The purpose of this study is to improve the mechanical properties of spread carbon fiber (SCF)/epoxy (EP) laminates containing microcapsules. Finite element analysis (FEA) was employed to evaluate the elastic properties of the SCF/EP laminates. The three-dimensional representative volume element (RVE) models were generated by using Digimat-FE software. The well-dispersion model considers the homogeneous distributed microcapsules in the SCF/EP laminates and the aggregation model presents the aggregation of microcapsules in the SCF/EP laminates. The FEA results demonstrated that the shear modulus obtained from the well-dispersion model was higher than that obtained from the aggregation model. The well dispersion of microcapsules leads to improvement in the elastic properties of the SCF/EP laminates.
Generally, lead is added to brass to obtain free-cutting. However, since lead is designated as a specific harmful substance, brass has been replaced with lead-free brass. In addition, new lead-free brass using additives has been developed to improve the machinability of brass as lead free. This material has already been confirmed to have machinability in turning and milling processing. However, small-diameter drilling is extremely inferior to chip evacuation because the chip restraint on the flute groove and inner wall of the hole is severe. In this study, the effect of additive differences of brass on chip generation and evacuation performance is investigated. As a result, it clarified that different additives effect tool life. When silicon content was changed, tool breakage occurs immediately due to deterioration of chip discharge performance and an increase of hard phase. In addition, a change of zinc content cause early tool breakage in small diameter drilling of lead free brass due to a decrease in chip pitch interval.
The machine tool spindles supported by aerostatic bearings are a core component that determines machining accuracy of the ultra-precision machine tools. Typical desired level of the machining accuracy reaches submicron in the ultra-precision machining. However, there is some difficulties to satisfy the requirement, because of the thermal deformation by the heat generation during high-speed rotation of the spindle and low bearing stiffness due to the compressibility of air. In order to compensate the problems concerning the aerostatic bearings, the displacement control system of the aerostatic thrust bearings is designed in this study. The displacement control is made by controlling air flow into the bearings using a proportional flow control valve. A conventional feedback control system is designed based on a derived mathematical model. Performances of the designed feedback control system are experimentally examined in terms of the static and dynamic characteristics of the system. It was verified that the designed control system is able to control the displacement of the spindle with the positioning accuracy of 6 nm in the range of 0.0 to 10.0 μm. Step response of the system indicated that the settling time of the control system was over 10 seconds that will be reduced by further improvement of the controller.
The aim of this study is to investigate effect of plunging depth of welding tool on cross tension strength of Al alloy/CFRP friction lap spot joint. In this study, thermoplastic sheet was set between Al alloy and CFRP in order to join carbon fiber reinforced thermoset to Al alloy. In welding process, frictional heat is generated by contact between rotating welding tool and Al alloy. Generated heat is transferred from Al alloy to thermoplastic sheet. The thermoplastic sheet is melted and bonded to both Al alloy and CFRP. From results of cross tension test and observation of welding part, in case of shallow plunging depth of welding tool, generated heat was not sufficient to form welding part. On the other hand, in case of more deeper plunging depth of welding than thickness of thermoplastic sheet, Al alloy was directly contacted to CFRP, as a result, decrease in welding area. From result of measurement of axial load applied to the welding tool during the process, it is considered that higher axial load was generated to higher interfacial strength of CFRP/thermoplastic sheet and also tensile shear strength of Al alloy/ CFRP friction lap spot joint.
As a method to improve the efficiency of gas turbines, besides increasing the internal temperature and pressure of the turbine, clearance control is carried out by the use of abradable coatings. These coatings are applied by the thermal spray technique; however, this method has some disadvantages, such as a decreased adhesion when the coating is thick. So, the use of porous metals as an alternative to coating is suggested. In this study, first, samples of metallic foam materials were created from Al alloy A5052. Then, those materials were processed into test samples in order to investigate the friction and wear properties of the porous materials by means of a pin-on-disk wear test equipment. As a result, it was noted that the porous structure decreased the material's specific wear rate. That is, it was found that a porous structure influences the friction and wear properties of the material.
In previous research, it was reported that the elastic properties, particularly the flexural modulus, of the woven fabric composite laminate sharply decreases, especially when its number of laminated layers is reduced to a few layers, due to the intralaminar inhomogeneity which is caused by the architecture of interwoven yarns. In this study, buckling properties of the woven fabric composite laminate with a delamination under uniaxial compression load are investigated through finite element analyses. The influence of the reduction of elastic properties at the locally delaminated portion on the buckling load of the laminate is investigated. Two types of delamination are investigated, (i) delamination across the entire width of the laminate, and (ii) delamination locally introduced at the center of the laminate. Through the numerical investigations, it is found that the reduction of the elastic modulus at the delaminated portion can cause a significant reduction of the buckling load of laminate.
The aim of this study was to evaluate mechanical properties of particleboard formed from rice husk particles by hot pressing with a polyvinyl alcohol (PVA) binder. The rice husk was ground to powder and sieved to a diameter range of 500-125 μm. A preform was prepared using mixed rice husk particles, PVA powder, and purified water. The rice husk particleboard was fabricated by the hot pressing with the preform. Some mechanical properties (flexural strength and flexural modulus) of resulting particleboard were evaluated by three-points bending test. The particle morphology and particle size was investigated by scanning electron microscopy and digital microscope. Results showed that mainly, the rice husk particleboards satisfied the reference flexural strength (the flexural strength is 13 MPa or more) and the reference flexural modulus (the flexural modulus is 2.5 GPa or more) of 13 type of base particleboard according to JIS A 5908
Recently, the difference of flap opening/closing resistance of container boxes becomes one of severe problems for workers in various packaging industries. This kind of opening/closing resistance is desired to be even or at least similar in the both moving directions. In this recent situation, a new processing method is desired for performing the evenness of closing/opening resistance of the scored lines of container boxes. Currently used corrugated fiberboard is easy to bend in a single direction by score line processing. Therefore, we expect improvement of bending characteristics by changing the condition of score line processing. In this paper describes the bending moment resistance of scored portion of corrugated fiberboard (Cfb) and the corresponded bulging behavior of scored portion. In order to reveal the folding mechanism of scored Cfb using one-point type and three-point type die-set when varying the indentation depth of attacker bite, two kinds of prototype die-set were developed and the folding process was investigated using the folding test apparatus. The difference of one-point type and three-point type scoring was revealed as the characteristics of bending moment resistance of scored Cfb and the occurrence limit of failure modes of folding with respect to the folding direction.
Magnetic recording system require to increase capacity of memory, record at high speed and reduce power consumption. In recent years, a microscopic magnet is used on magnetic disc and accurate position control of magnetic head is performed in magnetic recording system, which make it possible to increase capacity of memory and record at high speed. Power consumption is changed by electric current. In fact, control of electric current is related to control of magnetic flux, which affect capability of recording. However, researches on magnetic flux focused on control of electric current have not been carried out sufficiently. In the analysis of magnetic field based on the finite element method, it is necessary to consider continuity of the magnetic flux density of normal direction on the interface among element. The node element does not satisfy this condition, however the edge element contain it. In this paper, the edge element is introduced based on mathematical theory, and basic example is carried out.
In this study, we present the estimation of shallow water flow field based on the ensemble Kalman filter FEM using the SUPG method. As the governing equation, the shallow water equation is introduced, and the Stream Upwind Petrov Gelerkin method (SUPG method), one of discretization method in the FEM, is applied to discretize the governing equation. The open channel model is emploed as the computational model.
In this research, 2D shallow water equations are expanded by an intrusive polynomial chaos approach for efficient uncertainty quantification in tsunami inundation flows. In this study an uncertain input is given on its bathymetry as well as its initial water height in the Thacker's inundation flow problem. Obtained uncertainty quantification results are compared with (exact) Monte-Carlo simulation results to validate the developed approach.
Kesel found a modified corrugated airfoil whose aerodynamic performance was similar to flat plates under low Reynolds number range. Numerical fluid analysis of a corrugated wings, which is a cross-sectional shape of dragonfly wing, is conducted. In this paper, the aim is to compare computed aerodynamic performance with the experimental value, and also to investigate the flow mechanism of the corrugated wings by visualizing vortices structures in detail.
In the present paper, misfit dislocation networks are introduced to coherent interfaces in order to express the stress and displacement distributions in incoherent interfaces. The interface zone, in which only traction transfers from one atomic layer in a layer to the opposite atomic layer, is introduced, then these regions slip against each other due to the misfit dislocation. The tractions in the interface zone depend on the displacements and the interface properties. Expressions for stress and displacement considering the interface properties are deduced using a three-dimensional Stroh's formalism. Bulk stress around the misfit dislocation increase due to the interface stress and the interface elastic moduli.