Kinds Of Plates Research Articles

Ultrasonic Vibration-Assisted Stamping of Serpentine Micro-Channel for Titanium Bipolar Plates Used in Proton-Exchange Membrane Fuel Cell.

Metallic bipolar plates (BPPs) are key components in the proton-exchange membrane fuel cell (PEMFC), which can replace traditional fossil fuels as a kind of clean energy. However, these kinds of plates, characterized by micro-channels with a high ratio between depth and width, are difficult to fabricate with an ultra-thin metallic sheet. Then, ultrasonic-vibration-assisted stamping is performed considering the acoustic softening effect. Additionally, the influence of various vibration parameters on the forming quality is analyzed. The experimental results show that ultrasonic vibration can obviously increase the channel depth. Among the vibration parameters, the vibration power has the maximum influence on the depth, the vibration interval time is the second, and the vibration duration time is the last. In addition, the rolling direction will affect the channel depth. When the micro-channels are parallel to the rolling direction, the depth of a micro-channel is the largest. This means that the developed ultrasonic-vibration-assisted stamping process is helpful for improving the forming limitation of micro-channels used for the bipolar plates in PEMFC.

Comparison of the Efficiency of Cross-Flow Plate Heat Exchangers Made of Varied Materials

This paper discusses a mathematical model for airflow through a cross-flow plate heat exchanger. The exhaust air is used to heat the supply air. Three kinds of plates are considered: made of aluminium, copper, and steel. The purpose of this research was to verify which material used to build the plate heat exchangers uses the exhaust air heat more efficiently. The method of the Trefftz function was used to determine approximate solutions to the analysed problem. The results obtained for 1.2 mm-thick plates and for external winter, summer, and spring–autumn temperatures are discussed. The results indicate that if the efficiency and price of the metals are considered, then steel is the best material for the plate heat exchanger. Thanks to the use of thin steel plates and the reduction in air exchange time to a few minutes, a cheap and efficient cross-flow heat exchanger can be obtained.

Mechanical properties of three-dimensionally printed titanium plates used in jaw reconstruction: preliminary study

The aim of this study was to compare the mechanical properties of three-dimensionally (3D)-printed and conventional surgical plates used for the repair of maxillary or mandibular defects under the same experimental conditions, and to provide experimental evidence for the future application and clinical trial of 3D-printed individualized surgical plates. For the experimental group, two groups of surgical plates with thicknesses of 2.0 mm and 2.5 mm were designed and 3D-printed by electron beam melting, using Ti–6Al–4V as raw material. Conventional commercially available surgical plates with the same thickness were adopted as the control group. A Vickers hardness tester and universal testing machine were used to measure the mechanical properties of the plates (hardness, bending strength, tensile strength, and yield strength). The mechanical properties of 3D-printed surgical plates were significantly better than those of conventional surgical plates of the same thickness (P < 0.001). Comparing the surgical plates of different thickness, the 2.5 mm-thick plates had the highest bending strength in the experimental group (P < 0.001) and the best hardness (P < 0.001), bending strength (P = 0.001), tensile strength (P = 0.001), and yield strength (P = 0.001) in the control group. No statistical difference was found between the two kinds of plates in the experimental group in terms of hardness (P = 0.060), tensile strength (P = 0.096), and yield strength (P = 0.496). The 3D-printed surgical plates have better mechanical properties than the conventional ones.

A non-incremental approach for elastoplastic plates basing on the Brezis-Ekeland-Nayroles principle

This paper is devoted to the numerical simulations of elastoplastic plates at small strains by using the non-incremental Brezis-Ekeland-Nayroles (BEN) principle. This space-time variational principle is based on the energy dissipation and transforms the boundary value problem into a null minimization one under constraints. Unlike the standard incremental procedure, the BEN principle characterizes the entire trajectory and delivers the mechanical fields at all time steps simultaneously. Two kinds of plates: the thin plate Love-Kirchhoff and the thick Reissner-Mindlin circular plates undergoing uniform pressure are studied respectively. The description of the dicretization of the principle using the mixed finite element method and the implementation are detailed. The obtained results are compared against analytical solutions provided in the literature and numerical predictions derived by the classical incremental procedure.

Relation between the geometric parameters and the composite heat transfer of paper honeycomb plates under cold-above/hot-below conditions and the corresponding influence mechanism

To develop functional honeycomb plates (HPs) with great thermal performance, This paper uses a heat flow meter to determine the equivalent thermal conductivity λ E of honeycomb plates (HPs) positioned horizontally under cold-above/hot-below conditions and combined with theoretical calculations, the influence mechanism of their geometric parameters on their heat transfer performance were investigated with different thicknesses h and cell wall lengths of 8 mm and 16 mm (HP8 and HP16, respectively). The results show that the thermal insulation performance of HPs with different cell side lengths varies with the plate thickness. HP8 presented a better thermal insulation performance when h = 40–60 mm. Based on this, the concepts of matching honeycomb structure and matching convection and the suggestions that according to the needs of a project, HP8 or HP16 can be reasonably selected, and the stacking of two kinds of plates can be optimized were first proposed. And it can be obtained that if the experimental λ E results of a HP are applied to a beetle elytron plate with the same thickness and honeycomb structure size, the heat insulation of the beetle elytron plate (BEP) would be superior to that of the HP. This paper lays a theoretical foundation for the research and development of multifunctional BEPs with heat insulation properties was verified. Finally, the internal influence mechanism of the difference in temperature distribution on the upper and lower surfaces and the three-dimensional size of the honeycomb cells on the matching honeycomb structure and matching convection. • HP 8 is a matching honeycomb structure when h = 10–20 mm, so its convection is stronger than HP 16 . • The increase in the convection of HP 16 was significantly faster than that of HP 8 and the radiation of two plates. • The conclusions can be applied to the multifunctional biomimetic beetle plate. • Four inferences point out the direction for further research in this field.

Numerical study on coupling flight characteristics of a plate-type windborne debris

In this paper, the flight characteristics of plate-type windborne debris are examined by the CFD numerical simulation method taking account of two-way fluid-structure interaction (FSI) between the plate debris and the wind field. Two kinds of plates with different sizes and masses are selected as the research objects, and the SST k-ω turbulent model based on the RANS method is used to solve the flow field around the plates. The unsteady three-degree-of-freedom responses of the plates are obtained by solving the motion equations. The real-time position updating of the flying plates in the wind field is realized by dynamic mesh technique. The effects of different grid numbers and time steps on the parameters of flight time, flight velocities and horizontal displacement are analyzed in detail. At the same time, the flight trajectories, time histories of the flight displacement and velocity, and change laws of the flight attitude of the plate are obtained. The results of the comparative analysis show that the numerical results of the present unsteady method are close to the measurement of wind tunnel tests. Compared with the quasi-steady method and the analytical method, the coupling effect will significantly increase the horizontal velocity and the resultant velocity of the plate, which will cause the plate debris to fly a farther distance in the horizontal direction.

The Influence of Boundary Layer Caused by Riblets on the Aircraft Surface

Drag reduction of riblets is one of the most important problems in drag reduction of non-smooth surfaces. In the past two decades, the use of riblets arranged along the flow direction to reduce frictional resistance has received considerable attention. In this paper, we study the plates with the triangular concave grooves, triangular protrusion riblets, trapezoidal concave grooves, trapezoidal protrusion riblets, and circular concave grooves. The numerical simulation method is used to calculate five kinds of plates with grooves and riblets under multiple working conditions. The results showed that the plates with grooves and riblets generated vortices inside the grooves, which separated the incoming flow from the wall surface, and by increasing the thickness of the boundary layer, greatly reducing the average velocity gradient of the wall surface, compared with the smooth flat plate, the friction resistance is reduced. But, lateral riblets and grooves cause additional pressure resistance, which is one order of magnitude higher than the friction resistance. Then, the triangular concave grooves are arranged on the suction and pressure sides of the NACA0012 airfoil, respectively. We calculated the aerodynamic parameters of the both airfoils, and the standard NACA0012 airfoil from the −8° attack angle to their respective stall attack angles. The results showed that the NACA0012 airfoil with triangular concave grooves on the suction side reduced the aerodynamic characteristics of the standard NACA0012 at a small angle of attack, but the stall angle of attack of the standard NACA0012 airfoil was improved, because the grooves ensure that some gas can flow normally on the suction side and delay the separation of the boundary layer. The NACA0012 airfoil with triangular concave grooves on the pressure side did not effectively improve the aerodynamic characteristics: lift–drag ratio decreased and stall angle of attack decreased, but it can increase the lift slightly.

Construction plate enforced by metamaterial elements

This research proposes new metal structural elements based on metamaterials as a replacement of conventional enforcement bars, which reduce metal consumption and increase stiffness and strength. Modern manufacturing machines based on lasers has a capability of fast one-side welding. This type of machines are standard now, what makes this procedure fast and cheap. Another aspect of the nowadays usage of metamaterials for construction works is the possibility to model them with all small details. Ten or twenty years ago modelling of numerous small elements covered by concreate was too expensive, even for one slab not to mention the whole building or a bridge. This work demonstrates one variant of metal reinforcement of concreate plate based on pyramid type elements. This type of pyramid reinforcements was inspired by the analysis of topology optimization of maximum stiffness of structure in case of bending. It was shown numerically, that under condition of three point bending such kind of plate has up to two times higher strength capabilities then conventional plate with equivalent metal consumption.

CLINICAL ASSESSMENT OF SUPRACONDYLAR FEMUR FRACTURE WITH RETROGRADE NAILING IN PATIENTS FROM BIHAR REGION

A distal femoral fracture is one of the challenging injuries to orthopaedic surgeons. Operative treatment has been the mainstay to obtain early mobilization of patients. Traditionally, stabilization has been achieved with open reduction using several kinds of plates. However, this conventional technique is not a biologic method; it requires large exposure, with its related risk of soft tissue damage, promoting devascularization of bone fragments and compromising fracture healing. [15] Based on above findings the present study was planned to study patient with distal femur fracture including both supracondylar fracture operated with retrograde femoral nail to evaluate the pre and post-surgical outcomes.&#x0D; The present study was planned in Department of Orthopaedic, Sri Krishna Medical College and Hospital (SKMCH), Muzaffarpur, Bihar, from jan 2018 to December 2018. Total 650 bone injuries were reported in the hospital. From that 15 cases of the supracondylar Fracture Femur were evaluated in the present study.&#x0D; The data generated from the present study concludes that retrograde intramedullary supracondylar nail is a good fixation system for the distal third femoral fractures, particularly the extra-articular type. The operative time is lessened with decrease in blood loss. Distal screw related local symptoms is a common problem, and is related to the implant and technique. Early surgery, closed reduction, at least two screws in each fragment, and early post-operative knee mobilisation are essential for good union, and good knee range of motion.&#x0D; Keywords: supracondylar, distal femur, retrograde nailing, biological fixation, femur fracture, etc.

A refined assumed strain finite element model for statics and dynamics of laminated plates

This work discusses some alternate models of a mixed assumed strain finite element which has been developed for laminated plates. After a brief theoretical review about this kind of plates and their possible finite element formulation, specifically devised for predicting the mechanical behavior of such structures, we discuss four possible assumptions for strains generating four kinds of mixed assumed strain finite elements. Several numerical tests performed on the aforementioned finite elements are thoroughly discussed in order to sketch some guidelines which can be useful when dealing with laminated plate problems.

Simulation and experiment of viscous torque for disengaged wet clutches of tracked vehicle

In order to predict the viscous drag loss for tracked vehicles, the drag torque of the friction pair with different grooves was investigated in this paper. The traditional computation method is difficult to adapt for the new kinds of friction plates with complex grooves. A numerical method with the help of CFD models is adopted to simulate the fluid flow status in the grooves and the drag torque was obtained by the accumulation of the discrete viscous force. The simulation results implied that the plates with different kinds grooves were provided with various characteristics of viscous torque and these characteristics could be affected by the rotation direction for the plate with spiral grooves, which are proved in experiment. Meanwhile, it was also found that the two kinds of plates with double arc or spiral grooves, which have different sensitive parameters in drag dissipation, have to perform accurate flow control and clearance design respectively. The simulations and experiments showed that the ‘positive spiral grooves’ friction plates had minimum drag torque in regular heavy-duty conditions. It can be used in transmission system with requirements of limited space and high mobility, which can lead to better heat dissipation and less power loss.

Elastic analysis of rectilinear orthotropic composite circular plates subject to transversal and in-plane load conditions using Ritz method

An analytical procedure for the analysis of elastic behavior of rectilinear orthotropic composite circular plate subjected to orthogonal and in-plane loads is presented. This kind of plates is composed of fiber-reinforced layers featuring fibers, differently oriented, arranged along rectilinear trajectories; composite lay-ups commonly employed for spot junctions are considered. The constitutive equations for rectilinear orthotropic composite circular plates are derived in the frame of classical lamination theory. The displacement components are determined, according to a novel approach, applying Ritz method to the virtual displacements principle for the load conditions treated in this work. The proposed framework is an approaching step for the theoretical definition of a Spot Joint Element able to simulate spot junctions (bolts, rivets or generic pins) applied to composite plates. To this purpose, displacement constraints deriving from the theoretical reference model of Spot Joint Element are considered. The employment of these specific boundary conditions required the derivation of suitable approximation functions, here reported in parametric form. Analytical results obtained by using the proposed procedure precisely match numerical results obtained by using refined FE models, for different aspect ratios of the plate and different laminate symmetrical lay-ups.

Electro-Optical Assays for Immunoindication of Microbial Cells

Background: Last years the development of various rapid methods for detection and identification of microorganisms is one of the most intensively growing research trends because they are available and in use in the industrial microbiological market today not only for microbiological diagnostics but for controlling food quality, pharmaceutical industry products and environmental control also. These methods tend to be nongrowth-based on various technology platforms. The more common technologies among them include nucleic-acid-based detection, which uses DNA or RNA targets; methods; enzymatic detection such as adenosine triphosphate (ATP) methods; flow-cytometry-based biochemical and various types of biosensors methods. The possibility of using the electro-optical method of analysis for the detection of microbial cells is very relevant and will be described in this paper. Methods: We undertook a structured search of bibliographic databases for peer-reviewed research literature using a focused review question and inclusion/exclusion criteria. The quality of retrieved papers was appraised using standard tools. The characteristics of our results were descriebed and were applied to analyse the findings of included studies using a conceptual framework. Results: In the article are described the results of the long-year research of our group devoted to developing of the real-time immunoindication (rapid detection) method basing on the registering of interactions of bacterial cells with polyclonal or phage display antibodies (the antibody-based detection) by the electro-optical analysis with the specially designed electro-optical sensor and to studying electro-optical characteristics of corresponding biological and physical processes occurring in the bacterial suspensions in the presence of various biological reagents. It was shown that the electro-optical analysis provides comparatively high sensitivity for cell detection and can be used for characterization of bacteria interactions with specific monoclonal antibodies, polyclonal antibodies or mini-antibodies. Also the theoretical fundamentals (basic principles) of the electro-optical analysis of microbial cells were described. Conclusion: The suggested electro-optical method can be recommended for analyzing of mixed cell suspensions (detection of bacterial cells in liquid phase) by using specific antibodies with further registration of their interactions measuring changes of electro-optical parameters, but without immobilization of antibodies on the solid surface (various kinds of plates). Keywords: Immunoindication, electro-optical analysis, electro-optical signal, electric-field orientation, Azospirillum brasilense, polyclonal antibodies, phage display technology, H-antigen, O-antigen, flagellin.

Structural analysis of transversally loaded quasi-isotropic rectilinear orthotropic composite circular plates with Galerkin method

Bending analysis of rectilinear orthotropic composite plates have been scarcely investigated taking into account the increasing use of composite materials in structural applications in the last years.This kind of plates are laminates with axisymmetric geometry and they are made up of unidirectionally reinforced layers with different orientations. Transversally loading this kind of circular plates, the deflected mid-surface is not independent from the circumferential coordinate, unlike the case of isotropic circular plate. Nevertheless, the quasi-isotropic stacking sequence makes still possible to introduce the hypothesis of axisymmetry for the mid-surface deflection under transversal load, disregarding the circumferential variation of the vertical displacement connected to the variable bending stiffness.Then, the constitutive equations for this specific family of plates were obtained finding the stress resultants-strains relations in the global cylindrical coordinate system. These expressions, along with the equilibrium equations, made it possible to derive the governing equation of the problem in the frame of Kirchhoff-Love hypothesis of the classical lamination theory.The Galerkin method was applied to solve the governing third order differential equation in terms of mid-surface deflection, introducing appropriate polynomial approximation functions compliant with the boundary conditions. In particular, fully clamped constraint conditions were considered for the outer diameter of the plate in conjunction with an internal rigid core. The characterization of this model allows to define the stiffness matrix terms of a custom composite bolted joint finite element, that is the object of future developments of this work.Results of the original proposed method are presented and compared to those obtained by means of FEA performed with a refined reference model, demonstrating a good agreement.

CFD-Based Selection of Dispersion Plates

Computational Fluid Dynamics (CFD) technology was used to analyse dispersion effects of 3 plates of different structures during adhesives production. Three models of the dispersion plates were designed: (1) Project 1: a plate with sharp and short teeth, (2) Project 2: a plate with sharp and long teeth, (3) Project 3: a plate with blunt and long teeth. Pictures of velocity flow contours and flow trajectories in the CFD analysis were obtained to show the flow conditions inside the Reactor. Particle studies were also run to predict adhesive particles dispersion effects of these 3 kinds of plates, so that the best structure of the plate would be chosen.

Experimental proof of applicability of alternative sort of plating of contemporary copper forgeries with use of mercury

Abstract Practical applicability of alternative sort of coating of contemporary copper forgeries with use of mercury only (i.e. without use of another metal such as silver or tin) has been experimentally definitely proven. This undescribed way of amalgamation coating is based on simple dipping of a cleaned copper flan in mercury. In few hours, a stable silvery layer of the copper amalgam covers the copper surface. This kind of plating was most likely used by forgers in process of plating of the copper forgeries copying parvi of Wenceslas II at the beginning of the 14th century.

Study on the structural optimization of hatch cover consist of several kinds of plates

The purpose of this research is to reduce the volume of hatch cover consists of several kinds of plates by developing structural optimization method. The objective function is minimization of the volume. The design variables is a thickness of plate or sectional area. Constraint is 4 kinds of stress, Mises stress, bending stress, shearing stress, buckling stress. I used stress ratio to get optimal solution. The stress ratio is the solution that actual stress divided by allowable stress. Structural optimization of hatch cover consists of several kinds of plate is carried on by decreasing allowable stress of plates have high allowable stress in several kinds of plates is connected. This study succeeded in reducing volume by overcoming the problem of optimization observed when arranging several kinds of plates having in each division influences each other. Furthermore, this study succeeded in reducing volume by changing optimization technique of stiffeners by using stress ratio of plate.

Two-scale topology design optimization of stiffened or porous plate subject to out-of-plane buckling constraint

This paper studies maximum out-of-plane buckling load design of thin bending plates for a given amount of material. Two kinds of plates are considered. One is made of periodic homogeneous porous material. Another is uniformly stiffened solid plate. The plate material, thickness, design domain of its middle plane and boundary conditions are given. The pattern of prescribed in-plane external load or displacements along the part of boundaries, which move freely, is given. Both plate topology and micro-structural topology of porous material or stiffener layout are concurrently optimized. The artificial element material densities in both macro and micro-scale are chosen as design variables. The volume preserving nonlinear density filter is applied to obtain the black-white optimum topology and comparison of its different sensitivities is made to show the reason for oscillation during optimization process in Appendix. The new numerical implementation of asymptotic homogenization method (NIAH, Cheng (Acta Mech Sinica 29(4): 550---556, 2013) and Cai (Int J Solids Struct 51(1), 284---292, 2014) is applied to homogenization of periodic plate structures and analytic sensitivity analysis of effective stiffness with respect to the topological design variables in both macro-scale and micro-scale. On basis of that, this paper implements the sensitivity analysis of out-of-plane buckling load by using commercial FEA software and enables the application of gradient-based search algorithm in optimization. Several numerical implementation details are discussed. Three numerical examples are given to show the validity of this method.

Investigation on Shearing and Local Formability of Hot-Rolled High-Strength Plates

In order to evaluate the shearing quality, the material inhomogeneity through thickness after shearing is introduced by the authors. This study investigates the shearing and local formability of hot-rolled high-strength steel (HSS) plate, which is generally exploited for the manufacturing of the beam of heavy trucks. Various kinds of plates with different thicknesses and strengths are used to figure out the effect of material properties on the shearing quality. Both the shear surface morphology and microhardness distribution of the sheared edge are considered for evaluating the influence of the sheared-edge quality on local formability during the following forming process. Vickers hardness tests are conducted to analyze the microhardness distribution on the shear surface, which is proved to have significant effect on the local formability of the sheared edge. Furthermore, two kinds of bending tests and simulation are employed to study the edge cracking phenomenon, and the results indicate that the junctional zone of burnished zone and fracture zone, which is defined as peak hardness zone (PHZ), has a significant impact on major strain distribution on shear surface in the side bending test and this region is the main cause of edge cracking in normal bending test.

Microstructure characteristics and phase transformations of the Ni-P and Ni-P-Re electroless deposited coatings after heat treatment

The microstructure and phase composition of Ni-P and Ni-P-Re layers with medium phosphorus content of 8.8 and 8.2wt. % of P, respectively, and 6.8wt.% of Re electroless plated on copper substrate were studied. Both of the deposits showed amorphous X-ray profile, however, as it was expected, the presence of small (about 10nm in size) nanocrystallites was observed in both kinds of plating under transmission electron microscope (TEM). The crystallization temperatures, measured in the range of 298–773K, significantly increased with rhenium content as well as with increasing heating rate and differed by about 40K. The activation energy calculated based on the Kissinger’s model in the case of Ni-8.2P-6.8Re plating was 217.7kJmol−1 and for Ni-8.8P was 206.3kJmol−1. X-ray diffraction (XRD) measurements of the Ni-P deposits carried out after the heat treatment indicated the presence of the Ni and Ni3P phases, which was confirmed by electron diffraction and high resolution observations in TEM. XRD data concerning Ni-P-Re plating revealed the following phases: Ni, Ni3P, Ni0.21Re0.79, Ni5P2 and NiP, while TEM investigation confirmed the presence of Ni3P, NiP, Ni5P2 so far. Due to the very local information gathered from the TEM, this result needs further studies.