to enhancing the lubricant viscosity, thus enlarging the film thickness. The effect of couple stress in thin film lubrication varies with film size. That is, the thinner the lubricating film is, the more obvious the effect of couple stress is. For larger characteristic length, materials parameter, and load, the central pressure, central film thickness, and rigid separation are larger than those of smaller characteristic length under the same load. The time needed to achieve maximum central pressure and the Hertzian pressure increases with increasing characteristic length.