The natures of fatigue crack growth under Mode Ⅱ loading are studied. End notched flexure beam specimens were used. The effects of adherend thickness, rubber modification and adhesive thickness on fatigue crack growth were examined. The experimental results show that some of these parameters apparently do affect fatigue crack growth. Resistance to ModeⅡ fatigue crack growth are increased by rubber modification. The effects of adhesive thickness and rubber content on fatigue crack growth were explained by von Mises's equivalent stress using BEM analysis. For unmodified epoxy adhesives, the fatigue crack growth properties under Mode Ⅱ loadings were significantly different in all regions. For rubber-modified epoxy adhesives, they were also different in the first and second regions, but in the third region, they were similar
Various motors have been used in many cars to control the height of automotive seats. As the motor is connected with seat, it can be moved as the convenience of passenger and vibration affects passenger when motor is being driven. In this study, three models are designed. The lengths of link parts and screw axes are increased or decreased respectively in the order of models 1, 2 and 3. The case of motor is made of aluminum alloy and the rest is made of structural steel. As model 1 has the maximum amplitude displacement at 1360Hz by the basis of vibration analysis, model 1 has the most durability among three models. This study result can be effectively utilized with the design on height motor by investigating prevention and durability against its damage.
This paper proposes an information maximization method to extract useful informations for streaming signals. The information maximization method is to extract signals using stream partitioning function and standard normalization function. The stream partitioning function divides streaming signals into intervals. Signal coefficient and interval coefficient are used at generating a interval by using stream partitioning function. Signal coefficient determines the quantity of data included in a signal interval. Interval coefficient determines the starting point of a signal interval. The standard normalization function determines a signal range by using the probability density function for streaming signals. The information maximization method becomes resistant to outliers and missing values. A normal signal can be extracted effectively for streaming signals by the Information maximization method. The effectiveness of proposed method are also presented by several experimental results.
The purpose of this study is to decrease a stress shielding effect shown in the hip joint. To conduct this study, the clad materials were produced by using an explosion welding method with two materials that were different in the elastic modulus like Ti-6Al-4V alloy and pure Ti. As for the clad materials, the Ti-6Al-4V alloy with large elastic modulus was designed as the neck of femur, and the pure Ti with small elastic modulus as the body of femur. The joints of clad materials formed by the explosion welding showed the typical wave shape, and its thickness was about 0.2㎛. New crystal or grain structure was not formed in the joints. In addition, the Vickers hardness in the joints formed the middle value between the base metal and clad metal. As a result of manufacturing prototype by processing the clad materials in three dimensions, this study gained good shape, and if it is to be applied to clinical in the future, this researcher can expect good results. From the result of this research above, it may be summed up as follows. It is considered as the stress shielding phenomenon showed on the hip joint can be decreased to a certain degree if this researcher is to utilize two clad materials with different elastic modulus like Ti-6Al-4V alloy and pure Ti
A 2D axisymmetric numerical analysis was performed to study the characteristics of charge process inside solar thermal storage tank. The porosity and heat transfer coefficient of filler material as well as inlet velocity of heat transfer fluid are selected as simulation parameters. The porosity is varied as 0.2, 0.5, and 0.8 to account for the effect of filler granule geometry. Two levels of the heat transfer coefficient is adopted to assess the heat transfer between heat transfer fluid and filler material. The inlet velocity is varied as 0.00278, 0.0278, and 0.278m/s. As both of the porosity and the heat transfer coefficient increase, the discrepancy of the temperature distributions between the filler and heat transfer fluid decreases. As the inlet velocity increases, the penetration depth of the heat transfer fluid increases proportionally.
Ultra-thin liquid films on solid substrates in contact with the saturated vapor are studied by using molecular dynamics simulation. The properties of evaporation and condensation of the films of various adsorptive strengths and thicknesses are obtained during the quasi-steady film evolution. Net condensations occur when the ultra-thin films on the high energy surface come into contact with the saturated vapor phase because the normal film pressure stays lower than the saturated vapor pressure. The net condensation rate is higher for the material combination of higher adsorptive strength. It becomes more so when the film thickness is of a lesser size. On the other hand, that of lower adsorptive strength has lower net condensation rate and depends less on the film thickness. Therefore, the size effect of the condensation phenomenon is more significant for the system of a higher adsorptive strength. This properties come from the state of ultra-thin film, which can be quantified by using disjoining pressure in the quasi-steady processes. These results have implications in practical problems concerning the moving contact line when the precursor film formation is critica
The development of machining technology has coincided with the recent development of a diverse amount of materials and tools. The developed materials largely consist of hardened steel for vehicle and the mechanical industry. The machining of the hardened steel is performed in a lathe and many kind of machining centers, but it is difficult to machine because its hardness is the most difficult-to-cut materials. Hard-turning is a kind of machining process which omits the final grinding process and replaces it with a single accurate cutting process. In this paper, the turning of SKD 11(HRC 58) was performed using the CBN tool in order to recognize the optimum process conditions. The cutting force, tool life and wear, surface roughness were measured. Examining the machining characteristics when cutting of high hardened steel, low cutting speed and high conveying speed were identified to be effective in cutting conditions of SKD 11. Tool life was most effective in the conditions with 65m/min of cutting speed and 0.193mm/rev of feedrate and approximately 0.5um of very good surface profile was acquired at 0.079mm/rev of feedrate. Therefore, when cutting with Low CBN tool, it could be considered to be sufficient in reducing the steps of precision machining or replacing the polishing
A numerical analysis was performed to study PEMFC performance characteristics depending on the flow direction of cathode reactant gas, cathode relative humidity, and porosity of gas diffusion layer. As cathode relative humidity decreases and porosity increases, current density increases due to better diffusion of reactant gas to cathode surface. As current density increases, power density increases initially and then decreases with its maximum located around current density value of 2.2 Amperes per square centimeter. From the analysis of current density distribution inside membrane, the counter-flow cases show more uniform profile across the membrane than the co-flow cases due to more uniform reactant gas supply.
The thermodynamic state variables in superheated region of steam table are not wholy obtained by measurements. This means that steam table contains a little error. In this study small error was artificially added to superheated variables and modeled using neural networks. The results were compared with the analysis using quadratic spline interpolation method. By and large the relative errors of variables by neural networks were sufficiently small and similar to or less than those by quadratic spline interpolation method. It was concluded that neural networks could be one good way of modeling for superheated steam table.
In the present study, numerical algorithms for a very large crude oil carrier(300K VLCC) were taken into account. The potential flow analysis method was adopted to predict the flow pattern and the fluid force around a ship. The exact nonlinear free surface boundary condition were compared to predict the wave system generated by the ship and the trim and sinkage state of the ship also were considered. In order to deal with complex geometries of the 300K VLCC the panel cutting method was adopted to generate the ship surface panel and the variable free surface panel method was taken applied to generate the free surface panel. The developed numerical analysis algorithm were applied to the 300K VLCC and the results predicted by the numerical analysis were compared with the experimental data
In this paper, a commercial multibody dynamics program ADAMS was utilized to investigate the model for the multi-joint boom conflicts. In this process, CATIA, ANSYS and ADAMS were used to develop the simulation. The addition of ADAMS made the system more accurate and improved precision of the system. In brief, the 3D CAD model of the structure was initially developed via CATIA. After this, the CATIA models were exported to ANSYS for creating flexible-body modeling by using formatted file. Subsequently, with ADAMS, the flexible body model was directly imported from ANSYS which performed the analyses of the dynamic collision of the nozzle boom conflicts. This contained the information regarding geometry and model shapes of the flexible body. Using ADAMS/Durability, it was possible to determine the strain energy for the nozzle configuration by crashing the contact structure that was created. Via this procedure, the acquired simulation analysis of nozzle showed interestingly good results with respect to the objectives of the study
If information representativeness is given to an information network, users can easily see what representative information the site has, and it helps in reducing unnecessary time during information search. This paper proposes the generating representative information method which utilizes the degree of coupling of information and the weighted information value in order to solve various problems which occur in the information network. The generating representative information method measures the degree of coupling of the information by utilizing the attribute information and page information expressed on the information network and generates the representative information by calculating the weighted information value of the information network. are also presented.
In this paper, numerical simulations are performed for the drying process of potato chip in a microwave oven with multiple waveguides, with the purpose of enhancing the uniformity in temperature distribution. A simulation model is built and simulated using COMSOL Multiphysics software. The simulation model uses 5 different positions of waveguides to see whether it affects the heat distribution in the material. In order to know the final temperature result of the material after it comes out of the cavity on a moving conveyor belt, the average temperature values along the direction of the conveyor belt motion are calculated and plotted. From the results, the best waveguide position is determined to get the best temperature distribution in the potato chips.
In the paper an efficient numerical algorithm to predict the flow phenomena around the water-jet propulsion system was described. The potential-based flow analysis method was adopted to predict the velocity and the pressure on the inlet duct of the water-jet propulsion system. The method employed normal dipoles and source distributed on the solid surface such as the inlet duct and the tracked vehicle. The inlet duct and outlet open boundary surfaces were introduced where the sources and dipoles were distributed to define a closed boundary surface. The developed numerical algorithm was applied to a tracked vehicle propelled by the water-jet propulsion system with the different IVR(inlet velocity ratio). The results by the numerical analysis were compared with the experimental data in order to verify the feasibility of the proposed numerical algorithm.
For more efficient air-conditioning in large scaled vessels, structure of air inlet room and location of supply fan are very important. In this study, we have modeled an air intake room of large scaled vessels and tried to examine surrounding flow characteristics around supply fan by a numerical simulation using computational fluid dynamics based on three dimensional steady-state Navier-Stokes equation and standard k-ε model. A commercial CFD program, FLUENT, is used on the analysis. Finally, the analysis showed that the supply fan should be located at the inner side rather than outer side of air intake room, which was original design
This paper carried out a comparative analysis with papers on the analysis and analytic research of conventional solenoid. In case the current of solenoid valve is cut off, a flow path is formed from pressure port (Pc) connected with the crankcase of compressor to Ps port. At this time, the size of Pc port hole was so adjusted (Type-2) that it was smaller than 4.0mm(Type-1) of original hole by 0.2mm. After that, it was thought that an effect would be produced on the flow change of refrigerant which came into the solenoid vale, therefore the flow characteristics in moving from Pc port to Ps port was predicted and comparatively analyzed. According to the results of flow analysis, a velocity of approximately 46m/s and 129m/s was shown at the maximum in case of 0.2 and 1.5 MPa in Type-1, and the maximum velocity of approximately 500m/s and 1400m/s was shown in case of Type-2.
The object of this paper is to evaluate a working environment noise at manufacturing process of metal material products. To accomplish the object; An employee noise exposure criteria, which is mounted in big size enterprise, was investigated. The noise at the 460 points of the manufacturing process machine in the 38 processes of the 1 factories were measured. The database of the noise was built from the measurement data. The major sound sources and frequency range for the manufacturing process of metal material product machine was investigated. In this study, we compare working environment noise criteria of korean with employee noise exposure criteria
In this paper, we analyzed the characteristics of the mass flow rate and velocity of the refrigerant in response to a change in the number of holes and the diameter size(Type-1～4) of the valve guide refrigerant to flow from Pc to Ps when the pressure is constant. Type-1 is 40% higher mass flow flowing in the direction of Ps as compared with the Pc mass flow rate. Type-2 is 64% higher mass flow flowing in the direction of Ps as compared with the Pc mass flow rate. Type-3 is 50% higher mass flow flowing in the direction of Ps as compared with the Pc mass flow rate. Type-4 is 47% higher mass flow flowing in the direction of Ps as compared with the Pc mass flow rate.
The flow between two rotating concentric cylinders, also known as Taylor-Couette flow system, is one of the most widely studied systems in the classical fluid dynamics. In this work, a two-dimensional Taylor-Couette flow system is simulated using the lattice Boltzmann method combined with the smoothed profile method. The fluid flow between the rotating cylinders is solved by lattice Boltzmann equation while the curved boundaries of the cylinders are treated with a smoothed profile function. To assess the validity of the present simulation technique, three different cases of rotation of the cylinders were considered: ⅰ) inner cylinder is only rotating, ⅱ) outer cylinder is only rotating, and ⅲ) both inner and outer cylinders are rotating. For all the three cases, the numerical results of the flow velocity in azimuthal direction and the hydrodynamic torque acting on the cylinders are in good agreement with the corresponding analytical solution results.
Generally, in the previous researches, it is found that a water droplet is respectively in Wenzel and Cassie-Baxter states on hydrophilic/hydrophobic rough surfaces. And Wenzel and Cassie-Baxter equations are used to estimate the apparent contact angle on the surfaces. However, difference between measured apparent contact angle and estimated apparent contact angle with the equations is recently reported and new model to estimate apparent contact angle on rough surfaces is proposed. In this study, wetting state and apparent contact angle on the surfaces with micro-pillars should be investigated to find solution of this argument. Using the high resolution microscope, the wetting state of the D.I.water droplet on the surface with micro-pillars was visualized and apparent contact angle of the D.I.water droplet was measured. On the basis of experimental data, the equations to estimate apparent contact angle were verificated and the general wetting characteristics on the surfaces with micro-pillars are finally classified.