Ribbed Plate Research Articles

Scattering from a finite ribbed plate with attached oscillators.

Double layer structures consisting of stainless steel and polymer rods are designed to blur and attenuate Bragg and Bloch-Floquet scattering from a periodically ribbed plate in a given frequency bandwidth. These structures can be considered as ribbed plate-spring-mass systems, the resonance frequencies of which are obtained from random and circular permutations of five basic oscillators. Analytical and finite element methods are used to find their parameters and tank tests have been carried out to ensure the accuracy of the numerical results and validate the relevance of such a model. It has been found that the typical features associated with the periodicity of the ribs are replaced by a "Christmas tree" appearance when the far field pressure backscattered from the model is displayed in the (frequency, aspect angle) plane. An analysis of backscattering patterns is presented and comparisons with Naval Research Laboratory results are made.

Numerical Study on Heat Transfer Enhancement in a Rectangular Duct with V-Shaped Ribs

This research aims to study the numerical investigation of heat transfer and fluid flow characteristics of multiple cylinder v-rib with combined staggered rib in a rectangular duct. The conventional heat exchangers were usually used as flat plate rib shape leading to increase pressure drop from obstructive flow. Therefore, the inclined cylinder V-shaped rib was modified to use in this work. The cylinder shape rib increases pressure drop (less than flat plate rib) because of the rounded shape of cylinder v-rib creating the smooth flow of the fluid. The heat transfer and the pressure drop are represented in term of Nusselt number (Nu) Friction factor (f), respectively. The relation of Nu with f values was analysed to obtain the Thermal performance enhancement factor (TEF). The velocity vector and temperature contours were examined by the Computational Fluid Dynamics (CFD). The data was compared with the experimental result. The channel size was simulated at the rectangular duct height (H) of 30 mm and width (W) of 300 mm with rib-to channel-height ratios (e/H) at 0.1, 0.2, 0.3 and the angle of attack (α) at 30°. Air was used as the test fluid. Reynolds number (Re) was varied from 12,681 to 35,000 with constant heat flux on the bottom wall of the tested section. Simulation results represented the velocity vectors and temperature contours. It was found that the increasing of e/H leading to provide high co-rotating of the flow. The highest TEF (TEF = 2.05) was observed at 30(, e/H 0.3 and Re 12,618.

Operative Stabilization of Chest Wall Trauma: Single-Center Report of Initial Management and Long-Term Outcome.

Conservative treatment of even severe thoracic trauma including flail chest was traditionally the standard of care. Recently, we reported possible benefits of surgical chest wall stabilization in accordance with other groups. The aim of this study was to critically review our indications and results of internal fixation of rib fractures in the long-term course. We retrospectively analyzed the data of a consecutive series of patients with internal rib fracture fixation at our institution from 8/2009 until 12/2014, and we retrospectively studied the late outcome through clinical examination or personal interview. From 1398 patients, 235 sustained a severe thoracic trauma (AIS ≥3). In 23 of these patients, 88 internal rib fixations were performed using the MatrixRIB® system. The median age of these operated patients was 56 years [interquartile range (IQR) 49-63] with a median ISS of 21 [IQR 16-29]. From 18 local resident patients, follow-up was obtained after an average time period of 27.6 (12-68) months. Most of these patients were free of pain and had no limitations in their daily routine. Out of all implants, 5 splint tips perforated the ribs in the postoperative course, but all patients remained clinically asymptomatic. Plate osteosynthesis showed no loss of reduction in the postoperative course. No cases of hardware prominence, wound infection or non-union occurred. In our carefully selected thoracic trauma patients, locked plate rib fixation seemed to be safe and beneficial not only in the early posttraumatic course, but also after months and years, patients remain asymptomatic and complete recovery as a rule. Trial registration number KEK BASEC Nr. 2016-01679.

Dynamics of periodic ribbed plates with inner resonance: Analytical homogenized model and dispersion features

The dynamic behavior of a periodic ribbed plate with local resonance is investigated. The behavior of the cell made of a beam clamped along a plate edge analyzed through multi-scale asymptotic method enables to derive the governing equations of the effective mechanical behavior. This approach allows obtaining a full homogenized analytical model that provides a relevant representation of the flexural and torsional mechanisms at both global and local scales. The complex dynamic behavior is shown to encompass several mechanisms associated with enriched kinematics. Two types of flexural and torsional waves are evidenced and governed by two distinct differential equations that describes (i) waves where both beam and plate moves, and (ii) guided waves where the plate only is set in motion. The inner resonance of the plate induces unconventional dispersion features, with singularities associated either with the symmetric eigenmodes for the bending waves or the antisymmetric modes for the torsional waves. The guided waves are alternatively related to the symmetric and antisymmetric modes of the bended plate and are propagative above the corresponding eigenfrequencies. The predictions of the homogenized model are successfully compared to numerical calculations conducted using Wave Finite Element based methods, for two realistic examples of ribbed plates. The study provides design rules to tailor ribbed plate panels having specific atypical features in a given frequency range.

Chest Wall Stabilization Leads to Shortened Chest Tube Stay Time in Rib Fracture Patients after Traumatic Chest Wall Injury

Rib fixation has become a strategy for patients with displaced rib fractures and hemo/pneumothoraces (HTX/PTX). Rib plating improves pain control and respiratory mechanics, thereby reducing recovery times and morbidity/mortality. Current treatment consists of chest tube placement, pain control, and pulmonary toilet. The addition of rib plating should reduce time till HTX/PTX resolution and chest tube removal. The study compares chest tube stay time in rib-plated patients with those managed with current treatment. We hypothesize that patients undergoing rib plating will have a reduction in chest tube stay times. A retrospective review of a Level 1 trauma registry was performed. Rib-plated patients (n = 70) from 2013 to 2015 were compared with a randomly selected, nonoperative, injury-matched, historical (2003-2008) control group (n = 60). Demographics were obtained. Independent variables analyzed include Injury Severity Score (ISS), intensive care unit days, length of stay, and chest tube stay times. 60 control patients had an average ISS of 19 and age of 51 years, compared with ISS of 20 and age of 56 years in plated patients. Plated patients had a reduction in chest tube days, 6.5 versus 8.4 days, P value = 0.02. Plated patients had 14 intensive care unit days versus 19 days, P value = 0.09. T tests were performed to confirm significance. Reduction in chest tube days improves patient pain and allows for improved ambulation and pulmonary toilet, helping reduce respiratory complications. Our review shows that plating may prove beneficial in reducing complications associated with management of HTX/PTX in the setting of rib fractures.

LAGRANGIAN METHOD FOR ALGORITHM OPTIMIZATION OF RIBBED THIN PLATES

The paper presents two iteration algorithms for the equation solution using the method of Lagrange multipliers. It is shown that these iteration algorithms do not converge. For comparison, we use the optimum parameters of a ribbed plate obtained by other methods. The proposed method is based on the specific properties of optimality of ribbed plates formulated as a result of the Lagrange equation analysis. These optimum parameters satisfy each of Lagrange equations. The solution of these equations shows that optimization of ribbed plates is possible only with the use of specific optimality properties.

Study on Assembly Mechanics and Its Effect on the Performance of Proton Exchange Membrane Fuel Cell

Proton exchange membrane fuel cell (PEMFC) is an energy conversion device, which converts the chemical energy of fuels into electrical energy directly through electrochemical reactions, it has been considered as one of the most promising clean energy conversion devices widely because of its wide range of fuel sources, clean and free pollution, high operating current, can start-up quickly at room temperature and other advantages. All of components of a PEM fuel cell need to be assembled by exerting pressure from the outside, since the gas diffusion layer (GDL) is a porous structure and its elastic modulus is relatively small, during the process of exerting pressure, if the assembly pressure is too large, it will cause the GDL over deformation or even irreversible damage, thus reducing the gas transmission channel, increasing the mass transfer resistance, and even will damage the fuel cell components, shorten the lifetime of the fuel cell; in contrast, if the assembly pressure is too small, due to the poor contact between the bipolar plate and GDL, the contact resistance will increase, which will lead the reduce of the fuel cell efficiency, and the leak tightness of gas will not be guaranteed, there will be a risk of fuel gas leakage. In this paper, the numerical simulation method is used to simulatethe deformation of GDL under different assembly pressures, and the influence of transmission parameters such as GDL porosity and permeability caused by assembly pressure and its influence on the performance of PEMFC are studied in order to get the optimum pressure, making the best performance of PEMFC. The main work and achievements are as follows: The single channel PEMFC geometric model is established, and the numerical simulation is used to simulate, and the parameters such as porosity and permeability of PEMFC under different assembly pressures are calculated according to the empirical formula. When the assembly pressure from 0 to 3.0 MPa, the porosity decreased from the initial value of 0.78 to about 0.38; permeability also has an order of magnitude change; and the contact resistance decreases as the assembly pressure increases, but it decreases gradually; The finite element analysis (FEA) is used to analyze the effect of different assembly pressures on GDL deformation. The results show that, under the action of assembly pressure, the part of GDL, which under the bipolar plate ribs, will be deformed in different degrees, and the deformation on both sides is similar and obvious, the degree of deformation increases as the assembly pressure increases, while the part of GDL, which under the channel, is almost unchanged; Through the simulation, the distribution of the components concentration in the single channel PEMFC flow channel and the polarization curves under the assembly pressure are analyzed, and compares with different assembly pressures. Since the gas in the flow channel reacts in the catalyst layer, the gas concentration decreases along the flow direction under different assembly pressures. For the polarization curves, when the assembly pressure is between 0.5 to 1.0 MPa, the same operating voltage, the fuel cell current density is greater than the case of other pressures, and the fuel cell with the highest power under this pressure. Therefore, when the assembly pressure between 0.5-1.0 MPa, the single channel PEMFC performance is optimal.

An Improved Model for the Analysis of Plates Stiffened by Parallel Beams Including Creep and Shrinkage Effects: Application to Concrete or to Composite Steel-Concrete Structures

In this paper, an improved model for the static analysis of reinforced concrete plates stiffened by arbitrarily placed parallel reinforced concrete or steel beams with deformable connection taking into account the influence of creep and shrinkage effects relative with the time of the casting and the time of the loading of the plate and the beams is presented. According to the proposed model, the stiffening beams are isolated from the plate by sections in the lower outer surface of the plate, making the hypothesis that the plate and the beams can slip in all directions of the connection without separation (i.e. uplift neglected) and taking into account the arising tractions in all directions at the fictitious interfaces. These tractions are integrated with respect to each half of the interface width resulting two interface lines, along which the loading of the beams as well as the additional loading of the plate is defined. Their unknown distribution is established by applying continuity conditions in all directions at the interfaces taking into account their relation with the interface slip through the shear connector stiffness. The utilization of two interface lines for each beam enables the nonuniform distribution of the interface transverse shear forces and the nonuniform torsional response of the beams to be taken into account describing better in this way the actual response of the plate - beams system. The analysis of both the plate and the beams is accomplished on their deformed shape taking into account second-order effects. Six boundary value problems are formulated and solved using the Analog Equation Method (AEM), a BEM based method. The solution of the aforementioned plate and beam problems, which are nonlinearly coupled, is achieved using iterative numerical methods. The adopted model describes better the actual response of the plate - beams system and permits the evaluation of the shear forces at the interfaces in both directions, the knowledge of which is very important in the design of prefabricated ribbed plates. The evaluated lateral deflections of the plate - beams system are found to exhibit considerable discrepancy from those of other models, which neglect inplane and axial forces and deformations. Numerical examples with great practical interest are presented.

Numerical investigation of hydrogen absorption in a stackable metal hydride reactor utilizing compartmentalization

In this paper, a three-dimensional model for hydrogen absorption in a metal alloy has been developed, validated against the experimental data in the literature, and then applied to a novel design for a hydrogen storage unit. The proposed design is similar to the fuel cell stack, but here the Membrane Electrode Assembly (MEA) has been replaced by a metal hydride (MH) reactor placed between the flow-field plates. These are stacked together to achieve the required amount of hydrogen storage. The flow-field plates have channels engraved on one side for hydrogen supply and on the other, for coolant/heating medium. It is known that the effectiveness of a hydrogen storage unit is directly related to its heat transfer area, and therefore, the choice of its geometry is very important. The larger the size, the more the resistance to heat transfer. Although, the internal tubular heat exchangers have proven to be effective in heat transfer, they pose severe challenges such as cooling/heating medium leakage due to tube erosion, stresses generated, etc. and they displace the active metal hydride from the tank. The present stacked MH reactor configuration helps to overcome these challenges by stacking small MH reactors together and there is no chance of the cooling/heating medium leaking into the metal hydride. Numerical simulations were performed to investigate the effect of coolant flow rate and percentage of flow-field plate rib area exposed to the MH reactor on temperature evolution and the amount of hydrogen stored. Further, a detailed study was carried out to understand the effect of compartmentalization of the MH reactor on temperature distribution. The results revealed that compartmentalization substantially helps to uniformly distribute the temperature in the metal bed, which is very important to maintain uniform utilization of the metal powder. Consequently, the uniform metal powder density for repeated absorption-desorption cycles without significant loss of its hydrogen storage capabilities.

Second law of thermodynamics analysis for nanofluid turbulent flow inside a solar heater with the ribbed absorber plate

Employing rough surfaces and nanofluids in solar heater ducts are recognized as effective techniques to improve thermal performances of these devices. In this paper, the second law of thermodynamics analysis is performed for nanofluid turbulent flow in a solar heater duct with rib roughness on the absorber plate. The effects of different parameters including rib height, rib wedge angle, rib pitch, Reynolds number, and nanofluid concentration on thermal and frictional irreversibilities are investigated. The results indicated that the thermal entropy generation decreases about 11.1% by using nanofluid with concentration of 0.04. The frictional and thermal entropy generations decrease by increasing the rib pitch. Moreover, the thermal entropy decreases about 21.05% by increasing the rib height in the range of 0.025–0.033 for Re = 3200. Finally, it is found that the thermal entropy generation decreases by increasing the wedge angle of the rib.

Design and strength analysis of a fertilizing and soil covering vehicle

In this paper, a kind of fertilizing and soil covering vehicle is designed with compact structure, easy control and substituting manual work to conduct the operations including fertilizing and soil covering. In accordance with movement, structure and loading feature of fertilizing and soil covering vehicle, parametric modeling is carried out for the frame part of this fertilizing and soil covering vehicle to define boundary conditions such as load, constraint, etc. when the frame is under the working condition of normal full load. ANSYS software is used to produce finite element model of frame, and to analyze and solve the model, so as to obtain stress and stain variation diagram of each part of frame under working condition of normal full load. The calculation result shows that: the structure of frame is able to meet the strength requirement, and the maximum value of stress is located at joint between frame and external hinge, which should be appropriately improved in thickening way. In addition, a larger deformation occurring at damper on lower part of hopper may be reduced by adding rib plate at damper on lower part of hopper. The research result of this paper provides the theoretical basis for the design of frame of fertilizing and soil covering vehicle, which has deep theoretical significance and application value.

Ozone Generator Aluminum Electrode Soldering

The creation of an entirely soldered ozone electrode component is proposed and implemented for the first time by the authors. Electrode construction with a ribbed plate insert within it is the most perfect heat exchange device from the point of view of effective heat exchange and uniform distribution of liquid flow through its section. Stages are considered for electrode preparation for soldering and a standard heating cycle is proposed for soldering and electrode with eutectic silumin. It is shown that as a result of the soldering thermal cycle metal structure becomes coarse-grained and favorable for subsequent electrochemical formation of a nanostructured anodic oxide coating 50–60 μm thick.

An analytical study of the free and forced vibration response of a ribbed plate with free boundary conditions

An analytical study to predict the vibration response of a ribbed plate with free boundary conditions is presented. The analytical solution was derived using a double cosine integral transform technique and then utilized to study the free and forced vibration of the ribbed plate, as well as the effect of the rib on the modal response of the uniform plate. It is shown that in addition to the three zero-frequency rigid body modes of the plate, the vibration modes of the uniform plate can be classified into four mode groups according to the symmetric properties of the plate with respect to the two orthogonal middle lines parallel to the plate edges. The four mode groups correspond to a double symmetric group, a double anti-symmetric group and two symmetric/anti-symmetric groups. Whilst the inclusion of the rib to the plate is shown to cause distortion to the distribution of vibration modes, most modes can still be traced back to the original modes of the uniform plate. Both the mass and stiffness of the rib are shown to affect the modal vibration of the uniform plate, whereby a dominant effect from the rib mass leads to a decrease in the modal frequency of the plate, whereas a dominant effect from the rib stiffness leads to an increase in plate modal frequency. When the stiffened rib behaves as an effective boundary to the plate vibration, an original plate mode becomes a pair of degenerate modes, whereby one mode has a higher frequency and the other mode has a lower frequency than that of the original mode.

Cyclic Behavior of Steel Beam-to-Column Moment Connections Using Different Sizes of Flange Plates and Reinforced by a Single Rib Plate

This paper presents a numerical study on the behavior of connection between steel I-beam and H-column when are affected by cyclic loading. The connection used the flange plates to connect the beam flanges to the column flange. They were welded to the top and bottom flange plates and created a welded flange plate (WFP) connection. Specimens were six models of WFP connections with different beam geometry and flange plate sizes which were modeled and their cyclic behavior were investigated using finite element analysis in ABAQUS program. Three of them were reinforced by a vertical triangular top and bottom rib plates, and others remained unreinforced. The results showed that reinforcement with a vertical triangular rib plate attached to the top and bottom flange plates can improve cyclic behavior of WFP connections. By using a rib plate, the equivalent plastic strain was increased and showed better plastic hinge formation compared to those with no vertical rib plate. Those models with IPB beam sections had the best cyclic behavior compared to those with IPE beam sections and satisfied the acceptance criteria of AISC seismic provisions for intermediate and special moment frames. We concluded that those WFP connections which did not satisfy the criteria of AISC seismic provisions for special moment frames, can be upgraded by a vertical triangular rib plate in order to be used in special moment frames.

Cyclic Behavior of Bolted Extended End-Plate Moment Connections with Different Sizes of End Plate and Bolt Stiffened by a Rib Plate

This paper presents a numerical study on the behavior of prequalified Bolted Extended End Plate (BEEP) moment connections when are affected by cyclic loading. Specimens were six four-bolt extended end-plate connections consist of H-shaped columns and I-shaped beams with different geometry as well as different end-plate size and bolt diameter; three of them were stiffened by a triangular rib plate welded to the top and bottom of the beam flanges, and others remained unstiffened. They were modeled in ABAQUS software and their cyclic behavior was evaluated using finite element analysis. Responses of specimens were examined by presenting their equivalent plastic strain, stress distribution, and moment-rotation hysteretic curves. Results revealed that with the increase of beam height and inertia moment in equal story drift rotations, the reduction of connection strength occurred earlier due to the occurrence of local buckling in the beam web and flange after subjecting to cyclic loading. By comparing moment-rotation hysteretic responses of specimens, it was found out that in unstiffened BEEP connections with thinner end-plate, the use of single vertical rib stiffener can slightly improve their cyclic behavior, but in connections with thicker end plate, it showed no considerable effect. It was concluded that the BEEP connections whose dimensions are not based on the tenth code of the Iranian national building regulations, cannot satisfy the criteria of AISC seismic provisions for both special and intermediate steel moment frames, although they experienced no local beam web and flange buckling.

Failure analysis of ribbed cross-laminated timber plates

The process of material failure i.e. cracks development and their propagation in an experiment related to the bending collapse of cross laminated timber plate with ribs is described. Numerical simulation of such an experiment by the nonlinear finite element method is presented. The numerical model is based on Hashin failure criteria, initially developed for unidirectional composites, and on material softening concept applied by the smeared crack approach. It is shown that such a numerical model can be used for an estimation of the limit load and the limit displacement of a cross laminated timber ribbed plate.

Modification of pre-Kobe column-tree moment resisting connection

Modified details were proposed for pre-Kobe column-tree moment resisting connection in the current study. The performance of the traditional pre-Kobe column-tree system is numerically evaluated and compared with four modified configurations which include single and double rib plate, cover plate and also reduced beam section. The results of nonlinear finite element analyses revealed the perfect amelioration of modified connections in several aspects of behavior such as increasing the load bearing capacity and moment resistance, improvement of cyclic and inelastic behavior and enhancement of energy dissipation. A rating checklist which compares the advantages of each connection in different aspects of behavior has been also presented which helps to compare the behavior of proposed models.

Traumatic thoracic rib cage hernias: Operative management and proposal for a new anatomic-based grading system

BackgroundTraumatic Rib Cage Hernias (TRCH) requiring operative repair are rare and there is currently no literature to guiding surgical management. MethodsPerioperative review of TRCH over 32 years. Five operative grades were developed based on extent of tissue/bone damage, size, and location. ResultsTwenty-four patients (20 blunt, 4 penetrating) underwent operative repair. Lung was the herniated organ in 88% with a median of 4 rib fractures and average size of 60.25 cm. Types of operation were well clustered by assigned TRCH grade. The majority required mesh (75%) and/or rib plating (79%). Complex tissue flap reconstruction was required in 10%. Full range-of-motion was maintained in 88% with79% returning to pre-injury activity levels. Five patients had continued pain at final follow up (mean = 7months). ConclusionThe size and degree of injury has important implications in the optimal surgical management of TRCHs. These operative grades effectively direct surgical care for these rare and complex injuries.

Vibration Modal Analysis and Optimization of the Motor Base

When the motor works normally, its base will vibrate. The structure will generate the resonance and result in damage of the mechanical equipment when the vibration frequency reaches the natural frequency. The article which is based on the modal analysis of the motor base compares the natural frequencies in different boundary constraints in order to select appropriate way to install the motor base, and optimizes the motor base by contrasting different effects on the natural frequencies of the different thickness of the ribbed plates for selecting reasonable structure to prevent resonance.

Experimental investigation of explosive weld of bimetal ribbed plate based on boss charging

The large-area Cu/SS ribbed plate is very significant for the fusion engineering but is difficult to produce by regular cold or hot processing. This thesis takes Cu-alloy plate and 316L SS ribbed plate as materials and adopts a new form of charging to carry out the deepened study and optimization of the supporting formwork from perspectives of design, filling scheme and welding parameters. It prepares a large-area dual-metal ribbed plate by the explosive weld and conducts the shear strength test, metallographic observation, scanning electron microscopy and micro-hardness test of the weld interface. The result indicates that most weld interface is the wavy metallurgical bond interface of the direct transition of Cu/SS but “coronary” vortexes containing metallic oxide exist on both sides of the crest. Crystalline grains near the bond interface are lengthened and thinned, the micro-hardness is increased significantly and the bond strength of interface is even greater than that of copper.