Using an electroplated nickel, a fundamental research for measurement of cyclic stresses in high temperature range is carried out. The plating used consists of two layers, namely, a preliminary deposit of alkaline copper in a copper cyanide bath and a nickel deposit in a sulfamate bath. The plating conditions suitable for the present purpose are proposed. In the high temperature range from 125°C to 200°C, crystal grains of deposited nickel are developed by cyclic stresses above a certain magnitude. Consequently, micro-flecks occur on the surface of deposits depending on the magnitude of applied cyclic stresses. The stress concentration factors in grooved shafts under bending are obtained at 160°C and 180°C. The results are compared with the theoretical and experimental results obtained previously.

View full abstract

A finite element formulation without any sophisticated tensor calculus is given for the elastoplastic problem of large strains and large displacements. The concept of natural stresses and strains is applied to the formulation in order to make the large strain theory more easily understandable for the engineers who are unaccustomed to the tensor calculus. A few examples of plane problems are computed and the results obtained are discussed, whereby the appropriateness and the applicabilities of the proposed theory are demonstrated.

View full abstract

Various mechanical quantities and conservation equations of dynamics can be arranged in good order by means of appropriate infinitesimal operators. In dynamics of point mass systems, the infinitesimal operators of translation and rotation can yield various dynamical quantities from the energy form, and the corresponding conservation equations from the energy conservation equation which form a family tree. Dynamics of a rigid body is also considered from the view-point of infinitesimal operators. The technique is useful in studying dynamics of continua with microstructures.

View full abstract

The characteristics of a rotary flow dust collector for the dust separation process in connection with the flow pattern of air, pressure drop, total collection efficiency and the fractional collection efficiency η_x are made clear. The test dust is fly-ash which has mean diameter x_RSO =12.44 μm. Then the mechanically balancing particles x^^-_PB which make a statistically stationary rotation in the collector are determined experimentally. And from the relationship between x^^-_PB and η_x, the separation process of the dusts in the collector is investigated. Experimental equation of η_x is written as follows : η_x =1 -exp{(-1n2)(x/x_CSO)^m} where x is particle size and x_CSO is a cut-size corresponding to x of η_x = 0.5 (50%). The exponents m of the separation are compared with the other types of cyclone, and m with x_CSO is an index which shows the separation efficiency. And the results of experiments show that the collector can more easily attain a high collection efficiency than the ordinary type of cyclone.

View full abstract

To investigate the fluid force acting on a body oscillating with a finite amplitude in a fluid extending to the infinite space, the authors present a brief theory based on the virtual mass of the fluid taking account of the phase difference between the motion of the body and that of the virtual mass. The experiments mainly made on oscillating discs have shown fair agreement with the theory, and given the following findings : (1) The variation of the fluid force occurs in sinusoidal form just as predicted by the theory. (2) The magnitude of the force is proportional to S^<1.8D³w², where S is stroke, D diameter, and w circular frequency. (3) The phase difference is almost stationary in the range between 30 and 40 degrees, being insensitive to S, D and w. (4) The virtual mass increases with S/D, amounting to 3.7 times the value for the inviscid fluid when S/D is unity.

View full abstract

The roles of the lateral oscillation of a pipe in the coupled vibrations of pipes with oil in hydraulic circuits are receiving attention. The vibrations are theoretically analyzed under the assumption that the pulsation of oil and the longitudinal and lateral oscillations of a pipe are coupled at pipe ends alone and have no interactions elsewhere. Solid viscosity is introduced into the dynamics of a pipe wall as previously to explain the damping of pipe oscillations. The pipe oscillation in the lateral direction is mathematically represented by several equations of bending vibration of a beam. The vibration experiments are run in the unrestrained L-shaped and T-shaped lines with fixed terminals, and characteristic resonant phenomena of bending and branching lines are observed. The experimental results reveal the significant roles of the lateral pipe motion and the feasibility of the analytical procedure developed here.

View full abstract

In this second report, we investigate the relation between the turbulent diffusion of a bubble and eddy diffusivity of heat in the core of a fully developed pipe flow. As a result, it is found that the diffusivity of bubbles is smaller than the eddy diffusivity of heat, and can be divided into three regions, corresponding to the distribution of terminal velocities of bubbles in water against the size of bubbles.

View full abstract

The light-intensity distributions of turbulent premixed burner flames for various turbulence intensities were derived from the photometric density distributions on direct photographs, assuming that the flames were axially symmetrical. Based on the obtained light-intensity distributions, the structure of a turbulent premixed flame and the influence of turbulence intensity on it were quantitatively discussed. The turbulent flame-zone thickness was confirmed to increase with the distance from the burner port, and its increasing rate was shown to increase with the turbulence intensity. The maximum probability density of the flame front at a given cross section of the flame zone was found to decrease with increasing the distance from the burner port and to approach an almost constant value. In the region where the maximum value was constant, the probability density of the flame front as well as the turbulent flame-zone thickness was found to increase with the turbulence intensity.

View full abstract

An experimental investigation is made of the tangential displacement and the energy dissipating properties at solid interfaces under various contact pressures and the lubricated or the nonlubricated condition. A tangential microslip and an elastic displacement due to contact asperities between a ground and a sandblasted mild steel surface and between two sandblasted mild steel surfaces are measured. The behaviours of the oil films and the deformed asperities during a tangential displacement are examined by measuring an electric contact resistance. The results presented show that the tangential microslip and the elastic displacement due to contact asperities are smaller for two sandblasted surfaces than for a ground on a sandblasted surface. The tangential microslip, the elastic displacement, and the area within a hysteresis loop in the process of unloading and reloading are largely affected by the apparent contact pressures, the oil films, and the preloads.

View full abstract

Variational formulation is derived for the steady state compressible Reynolds equation under slip-flow conditions. Finite element techniques and a numerical procedure, using Newton-Raphson iteration method to solve the non-linear finite element equations, are described. These techniques are applied to conventional slider bearings and the effects of the molecular mean free path (MMFP) for a wide range of the compressibility numbers (Λ= 1∼10⁴) are shown. Then, MMFP effects for different bearing configurations are compared. As a result, it is found that non-dimensional load W is useful for estimating MMFP effects. The load or velocity versus spacing characteristics are calculated for a cylindrical slider bearing. These calculations reveal that when spacing decreases with velocity fro a constant load, MMFP effects increase monotonously. However, when spacing decreases with tan increase in load at a constant velocity, MMFP effects only increase slightly. The new calculation procedure developed here has wide applicabilities, converges rapidly and saves computer memory.

View full abstract

It is a purpose of this paper to clarify the behavior of grease lubrication between two cylinders under heavy loads. The hydrodynamic equation of a Bingham solid and the elasticity equation are solved simultaneously by a simplified method to discuss how the core formation in a Bingham flow affects the film thickness and the pressure of the elasto-hydrodynamic lubrication. The pressure dependencies of a plastic viscosity and a yield stress are included in this analysis and their effects are also discussed. It is found that the larger yield stress produces the larger film thickness under a certain load and velocity, and that the pressure dependence of plastic viscosity rather than that of a yield stress affects the film thickness largely. The experiments are carried out to compare with the analytical results.

View full abstract

The authors studied experimentally the influence of the transmitted tooth load on the dynamic increment load and others about a sngle-stage Stoeckicht planetary gear (Type 2K-H) constructed with spur gears. The results are as follows : (i) The influence of the eccentricity of lower speed shaft and higher speed shaft can be sufficiently eliminated by using a floated sun gear. (ii) When the natural frequency of a planetary gear coincides with any order of the mesh-frequency, the tooth load varies largely and the momentary load distribution is reduced to inequality. (iii) When the transmitted tooth load becomes small, the dynamic load and the additional torque increase remarkably.

View full abstract

Two types of bolted joints are used to connect the column and the base of a machine tool. In this paper, the bending stiffness and the debase of a machine tool. In this paper, the bending stiffness and the deformation mechanism of the above types of bolted joints subjected to a static bending load are described ; here the thickness of the clamped portion of the experimental model is taken as a parameter. New, general characteristics of the bending stiffness are dependent on the deformation mechanism of a bolted joint. Large localized deformation is generated around bolts and at the boundary portion between the column and its flange. The bending stiffness of a column with a bolted joint used in radial drilling machines takes a maximum value, so called an optimum thickness, when the ratio of flange thickness to bolt diameter is nearly equal to 2.0.

View full abstract

Peen forming has been utilized in the special field of the airplane industry. The authors conceive independently the principle of this process and intend to develop this as a general forming process of sheet metals. Suitable selection of peening conditions such as the diameter or the velocity of a shot enables bulging of a disc and bending of a strip. Successful conditions in these formings depend on the peening energy of a grain of shot and there exist a lower and an upper limit of the energy. When the upper limit is exceeded, the disc sinks and the strip bends in the opposite direction. So, the intended forming cannot be attained. Peening brings about a strengthening through work-handening and a roughening of the products. This process is applied successfully to strong brittle materials which are difficult to form because it has a feature of forming under compressive stresses.

View full abstract