Ribbed Plate Research Articles

Optimization design of the internal structural support of marine turbine blade for weight reduction: A preliminary study

Weight reduction is important when additive manufacturing becomes feasible for marine turbine runner. Hydrofoils are usually used as the simplified model of turbine blade for investigating complex problems. A NACA0015 hydrofoil is used to explore the weight reduction by setting internal structural support instead of the solid foil. Firstly, computational fluid dynamics (CFD) simulation is conducted to have the hydraulic loading. Then, fluid-solid interaction (FSI) method is used to evaluate the stress and deformation of the initial solid foil. Rib plates are used as the internal structural support with two main parameters that the rib width trib and angle of rib γrib. The global dynamic-criterion (GDC) algorithm is used for optimizing the uniformed maximum stress SND and the uniformed weight WND of foil. Finally, the optimal foil is found with trib of 1.716 mm and γrib of 69.44°. The value of SND is 1.595 times of the initial foil and WND is reduced by 46.6%. A compromise solution is effectively found for both sufficient strength and lower weight. Grey relation analysis shows that the influence of trib is stronger than that of γrib especially for the weight. This study helps the additive manufacturing of marine turbine runner and blades.

Heat transfer enhancement by pulsating flow of a viscoelastic fluid in a microchannel with a rib plate

ABSTRACT In order to improve the heat transfer performance of the microchannel heat exchanger, a composite heat transfer enhancement method was proposed. Viscoelastic fluid was used as working fluid in pulsating flow condition, and rib plates were added to the microchannel to bring extra disturbance to the flow. The Oldroyd-B constitutive model of the viscoelastic fluid was used in the numerical simulation, and the flow field, temperature field, Nusselt number (Nu), and pressure drop were analyzed when the average Reynolds number (Re) is 10. Both Strouhal number (St) and amplitude are important factors affecting heat transfer, but they have an insignificant influence on pressure drop at low Reynolds number. The St = 0.125 and amplitude A = 0.8 are better parameters. The increase of Weissenberg number (Wi) will cause the vortex to split into several subsidiary vortexes during its development, which will also develop to various positions in the channel, thus further enhancing the heat transfer. When the Wi is in the range of 1 ~ 5, the performance evaluation criteria rises at a relatively fast rate, from 1 to 1.404.

Analysis on Welding Temperature Field and Stress Field of Boring Bar of New Boring Machine

Ansys software is used to simulate the welding process of the boring bar of the new cylinder head boring machine. The indirect coupling method is used to analyze the temperature field, then the stress field and deformation. It is found that for the double support structure, the highest temperature occurs at the outer stiffened plate of the small diameter end, and the lowest temperature occurs at both ends of the inner support structure. The deformation of the whole structure mainly comes from the axial deformation, and the maximum deformation occurs at the large diameter end of the outer rib plate. Because the role of the supporting web is to limit the large deformation of the whole structure, the structure at the small diameter end is firmer and has the ability of anti-deformation. In terms of technology, the influence caused by deformation can be compensated by the compensation design of machining amount.

Outcomes After Operative Reconstruction of Symptomatic Rib Nonunions.

To assess the outcomes of patients after rib nonunion reconstruction. Retrospective case series. Level 1 trauma center. Between January 2007 and August 2019, 25 consecutive patients with 51 nonunions with disabling pain or chronic instability were treated for nonunited rib fractures. Rib nonunion reconstructions performed using plate and screw fixation, recannalizing the medullary canal and augmented with autogenous iliac crest bone graft. Patient demographics, mechanism of injury, number of rib nonunions, and postoperative radiographs were assessed. Satisfaction, patient-reported complications, return to occupation and activity, and general health measures were captured using patient questionnaires. In 25 patients, 51 painful rib nonunions were surgically treated. The average length from injury to surgical rib reconstruction was 25.1 months (range = 3-118 months; median = 12 months). Follow-up was obtained in 18 of 25 patients (72%) with a mean of 46.1 months (range = 13-139 months). All ribs achieved radiographic union at an average of 12.3 weeks (range = 8-24 weeks) after surgery. Sixteen of 18 patients (89%) reported satisfaction with surgery and 15 patients (83%) reported mild to no pain at final follow-up. Five patients had complications that all resolved after subsequent treatment. Successful treatment of symptomatic rib nonunion is possible using rib plates in conjunction with bone grafting and has high union rates, satisfactory results, and limited complications. Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Optimization of the bipolar plate rib structure in proton exchange membrane fuel cells with an analytical method

In order to make proton exchange membrane fuel cell vehicles more marketable, not only should costs be reduced, but service life should also be further increased. Important factors determining the expected service life are the deformation and the stress distribution within the carbon paper gas diffusion layer (GDL), on which the rib structure of the bipolar plates (BPP) has a significant impact. Against this background, a new analytical method is firstly developed to predict the deformation and stress distribution within the GDL, due to compression by the ribs, with high accuracy and low computing resources. Based on the analytical method, a new parabolic rib geometry is then proposed, which can significantly reduce the maximum normal and shear stresses occurring within the GDL, thus reducing the possibility of its mechanical damage. The optimized rib design provides guidance for designing and processing commercial fuel cell BPPs.

Bond Behavior of Concrete-Filled Steel Tube Mega Columns with Different Connectors.

Concrete-filled steel tubes (CFSTs) are widely used in construction. To achieve composite action and take full advantage of the two materials, strain continuity at the steel–concrete interface is essential. When the concrete core and steel tube are not loaded simultaneously in regions such as beam or brace connections to the steel tubes of a CFST column, the steel–concrete bond plays a crucial role in load transfer. This study uses a validated finite-element model to investigate the bond-slip behavior between the steel tube and concrete in square CFST mega columns through a push-out analysis of eleven 1.2- × 1.2-m mega columns. The bond-slip behavior of CFST mega columns with and without mechanical connectors, including shear studs, rib plates, and connecting plates, is studied. The finite-element results indicate that the mechanical connectors substantially increased the maximum bond stress. Among the analyzed CFST mega columns, those with closely spaced shear studs and rib plate connectors with circular holes exhibited the highest bond stress, followed by plate connectors and widely spaced shear stud connectors. In the case of shear stud connectors, the stud diameter and spacing influenced the bond behavior more than the stud length. As the stud spacing decreased, the failure mode shifted from studs shearing off to outward buckling of the steel tube.

Prospective randomized trial of metal versus resorbable plates in surgical stabilization of rib fractures.

Surgical stabilization of rib fractures has gained popularity as both metal and resorbable plates have been approved for fracture repair. Is there a difference between metal and resorbable plate rib fixation regarding rib fracture alignment, control of pain, and quality-of-life (QOL) scores (Rand SF-36 survey)? Eligible patients (pts) included 18 years or older with one or more of the following: flail chest, one or more bicortical displaced fractures (3-10), nondisplaced fractures with failure of medical management. Patients were randomized to either metal or resorbable plate fixation. Primary outcome was fracture alignment. Secondary outcomes were pain scores, opioid use, and QOL scores. Thirty pts were randomized (15 metal/15 resorbable). Total ribs plated 167 (88 metal/79 resorbable). Patients with rib displacement at day of discharge (DOD) metal 0/14 (one pt died, not from plating) versus resorbable 9/15 or 60% ( p = 0.001). Ribs displaced at DOD metal 0/88 versus resorbable 22/79 or 28% ( p < 0.001), 48% in posterior location. Patients with increased rib displacement 3 months to 6 months: metal, 0/11 versus resorbable, 3/9 or 33% ( p = 0.043). Ribs with increased displacement 3 months to 6 months metal 0 of 67 versus resorbable 6 of 49 or 12.2% ( p < 0.004). Pain scores and narcotic use at postoperative Days 1, 2, 3, DOD, 2 weeks, 3 months and 6 months showed no statistically significant difference between groups. QOL scores were also similar at 3 months and 6 months. Trauma recidivism in outpatient period resulted in fracture of resorbable plates in two pts requiring a second surgery. Metal plates provided better initial alignment with no displacement over time. Clinical outcomes were similar regarding pain, narcotic use, and QOL scores. Routine use of resorbable plates for posterior rib fractures is not warranted. Lateral repairs were technically most feasible for using resorbable plates but still resulted in significant displacement. Resorbable plates may not maintain rib alignment when exposed to subsequent injury. Therapeutic/Care Management; Level II.

Rigidity of Circular Plates with Radial Ribs, Placed on One Side, Neglecting the Influence of Welding Seams. Nerves with Constant Thickness and Height Along the Entire Length

Abstract The present study refers to a plane circular plate, provided with equidistant radial ribs, placed on one side (fig. 1), these having the same geometry of the cross section (thickness and height) along their entire length (fig.2). There is a change in the position of the neutral fiber of the ribbed plate and also in its bending rigidity, along the radius of the plate, in different cases.

Flexural capacity of steel-UHTCC (ultra-high toughness cementitious composite) bridge deck considering different shear connection degrees

Due to the excellent cracking prevention behavior of ultra-high toughness cementitious composite (UHTCC), the stud number and reinforcement ratio of composite bridge decks could be reduced, and hence the fatigue properties could be improved. In this study, a theoretical model was proposed to predict ultimate flexural capacity of steel-UHTCC composite bridge decks with different shear connection degrees. To evaluate the accuracy of the theoretical model, 10 examples were designed for finite element (FE) validation and parametric study, and the results indicated that the theoretical model can predict the ultimate flexural capacity of steel-UHTCC composite bridge decks with satisfactory accuracy. Then, quantitative analysis was conducted to reveal the effect of key design parameters on the ultimate flexural capacity. The design parameters involved in the parametric study included: (1) normalized stud number; (2) shear span length; (3) thickness of UHTCC slab; (4) reinforcement ratio; and (5) the number of longitudinal plate ribs. The reasonable range of the normalized stud number in a shear span can be determined between 0.5 and 1 in practical design and increasing of longitudinal reinforcement ratio has limited effect on ultimate flexural capacity of steel-UHTCC composite bridge decks.

Research on the Rational Design Method of Strength Reinforcement for Thin-Walled Structure Based on Limit Load Analysis

Thin-walled structures subjected to internal or external pressure usually need to be reinforced with ribs. The design of ribs is generally based on experiences in engineering, and the results are often very conservative. In this paper, an approach for the rational design of reinforced ribs on thin-walled structures is proposed based on the limit load analysis method, maximizing the limit load of the reinforced thin-walled structure or minimizing the weight of the reinforced ribs. Firstly, the limit load numerical analysis was conducted to study rib forms at the continuous and discontinuous regions of the structure and find the rational ribs which provide the most effective reinforcement for the structure. Then, using the proposed rib forms, an engine test cabin was re-designed based on the limit load analysis to verify the feasibility and effects of the rib design. The engine test cabin after the redesign of the rib plate can reach 98% of the limit load of the original test cabin while the weight of reinforcing ribs is only 62% of the weight of the original ones, which means that the reinforcement design approach based on the limit load analysis method and the rib forms proposed in this paper is effective and feasible, and can achieve a structural lightweight design.

Effects of Stiffener Type on Fatigue Resistance of Steel-UHPC Composite Bridge Decks

Recent research showed that ultrahigh-performance concrete (UHPC) and orthotropic steel bridge decks could be integrated to form steel-UHPC composite sections offering superior load-carrying capacity and fatigue resistance. This study investigates the effects of longitudinal stiffener types on the fatigue resistance of steel-UHPC composite sections. Three types of longitudinal stiffeners were compared, including U-ribs, bulb flat ribs, and plate ribs. Finite element analysis and full-scale fatigue tests were performed to investigate the load-carrying capacity and fatigue resistance of the composite bridge decks with different stiffeners. Besides, the proposed steel-UHPC composite bridge decks were compared with conventional orthotropic steel decks. The results show that steel box girders with bulb flat rib composite deck have reasonable fatigue resistance, construction efficiency, and economic benefits. This study is expected to promote the design and evaluation of economic steel-UHPC composite bridge decks to achieve higher mechanical performance and long-term durability.

Time-dependent performance of ribbed plates on multi-layered fractional viscoelastic cross-anisotropic saturated soils

The ribbed plate is divided into the rib-beams and the plate, in which the rib-beams are analyzed by the cross-beam theory, and the plate is assumed to be a Mindlin plate. The rib-beams and the plate are coupled to obtain the FEM stiffness matrix equation of the ribbed plate. The extended precise integration solution of multi-layered cross-anisotropic saturated soils with the fractional viscoelastic model is used as a fundamental solution of the BEM to obtain the soil stiffness matrix on the plate-soil interface. By introducing the compatibility conditions at this interface, the interaction equation between the soils and ribbed plate is achieved. Finally, by comparing the results from this theory and those from existing literatures and ABAQUS, the correctness of this method is proven, and the effects of the height and the layout of the rib-beams on the time-dependent behavior of ribbed plates on multi-layered fractional viscoelastic cross-anisotropic saturated soils are discussed.

Energy harvesting in diesel engines to avoid cold start-up using phase change materials

In diesel engines, a significant amount of energy is wasted to the environment by the exhaust gases and coolants. In this study, a new design of the exhaust waste heat recovery (WHR) heat exchanger is proposed to preheat the intake air before supplying it into a diesel engine at the cold start-up conditions. The heat exchanger is designed of ribbed plates containing paraffin wax phase change material (PCM). This PCM is used to store the thermal energy coming out from the engine during the operation for later use in cold start-up conditions. A numerical model is developed and validated with the experimental results in the literature. The effect of different design conditions along with various operating conditions is evaluated. The influences of ribs height and spacing, engine rotational speed, and intake air temperature on the thermal energy storage were evaluated. Based on the results, it can be concluded that the highest thermal performance was obtained at a rib gap of 90 mm and a rib height of 7.5 mm. Through the warming-up process, in less than 1 min, the cold intake air temperature can be increased from 273 to 302.2 and from 283 K to 300.7 K. This results in overcoming the cold start-up difficulties, specifically in icy weather, and delivers preheated air to the engine after 1 min.

INFLUENCE OF DESIGN FEATURES OF RELATIONSHIPS ON THE STRESS STATE OF REINFORCED CONCRETE FLOOR SLABS

The article shows the influence of the design features of the bonds on the stress state of reinforced concrete floor slabs. Resolving equations for the calculation of plates are presented. A numerical calculation is made for several variants of fixing smooth and ribbed plates and graphs of changes in internal forces depending on the stiffness characteristics of the bonds are presented.

Eigenvalue Analysis and Impact Response Analysis for T-shaped Structures with New Acoustic Black Hole Including Residual Thickness Supported by Nonlinear Concentrated Springs

This paper describes analysis using finite element method with Model Strain Energy Method for steel structures having a T-shaped cross section supported by nonlinear concentrated springs under impact load. An edge of the rib plate in the T-shaped structure has an Acoustic Black Hole with residual thickness. A viscoelastic damping layer is covered on the acoustic black hole. Finite element for the nonlinear springs with hysteresis are expressed and are connected to the T-shaped structures modeled by linear solid finite elements in consideration of complex modulus of elasticity. We calculated modal loss factors and transient responses using the eigen modes including coupled motions between the non-linear springs and the T-shaped structures. From the dominant eigen modes and the time histories, we clarified effects of an Acoustic Black Hole with residual thickness and nonlinear springs on the nonlinear damped responses.

Biomechanical study of embracing and non-embracing rib plates.

The study was carried out to explore the biomechanical properties of embracing and non-embracing rib plates. Forty-eight adult cadaver rib specimens were divided randomly into six groups: three fixation model groups were made using embracing plates (two pairs of equals on both sides of the broken end), and the other three groups were fixed with a pre-shaped anatomical plate (three locking screws on each side of the end were equally spaced). The biomechanical properties of these models were analyzed using non-destructive three-point bending tests, non-destructive torsion experiments, and destructive axial compression tests. In this study, the gap of fracture ends was widened in embracing plate group in the non-destructive three-point bending experiment. No change in the fracture ends was detected in the pre-shaped anatomical plate group. The bending stress of the pre-shaped anatomical plate group was significantly enhanced at the 2-12 mm displacement points (p < 0.05). Moreover, there was no significant difference in torque noticed between the two groups in the torsion experiment (p = 0.082). In the destructive axial compression experiment, the load index of the two groups were higher than the normal physiological load, suggesting that both materials could provide sufficient strength for rib fractures. The pre-shaped anatomical plate displayed more reliable attachment in terms of stability, bending, and load. Our results indicated that the embracing plate has the advantage of fretting at the fracture end.

Band Gaps in Metamaterial Plates: Asymptotic Homogenization and Bloch-Floquet Approaches

In this work, we study the transversal vibration of thin periodic elastic plates through asymptotic homogenization. In particular, we consider soft inclusions and rigid inclusions with soft coatings embedded in a stiff matrix. The method provides a general expression for the dynamic surface density of the plate, which we compute analytically for circular inclusions or numerically for two-way ribbed plates. Through asymptotic homogenization, we find that band gaps related to in-plane propagating transversal waves occur for frequency intervals in which the effective surface density is negative. The same result is obtained via an asymptotic analysis of the Bloch-Floquet problem on a unit cell, showing the equivalence of the two approaches. Finally, we validate the method by comparing in several examples the predicted band gaps with those obtained from numerical Bloch-Floquet analyses on the real unit cell.

APPLICATION OF THE MAPLE PACKAGE FOR CALCULATING THE RIBBED PLATE FOR STRENGTH, TAKING INTO ACCOUNT THE DISCRETE LOCATION OF THE RIBS

This paper presents an analytical calculation of the stress-strain state of a ribbed plate supported by a cross system of stiffeners. The calculation was carried out by the Ritz method using the Maple mathematical package

Numerical assessment of thermal performance of heated air duct with novel arc profile ribs in non-interrupted arrangement

The use of roughness elements in the form of recurring ribs have been established to be a proficient technique of improving the thermal performance of the heated air ducts. In the present research work, the numerical assessment of the thermal performance of arc profile ribs arranged in a non-interrupted arrangement under forced convection has been presented. The ribs are attached to the bottom side of the heated air duct. The key geometrical parameters examined are a ratio of pitch of the rib to the height (p/y = 4–9), a ratio of the height of the rib to arc radius of the rib (y/r = 0.75–1), a ratio of the height of rib to the height of the duct (y/Y = 0.06–0.1) and Reynold’s numbers (Re) in between 12,270 and 36,810. It is revealed from the numerical evaluation that the novel arc profile ribs placed on the plate aids to encourage the level of turbulence which consequences in the improvement of the heat transfer. The thermal performance indicative parameters such as heat transfer improvement factor (HTIF), friction factor ratio (FFR), and overall thermal performance (OTP) are studied against variation of Reynold number and key geometrical parameters. The Nusselt number, friction factor for the ribbed plate represent an improvement of about 45%, 41% respectively as compared to the plain plate. The findings from the present work are compared with earlier published work for the same range of Re. The magnitude of OTP reported in the present work is higher than unity. Therefore this can be considered as one of the effective techniques for improvement of thermal performance of heated duct under forced convection.

Mid-high frequency vibration attenuation properties of periodic U-rib plates: Numerical modeling and scale specimen testing

Periodic U-rib plates are applied widely in steel box girders because of their light weight and high strength, but their associated vibration response and noise pollution are significant. The widely used statistical energy analysis (SEA) is an effective method to calculate structural vibrations at mid-high frequencies, but this approach does not consider indirect coupling mechanisms, which lead to errors. In this paper, the advanced statistical energy analysis (ASEA) approach is introduced to reduce vibration prediction errors in periodic U-rib plates for the first time. A scale U-rib plate dynamic test includes modal tests and the difference of energy level (DEL), which verifies the accuracy of finite element (FE) calculations. Thus, the ASEA algorithm was verified to be more accurate than the SEA and is used to calculate vibrations for actual U-rib plates. The results show that the ASEA is more accurate than the SEA mainly because it considers indirect coupling between non-adjacent sub-systems. The results calculated from the SEA have low errors within 5 dB when the distance between the sub-system and source sub-system is smaller than three times the U-rib distance. For larger frequencies, the energy discrepancy increases gradually from 100 to 2000 Hz, and the bending wave passes through each U-rib, which causes a 1.0–22.6 dB energy discrepancy. The influences of the rib shape and plate thickness are studied, and some suggestions are given.