Direction Of Thrust Force Research Articles

Probabilistic pile reinforced slope stability analysis using load transfer factor considering anisotropy of soil cohesion

AbstractA probabilistic limit equilibrium framework combining empirical load transfer factor and anisotropy of soil cohesion is developed to conduct pile‐reinforced slope reliability analysis. The anisotropy of soil cohesion is determined conditioned on that the thrust force direction is parallel to the major principal direction and it is easily combined with load transfer factor, which are related with soil parameters, and pile parameters. The proposed method is illustrated against a homogeneous soil slope. The sensitivity studies of pile parameters on factor of safety (FS; calculated at respective means of soil parameters) and β demonstrated that the anisotropy of soil cohesion tends to pose significant effect on reliability index β than on FS. The effect of anisotropy of soil cohesion on FS is found to be slightly different under different pile locations, whereas its effect on β is observed to be least if piles are drilled at the middle part of slope and more significant effect is observed when piles are drilled at the lower and upper part of slope. The plots from the sensitivity studies provide an alternative tool for pile designs aiming at the target reliability index β. The proposed method contributes to the pile‐reinforced slope stability within limit equilibrium framework.

Numerical study to evaluate the important parameters affecting the hydrodynamic performance of manta ray's in flapping motion

Manta ray swimming or bio-inspiration propulsion system, as a special type of marine propulsion system, is used for submersible vehicles that require high-speed maneuverability and stability, such as glider and AUV. In a manta ray swimming, the thrust force is generated by a couple of undulation and oscillation of wing, so that the direction of undulation wave and oscillation is upright and perpendicular to the direction of thrust force, respectively. It is possible to combine these two movement modes (flapping motion) on the three-dimensional model without considering the effects of wing twisting and flexibility to simplify and better understand the physical behaviors or special study of this movement on the manta rays as a marine glider. This study uses the computational fluid dynamics (CFD) tool to numerically simulate the complex unsteady vortical structure of flow due to the manta ray's flapping motion. The incompressible Navier-Stokes equations are solved using a pressure-based finite-volume method. In this research, the effect of kinematic parameters such as Strouhal number, non-dimensional heaving amplitude (h*), the maximum angle of attack (α0), the oscillation velocity on hydrodynamic performance during flapping motion is studied by applying a couple of heaving and pitching movement on manta ray mid-section (2D) and manta ray model (3D). The results show that although both thrust production and power consumption values are low in the 3D model, they attain higher efficiency than the 2D model.

Finite element method for stress analysis in the frame holder of generator translation and rotation motion on vertical direction mechanism for sea wave power plant

Finite element method (FEM) has been used to calculate stress analysis in many field of engineering or industry (metal, automotive, power plant and etc.). FEM can be applied to reduce cost of product processing before manufacturing process. Requirement of design of product is cheaper, good properties, effective and efficient depend on function of product. Stress analysis depend on the properties of material, load, static and dynamic and shape of product or component. In the metal processing, FEM is applied for stress analysis in the conveying roll component due to the load on the roll and thermal stress analysis in the component of low pressure die casting machine. In the power plant, FEM is applied in the frame holder of generator to get stress due to static and dynamic load. Requirement properties of material frame holder of generator is stable, high strength, high stiffness, high corrosion resistance, and etc. In this research focus on the stress in the frame holder of generator translation and rotation motion on vertical direction. Varying load and material has been used for frame holder of generator such as cast iron, stainless steel, steel and thermoplastic resin. In the previous study, frame holder of generator has been used from cast iron and thrust force direction come from horizontal direction. The results get the maximum value (σmax) of von mises of generator is is 643.4 MPa and the deflection value is 6.13 mm. By applied of vertical thrust force direction on the frame holder of generator translation and rotation is found that the maximum stress von misses value σvmis 74845 MPa and displacement is 17.9 mmby load 10 KN and using cast iron to frame holder of generator material.

Surface damage reduction of dry milling carbon fiber reinforced plastic/polymer using left–right edge milling tool

Carbon fiber reinforced plastic/polymer is popular for aerospace structures and these structures require milling with desired configuration and integrity within strict damage tolerance. However, due to the influence of cutting thrust force on the surface materials when milling carbon fiber reinforced plastic/polymer, it is easy to cause surface damages. This article aimed to study the effect of cutting thrust force direction and size on the damages and guided the suitable milling tool and cutting parameters, further to propose a milling method with low damages. The two-dimensional cutting model was established successfully for analyzing the tool–composite contact and the fiber–plastic/polymer interface crack. Based on the model, the cutting direction forward inside and small cutting force are the ways to avoiding the burrs and tears. The thrust force was the main concentrated force causing the damages in milling, so the left–right edge milling tool was proposed to realize cutting fibers to inside for both surfaces. Besides, small feed per tooth is an effective way to reduce the force. Therefore, the left–right edge milling tool with small feed per tooth is low-damages method. Comparative milling experiments are carried out to verify the method, from the result, the burrs, tears and delamination are effectively inhibited.

Numerical analysis on effects of blade number on hydrodynamic performance of low-pitch marine cycloidal propeller

Marine cycloidal propeller, as a special type of marine propulsion system, is used for ships that require high maneuverability, such as tugs and ferries. In a marine cycloidal propeller, the thrust force is generated by rotation of a circular disk with a number of lifting blades fitted on the periphery of the disk, so that the propeller axis of rotation is perpendicular to the direction of thrust force. Each blade pitches about its own axis, and the thrust magnitude and direction can be adjusted by controlling the pitching angle of the blades. Therefore, the propulsion and maneuvering units are combined together and no separate rudder is needed to maneuver the ship. Two configurations of marine cycloidal propeller have been studied and developed based on propeller pitch: low-pitch propeller (designed for advance coefficient less than one, means λ < 1) and high-pitch propeller (designed for λ > 1). Low-pitch marine cycloidal propellers are used in applications with low-speed maneuvering requirements, such as tugboats and minesweepers. In this study, the effects of blade number on hydrodynamic performance of low-pitch marine cycloidal propeller with pure cycloidal motion of the blades are investigated. The turbulent flow around marine cycloidal propeller is solved using a 2.5D numerical method based on unsteady Reynolds-averaged Navier–Stokes equations with shear-stress transport k–ω turbulent model. The presented numerical method was validated against experimental data and showed good agreement. The results showed that the thrust coefficient of marine cycloidal propeller generally decreases by increasing the blade number, whereas the torque coefficient increases. Consequently, the hydrodynamic efficiency of marine cycloidal propeller drops as the blade number increases.

A 2.5D numerical study on open water hydrodynamic performance of a Voith-Schneider propeller

Marine cycloidal propeller (MCP) is a special type of marine propulsors that provides high maneuverability for marine vessels. In a MCP, the propeller axis of rotation is perpendicular to the direction of thrust force. It consists of a number of lifting blade. Each blade rotates about the propeller axis and simultaneously pitches about its own axis. The magnitude and direction of thrust force can be adjusted by controlling the propeller pitch. Voith-Schneider propeller (VSP) is a low-pitch MCP with pure cycloidal blade motion allowing fast, accurate, and stepless control of thrust magnitude and direction. Generally, low-pitch cycloidal propellers are used in applications with low speed maneuvering requirements, such as tugboats, minesweepers, etc. In this study, a 2.5D numerical method based on unsteady RANS equations with SSTk-ωturbulent model was implemented to predict the open water hydrodynamic performance of a VSP for different propeller pitches and blade thicknesses. The numerical method was validated against the experimental data before applying to VSP. The results showed that maximum open water efficiency of a VSP is enhanced by increasing the propeller pitch. Furthermore, the effect of blade thickness on open water efficiency is different at various advance coefficients, so that the maximum efficiency produced by the VSP decreases with increasing blade thickness at different propeller pitches.

超音波振動切削に関する研究（第１報）―背分力方向振動切削機構の基礎的解析と実験的考察―

The final objective of this investigation is an invention of theory and technics for multiple precision cylindrical machining with combining ultrasonic vibration cutting on thrust force direction, and superposition superfinishing process. This finishing process is a high efficient mirror machining providing (20-50Hz) low frequent vibration and ultrasonic vibration above 20 kHz to fine abrasive stone. In this report, ultrasonic vibration cutting mechanism on thrust force direction is analyzed and it is shown that high precision machining can be achieved by using the effect of insensitive vibration cutting mechanism. And cutting phenomenon are observed by some experiments. In the results, it is confirmed that chips on low feed rate and high cutting speed conditions have been cut to pieces as same as analyzing, and that work displacement on vibration turning can be reduced according to growing up tool amplitude. This report indicates that ultrasonic vibration cutting on thrust force direction can be possibly used for multiple precision cylindrical machining.

On the prediction of chip flow angle in non-free oblique machining

A new method for predicting the chip flow angle of inserts with different cutting conditions was studied in non-free oblique machining process. The effects of the major cutting edge, minor cutting edge, corner radius and cutting parameters (depth of cut and feed rate) on the chip flow direction were studied by calculating the components of the thrust cutting force for the major and minor cutting edges based on the hypothesis that the chip flow direction is also the thrust force direction. This method was verified by comparing the calculated and experimental results with the single-point and nose-radiused cutting edge for different cutting conditions. The prediction results under different cutting parameters show good agreement with experimental data.

Suppression of chatter vibration of boring tools using impact dampers

In this study, improvement of the damping capability of boring tools and suppression of chatter vibration were attempted using impact dampers. Bending tests, impact tests and cutting tests were carried out, whilst widely varying the method of applying an impact damper to a boring tool. The effects of the amount of free mass and clearance, the overhang length of boring tools and their cutting condition were investigated. As a result, the following points were clarified. (i) The damping capability of boring tools is considerably improved using impact dampers. (ii) All three types of impact dampers used in the experiment can considerably suppress the vibration of boring tools in the vertical direction (principal force direction), but hardly suppress it in the horizontal direction (thrust force direction) where the amplitude is extremely small. (iii) In practical use, the method of equipping an impact damper on the flank face of a boring tool is desirable. (iv) Using an impact damper, it is possible to bore deeper holes in comparison with boring tools now on the market and to improve the efficiency of boring operations.

Detection of Tool Wear Using Characteristic Values of Dynamic Cutting Process. 1st Report. Study of Characteristic Values to Detect Flank Wear.

The purpose of this study is to propose new characteristic values of dynamic cutting process to detect tool flank wear during steady cutting in turning. The characteristic values of dynamic cutting process are evaluated by in-process measurement of dynamic cutting force and vibration of a workpiece. In proposed approach, the standard deviation of dynamic cutting force normalized by the standard deviation of undeformed chip thickness and the cross-correlation coefficient between dynamic cutting force and undeformed chip thickness are investigated as characteristic values of dynamic cutting Process to detect flank wear. Furthermore, relation between dynamic cutting force and workpiece vibration in thrust force direction is also investigated by the same way as the relation between dynamic cutting force and undeformed chip thickness. Experiments were carried out on a lathe in orthogonal cutting with a cutting-off tool and a disk workpiece made by a brass plate. As a result of the experiments and considerations, the following characteristic values Iinearly change with increase of flank wear due to nonlinearlity of dynamic cutting process caused by flank wear. (i) The standard deviation of dynamic thrust force normalized by the standard deviation of undeformed chip thickness increases. (ii) The cross-correlation coefficient between dynamic thrust force and undeformed chip thickness decreases. (iii) The standard deviation of dynamic force normalized by the standard deviation of workpiece vibration in thrust force direction increases.

Detection of Regenerative Chatter Vibrations of Turning Workpiece.

In this paper, we propose a new method of detecting regenerative chatter of turning workpiece by using spectrum of vibration of the workpiece. Characteristics of vibrations of the workpiece during cutting was investigated first, and then algorithm of detection was thought out from the investigated results. In this algorithm, it was assumed that regenerative chatter had occurred when the following conditions were satisfied in progress of cutting. (1) Frequency at the peak of spectrum obtained every revolution was almost constant while the workpiece made three revolutions.(2) The amplitude of vibration in thrust force direction was larger than surface undulation of the workiece when the condition (1) was satisfied. Validity of this method was found by several cutting tests on which cutting speed and width of cut were varied in orthogonal cutting. Furthermore, it was shown that regenerative chatter of turning workpiece could be detected also by using spectrum of dynamic cutting force or acceleration of cutting tool.

Dynamic characteristics of a workpiece at cutting. 1st report On vibration in the direction of thrust force.

The frequency characteristics of the workpiece at cutting on the lathe were investigated using the impulse technique. The natural frequencies and damping ratios of the workpiece at cutting were greater than those at no cutting. The damping ratios decreased with an increase in the cutting speed. The estimated natural frequencies, which were calculated from data of the static cutting experiments, were smaller than those of the dynamic experiments, and the estimated damping ratios larger than those of the dynamic experiments. The reason for decrement in the frequencies and increment in the damping ratios was considerd to be the difference of the shear angle between the static and dynamic conditions. The dynamic shear angle was smaller than the static one. The cutting process was expressed in the first order system which became the lead or lag factor.