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Heat exchangers, as essential devices for facilitating heat transfer, have found a variety applications in various industries. However, the occurrence of corrosion-related failures in real-world scenarios remains a prevalent problem that can lead to catastrophic incidents. This paper investigates the problem of corrosion perforation on the outlet flange of a heat exchanger in a sour steam stripper from a petrochemical company. Failure analysis was performed using physical testing and chemical analysis, metallographic examination, microscopic observation, and energy spectrum analysis. Intergranular corrosion experiments and flow calculations were performed to verify the analysis. The results indicate that the main cause of the flange corrosion perforation was the formation of a highly concentrated NH4HS aqueous solution during the cooling process of the NH3, H2S, and water vapor in the fluid passing through the heat exchanger, and the velocity was too high, which triggered alkali-sour water washout corrosion. To prevent the recurrence of similar corrosion perforations, recommendations for material and process optimization are proposed to effectively reduce the safety production risks in refinery units and provide valuable information for the safe long-term operation of a sour steam stripper. [ABSTRACT FROM AUTHOR]

An accurate and reliable estimation of the transformation matrix between an optical sensor and a robot is a key aspect of the hand–eye system calibration process in vision-guided robotic applications. This paper presents a novel approach to markerless hand–eye calibration that achieves streamlined, flexible, and highly accurate results, even without error compensation. The calibration procedure is mainly based on using the robot's tool center point (TCP) as the reference point. The TCP coordinate estimation is based on the robot's flange point cloud, considering its geometrical features. A mathematical model streamlining the conventional marker-based hand–eye calibration is derived. Furthermore, a novel algorithm for the automatic estimation of the flange's geometric features from its point cloud, based on a 3D circle fitting, the least square method, and a nearest neighbor (NN) approach, is proposed. The accuracy of the proposed algorithm is validated using a calibration setting ring as the ground truth. Furthermore, to establish the minimal required number and configuration of calibration points, the impact of the number and the selection of the unique robot's flange positions on the calibration accuracy is investigated and validated by real-world experiments. Our experimental findings strongly indicate that our hand–eye system, employing the proposed algorithm, enables the estimation of the transformation between the robot and the 3D scanner with submillimeter accuracy, even when using the minimum of four non-coplanar points for calibration. Our approach improves the calibration accuracy by approximately four times compared to the state of the art, while eliminating the need for error compensation. Moreover, our calibration approach reduces the required number of the robot's flange positions by approximately 40%, and even more if the calibration procedure utilizes just four properly selected flange positions. The presented findings introduce a more efficient hand–eye calibration procedure, offering a superior simplicity of implementation and increased precision in various robotic applications. [ABSTRACT FROM AUTHOR]

This study aims to describe a new technique of indirect cyclopexy in the treatment of cyclodialysis. Cases who had cyclodialysis for more than 3 h of extent and were resistant to medical treatment underwent flanged prolene cyclopexy (FPC) technique. Five cases were included in this study. Mean duration between the initial surgery and FPC was 4.6 ± 4.3 months. Hypotony maculopathy was present in all cases. All cases underwent FPC in combination with pars plana vitrectomy and silicone oil injection. Circumferential FPC was applied in four cases, while focal FPC was performed in one case. Postoperatively, no complications occurred, visual acuity increased in four cases, and cyclodialysis closed in all cases. In the follow-up, silicone oil was removed in three cases, but silicone oil could not be removed in two cases with ongoing hypotony. Preliminary results showed that FPC is a promising technique in the surgical treatment of cyclodialysis. [ABSTRACT FROM AUTHOR]

The local buckling of I-section beams is investigated with the flange–web interactions taken into account. Using numerical results employing the finite element method and a semi-analytical method, the flange–web interactions of I-sections and their effects on the buckling stresses are explored and discussed. Simple approximate solutions for the buckling coefficients of the web and compressive flange are developed using the energy method, and they are refined using the numerical results. Using the simple solutions for buckling coefficients, the limits for the width-to-thickness ratio of the compressive flange and web of I-section beams are then proposed. Comparisons with the results of existing solutions and provisions in design codes imply that the proposed solutions are superior in predicting the limits for width-to-thickness ratios, and they are capable of accounting for the flange–web interactions at the local buckling of I-section beams. [ABSTRACT FROM AUTHOR]

In some design cases, such as in castellated beams, cellular beams, or steel beams with expanded web, it is advantageous to strengthen and enhance the performance of steel beams by increasing the web depth. However, expanding the web of a steel beam is a unique engineering strategy. This modification not only enhances its ability to bear heavy loads but also reduces any bending or flexing while enabling longer distances between supports. The expanded steel beams can be achieved by making a horizontal cutting in the steel beam web and then adding an increment plate (with the same web thickness), called spacer plate, between the two halves of the web sections, thus improving stiffness and strength. To evaluate the behavior of such beams, nine specimens of HEA steel beams with expanded web ratios of 150%, 200%, and 250%, and one specimen as a reference beam, were fabricated. The specimens were evaluated under two-point load over a clear span length of 280 cm. From the experimental work it was found that for steel beams with expanded web that have 18 openings with 80 mm, the beams with an expansion ratio of 150% had the best performance according to load-deflection behavior with a reduction in load capacity by only 11%. Additionally, the beams with expansion ratios of 200% and 250% had no economic viability according to the analysis of load-deflection behavior with a reduction in load capacity by 49% and 62%, compared with the solid expanded steel beam with the same expansion ratio. For the second type of steel beam with expanding web with 9 openings of 160 mm width, the beams with expansion ratios of 200% and 250% were observed to perform better than the first type with a reduction in load capacity by 28% and 50%. Using larger opening width and a smaller opening number is considered the best option for beams with expansion web ratios of 200% and 250%, while on the contrary, using smaller opening width and higher numbers seems to be a better option for beams with 150% expansion web ratio. Expanding the depth of a steel beam provides design flexibility, reduces deflections, and allows for longer spans. These benefits enhance material efficiency and open up new architectural possibilities. [ABSTRACT FROM AUTHOR]

This numerical study presented and analysed a new technic of castellated steel beam "Alternate Closed Opening Castellated Beam" applied only to double steel channel shapes connected back to back. ABAQUS/2019 program employed to create modelling and analysis for two groups of models with the same length and conditions of loading. The first group has three noncomposite beam models: the first reference model without castellated, the second model with normal castellated and the third model with new castellated, also the second group has three composite beam models: the first reference model without castellated, second model with normal castellated and the third model with the new castellated. According to the analysis results; For the first noncompsite group, ultimate load for the second and third models increased by 8.84% and 16.63%, respectively, compared to the reference model, with local buckling in the top flanges under concentrated loads and lateral-torsional buckling as the failure modes. For the second composite group, the ultimate load for the second and third models increased by 41.83% and 62.19%, respectively, compared to the first reference model, with the flexural mechanism as the main failure mode. This enhancement in the load-carrying capacities of the new Alternate Closed Opening Castellated Beams is due to the limit states mode of failures resulting from web holes. [ABSTRACT FROM AUTHOR]

In this contribution, a new forming method is presented for high-strength steel sheet metal materials called Transversal Compression Drawing (TCD). For TCD, the blankholder of the conventional deep drawing process is replaced by sliders introducing a vertical force along the blank edge. Compared to conventional deep drawing, compressive stresses are thereby superimposed in the flange area of the sheet metal material, reducing the springback of formed components and the forces required during the process. Proof of this is provided here on the basis of numerical investigations in which conventional deep drawing and TCD are compared using the example of an "S-Rail" component made from DP980. Results of these investigations reveal that with TCD a maximum reduction in springback by more than 5 mm is achieved, leading to an improvement in the component´s overall shape accuracy of more than 55%. Furthermore, frictional work is decreased by − 6.92 kJ/kg, resulting in an overall reduction of maximum forming forces by 67.4%. Besides, TCD enables a trim-free net shape forming of the final part contour in a single operation and an increased material utilization of 4.5% from coil to part. Not least, no sheet thinning occurs with TCD, whereas a maximum thinning of 12% is observed with the conventional deep drawing process. [ABSTRACT FROM AUTHOR]

The article deals with an innovative, but not widely used type of joining of aluminum pipes through experiments. The joints are formed by plastic forming. The process is carried out in one step using the principle of pipe expansion, in order to bring the mating surfaces of the two pipes into a suitable position for the subsequent joining, which is created by means of plastic instability and simultaneous pressure flanging. Experimental tests were carried out with the tools designed to create most suitable joints. The length of the plastically formed pipe sections involved in the joint, the angle of the sharpened pipe ends, and the thickness of the formed joints were analyzed. One of the main goals of this study is to determine the proper joining parameters, such as tool distance or edge tapering for further investigations. As per the test results, it can be stated that the technology is suitable for joining aluminum tubes in a cost-effective way, and based on the promising strength results, further investigations will be conducted. [ABSTRACT FROM AUTHOR]

In this study, narrow (edge) wall standing wave slotted waveguide antenna design is proposed. This antenna operates at 2.812 GHz in S frequency band. Also, the design equations and slot characterization method are given in this study. This antenna is designed with two flanges to shape the elevation pattern and to increase the antenna gain. This antenna provides low cross polarization without using any polarizer or any other structure. The designed antenna is suitable for high gain and high-power applications. The performance of the proposed design is examined with simulations and verified with measurements. [ABSTRACT FROM AUTHOR]

The behavior of steel bolted connections is a complex structural problem which involves various factors such as material nonlinearity, large deformation and contact. The investigation of this behavior is one of challenging subjects in structural analyses. Unlike other structural modelling, the connections of bolted structures involve a large number of contacts, which are critical to the behavior of the joints. This paper focuses on investigating the behavior of a type of the external diaphragm which is used in rectangular hollow section column-to-beam bolted connections. The creation of a reliable finite element model is a primary aim of this research. The ABAQUS finite element package is used to simulate the experimental behavior, and three highly complex 3D finite element models are created, accounting for material nonlinearly, large deformation and contact behavior involved in the models. The connection models have been analyzed under some loading conditions up to failure. Comparisons with experimental data show that the models have high levels of accuracy, and these models may be used to gain an insight into important issues such as the connection tying force capacity of an external diaphragm, bolt and plate bearing behavior, and bolt shearing. [ABSTRACT FROM AUTHOR]

Bath galvanized substructures for rear‐ventilated façades – part 1 Thin‐walled steel components (0.8–2.5 mm) for substructures according to DIN 18516‐1 can be produced using galvanisation. Brackets and support profiles remain warp‐free, the thickness of the zinc layer is above the standard acc. to DIN EN ISO 1461. Flanging on the edges of the holes in the brackets and lateral edging increase the load‐bearing capacity, as do increasing sheet thicknesses. Load‐bearing profiles are also strengthened by lateral edging; U‐ and hat‐profiles are on top. Experimental tests in the climatic chamber revealed a gradation of the perforated brackets; the most favourable design is the bracket with three slotted holes. Thermal and mechanical tests have proven that galvanized components represent a static, thermal and economical alternative to commercially available substructure systems. [ABSTRACT FROM AUTHOR]

Surface settlement is considered a key indicator in the pipe jacking procedure of the steel tube slab (STS) pipe-roofing method. Commonly, the existing equations for this safety indicator are applied in the process of measuring surface settlement caused by the pipe with circle or rectangle cross sections. This paper proposes calculation methods for the surface settlement of a circular steel pipe with flange plates based on the modified Mindlin solution considering pipe–soil interaction and the influence of flange plates. The proposed equations in this paper are applied to calculate the surface settlement for the actual pipe jacking engineering in Shenyang, China, and the calculated results fit well with the field monitoring values. This paper analyzes the main geometric parameters affecting surface settlement, including the orientation of flange plates and pipe specification. Simultaneously, this paper obtains the mathematical relationships between the surface settlement and the geometric parameters, providing a theoretical prediction method for actual pipe jacking construction of the STS pipe-roofing method. The development of metro construction has become one of the indications of urban progress. How to build metro projects efficiently and safely has become one of the main problems of underground engineering. The steel tube slab (STS) pipe-roofing method is a new method of constructing urban underground space, which not only enhances the sideways stability of the conventional pipe-roofing system but also effectively regulates the subsidence of the ground during underground digging, thereby augmenting both the horizontal and the vertical load-bearing capabilities. This method has already been efficiently employed in the construction of the subway stations of Shenyang Metro Line 9 and Line 10. This paper proposes calculation methods for the surface settlement of a circular steel pipe with flange plates based on the modified Mindlin solution considering pipe–soil interaction and the influence of flange plates. This paper analyzes the main geometric parameters affecting surface settlement, including the position of flange plates and steel pipe diameter. Simultaneously, this paper obtains the mathematical relationships between the surface settlement and the geometric parameters, providing a theoretical prediction method for actual pipe jacking construction of the STS pipe-roofing method. [ABSTRACT FROM AUTHOR]

The design and operation of conventional power plant components is affected by load changes, with the balancing of renewable energy generation leading to an increase in warm and hot starts. Essential parts of these power plant components are flanges e.g. connecting pipes and turbine housings. While being structural rather simple, many influences affect the functionality of these flanges, like the high-temperature behaviour of the bolt material or the temperature distribution in the components. This paper presents parts of a recently finished research project on different influences on the relaxation behaviour of flanges. To investigate the influence of the bolt material, tests were carried out on a model of an IP turbine flange using martensitic X12CrMoWVNbN10-1-1 and nickel-based Ni80A bolts. Each tests included 2000 h of steady state and 3000 h of transient load with a retightening of the bolts after 1500 h. Exemplary relaxation tests on the X12 material provide additional information towards the observed behaviour in the flange tests. [ABSTRACT FROM AUTHOR]

Fossils referable to the gorgonopsian Gorgonops sp. and to the dicynodont Endothiodon sp. are described from the Permian Madumabisa Mudstone Formation of the Mid-Zambezi Basin of southern Zambia. Specimens of the former taxon conform to recent diagnoses of the genus (e.g., five postcanine teeth, transverse flange of the pterygoid backswept, postorbital bar rugose and moderately expanded), but differ slightly from South African material in some respects (e.g., reduced dentition on the transverse flange of the pterygoid). Fossils of the latter are less complete, but show diagnostic features such as a dentary with numerous teeth, a ventral boss, and a shallow posterior dentary sulcus, oval palatine pads, and a narrow intertemporal region of the skull, although a species-level identification is not currently possible. Although the relevant fossils were never described, a vertebrate fossil assemblage including Endothiodon was previously reported from the Madumabisa Mudstone Formation in northern Zimbabwe (i.e., K5d), suggesting that this biozone was relatively broadly distributed across the Mid-Zambezi Basin. The Mid-Zambezi Basin of southern Zambia was previously demonstrated to host Guadalupian Tapinocephalus Assemblage Zone-equivalent strata, with rhinesuchids, burnetiamorphs, tapinocephalids, and dicynodonts recognized. The recognition of Lopingian Endothiodon Assemblage Zone-age rocks expands the stratigraphic range of vertebrate-bearing horizons in southern Zambia. [ABSTRACT FROM AUTHOR]

Connections play a crucial role in structures, including steel structures, and have a significant impact on the seismic behavior of the structure. One particular type of connection commonly used in steel structures is the Reduced Beam Section (RBS). This connection reduces the moment strength of the beam near the column, which in turn results in less moment being transferred to the column at the final moment. The study involved 30 numerical analyses conducted using ABAQUS to examine two cases. The first case involved investigating a connection with a beam that had a hole in the flange area. The variables examined included the area of the flange holes and the axial force of the column. In the second case, a yield ring was utilized in the flange area of the beam. The radius of the yield ring was considered as a variable in six different cases. Equations for calculating the maximum strength moment and analyzing the linear region of a beam were presented in the study. The yielding damper must yield earlier than other members, and an equation was provided to ensure that it does. Finally, the cyclic behavior of the two models was also compared. Numerical analysis revealed that if the area of the flange holes is half that of the beam flanges, the beam's strength does not significantly decrease with increasing axial force. The elastic stiffness and ductility of the SRD-equipped connection were higher than the RBS model, with the SRD model achieving 1.8 and 2.6 times greater ductility and elastic stiffness, respectively, in the most optimal state. [ABSTRACT FROM AUTHOR]

Recently, in the field of structural health monitoring, the detection of bolted connection looseness through percussion-based method and machine learning technology has received much attention due to the advantages of removing the requirement of sensor installation and potential for automation. However, there are few such research which are performed in the underwater environment. The paper proposes a new method, Feature-reduced Multiple Random Convolution Kernel Transform (FM-ROCKET), to identify the looseness level of the underwater bolted connections based on the percussion-induced sound (audio signal). By integrating deep learning (DL) and shallow learning, the FM-ROCKET model uses the 1D convolutional layer (a DL method) to extract features from the percussion-induced audio signal and adopts the rigid classifier (linear classifier, a shallow learning method) to classify the features. Five different preload levels of the bolted flange are considered. A hammer is utilized to tap the flange surface and the continuous percussion-induced audio signal is collected by a smartphone in an underwater environment. After the audio signal segmentation, single-hit audio signals are fed into the FM-ROCKET model. To verify the effectiveness of the proposed method, three case studies are conducted on two flanges. In case study I, the proposed method slightly outperforms other DL-based methods under different training/test splitting ratios. In case studies II and III, the proposed method is far more effective than other DL-based methods on independent and different test sets. The results demonstrate the superiority of the FM-ROCKET model in the underwater detection of bolted flange looseness. To the best of our knowledge, this article is the first attempt to address the detection of bolted flange looseness in the underwater environment by combining percussion-based method, DL, and shallow learning. [ABSTRACT FROM AUTHOR]

For the drawing of small-sized parts, open-type presses with double action are preferred, as the processing is carried out under better conditions than on those with single action. This paper presents the eccentric mechanical press that was used for drawing small cylindrical parts made of A3K strip. For the smooth progress of the deformation process, it was necessary to know the magnitude and variation of force during the working stroke. The press was equipped with the drawing die onto which a dynamometric sensor was mounted, allowing both the measurement of the force required for deformation and the retention pressure of the flange. An inductive displacement transducer was mounted on the ram of the press. The signals collected from the transducer and sensor were amplified by an electronic strain gauge and transmitted to an oscillograph for visualization. The parts were produced using active elements of different sizes while maintaining the same clearance value between them. [ABSTRACT FROM AUTHOR]

In this paper, a new technology for on-orbit cold forming of space truss rods is proposed. For the cold roll forming process of asymmetric cross sections of thin strips, the effects of roll gap and roll spacing on the forming of asymmetric cross sections of strips were investigated using ABAQUS simulation + experiments. The study shows the following. When forming a strip with a specific asymmetric cross section, the stresses are mainly concentrated in corners 2/4/6, with the largest strain value in corner 2. With increasing forming passes, when the roll gap is 0.3 mm, the maximum equivalent strain values are 0.09, 0.24, 0.64 sequentially. Roll gaps of 0.4 mm and 0.5 mm equivalent strain change amplitude are relatively similar, and their maximum equivalent strain values are approximately 0.07,0.15, 0.44. From the analysis of the stress–strain history of the characteristic nodes in corners 2/4/6, it can be seen that the stress and strain changes in the deformation process mainly occur at the moment of interaction between the upper and lower rollers, where the stress type of node 55786 shows two tensile types and one compressive type, the stress type of nodes 48594 and 15928 shows two compressive and one tensile type, and the strain of the three nodes is in accordance with the characteristics of plane strain. When the roll gap is about 0.4 mm, the forming of the strip is relatively good. With increased roll spacing, the strip in the longitudinal stress peak through the rollers shows a small incremental trend, but the peak stresses are 380 Mpa or so. When the roll spacing is 120 mm, the longitudinal strain fluctuation of the strip is the most serious, followed by the roll spacing at 100 mm, and the minimum at 140 mm. Combined with the fluctuation in strip edges under different roll spacings, manufacturing cost and volume and other factors, a roll spacing of 100 mm is more reasonable. It is experimentally verified that when the roll gap is 0.4 mm and the roll spacing is 100 mm, the strip is successfully prepared in accordance with the cross-section requirements. When the rolling gap is 0.3 mm, due to stress–strain concentration, the strip is prone to edge waves in forming. The top of corner 2 of the flange triangular region is susceptible to intermittent tear defects, and the crack extension mechanism is mainly based on the cleavage fracture + ductile fracture. [ABSTRACT FROM AUTHOR]

The T-shaped tube is a common component in aviation pipeline systems and has broad application prospects. However, the severe wall thickness thinning has been the bottleneck problem restricting the application of T-shaped tubes. In order to avoid rupture due to excessive thinning and improve the forming quality, a new rubber compound-forming method combined with the flanging and bulging of the T-shaped tube using a prefabricated hole is proposed. The optimization model of the prefabricated hole is established based on the geometric analysis method and the incremental finite element method. The optimal prefabricated hole is achieved through two iteration optimizations. The experiments for the compound-forming method are carried out to reveal the forming height and the wall thickness distribution mechanism. Both the simulation and experiment results are in good agreement, the numerical simulation results with the optimal prefabricated hole are that the maximum thickening rate is 45.60% and the maximum thinning rate is 22.93%, and the experimental results with the optimal prefabricated hole are that the maximum thickening rate is 48.67% and the maximum thinning rate is 16.67% which are satisfied with the requirements of practical production with the maximum thickening rate no more than 50% and the maximum thinning rate no more than 30%. The new compound-forming method using the prefabricated hole could effectively avoid fracture on the branch's top. The comparison results are further verified to be the correctness of the prefabricated hole optimization model and the effectiveness of the new compound-forming method. [ABSTRACT FROM AUTHOR]

In the production process of the giant tire, the tire unloader needs to clamp and flip the tire, and the tire has a large inertia force, easy to cause vibration and lead to the failure of bearing parts, etc., then the flange is needed to play a fixed role. therefore, the rationality of flange design for the use of safety and service life are very important. For this reason, this paper simulates the flange connected to the tire unloader to obtain its stress history data, at the same time through genetic algorithm structure optimization analysis was carried out on the flange, it is concluded that the influence of structure parameters on the life of flange, and flange for structure optimization, get the optimized flange fatigue life 71 % increase compared to the original plan. The weight is reduced by 0.9 %, and the mechanical properties of the optimized flange are better. [ABSTRACT FROM AUTHOR]

A replacement for Amelia Earhart Bridge, carrying Highway 59 across the Missouri River (MO, USA), has been constructed. Interactions between the flow around this bridge and two existing bridges adjacent to the new bridge had the potential to create large scour holes. As the original bridge needed to remain open during the construction of its replacement, a scour study was performed to determine the placement of the piers. The new bridge uses prestressed concrete bulb T-girder spans for the approaches and one 160.6 m (527 ft) steel network tied arch for the main navigation span. The bridge was designed in 2008 and was one of the first modern tied arch bridges in the USA to use internal redundancy for fracture-critical members using bolted angles at the intersection of the tie girder webs and flanges. Due to vertical clearance constraints, the tied arch contains a framed-in-floor system to minimise the depth of the structure. This also required a specific slab pouring sequence to relieve the elongation effects of the tie girder during construction. This signature structure opened to traffic in 2012 and project completion occurred in summer of 2013. This paper focuses on the pier placement relating to scour concerns and the design of the tied arch span. [ABSTRACT FROM AUTHOR]

The fatigue life analysis of radial Cylindrical Roller Bearings (CRBs) is performed by considering the effects of the roller end-flange construction. A NUP-type CRB with the conical flange and the rollers having spherical ends is considered under various combined loads. The effect of the variation of the flange angle on the bearing life is addressed. The slicing method is employed to obtain bearing internal load distribution, and the elastic half-space method is used to calculate contact pressures and subsurface stresses, which are necessary for bearing life calculations. For the combination of radial and axial loading, it's observed that the bearing life decreases up to a certain value of the flange angle, and the changes in the life are minimal after a certain flange angle. For high misalignment angles of the inner ring with radial loading, the results show that the predicted life decreases until a particular flange angle and then increases with increasing flange angle. The change in the bearing life depending on the flange angle is mainly attributed to the change in the roller tilt angle versus the flange angle. [ABSTRACT FROM AUTHOR]

This paper reports comparative studies of the fire behavior of partially encased composite beams (PECBs), slim-floor composite beams (SFCBs), and fully encased composite beams (FECBs) using validated numerical models. The effects of parameters such as load ratio, concrete slab width, concrete and steel strength, and section dimension of the steel beam were considered. The findings indicate that the mechanical behavior of PECBs, SFCBs, and FECBs undergoes four distinct phases when exposed to elevated temperature, namely an elastic phase, an elastic-plastic phase, a plastic yielding phase, and a plastic instability phase. The failure criterion proposed by ISO 834 is more appropriate for predicting the failure of PECBs, SFCBs, and FECBs than those proposed by BS 476-20 and ASTM E119-18. The failures of SFCBs and FECBs under fire were both demonstrated to be the crushing of concrete and yielding of steel beam, whereas when PECBs fail, the steel beam yields, but whether the concrete of PECBs is crushed is determined by the load ratio. At elevated temperatures, the web of PECBs and SFCBs yields earlier than the lower flange. Additionally, the lower flange of PECBs and SFCBs has the potential to convert from a state of tension to compression. Increasing the web height and thickness or decreasing the load ratio can prolong the duration of plastic yielding phases and plastic instability phases, thus improving the fire resistance of PECBs, SFCBs, and FECBs. In addition, the fire resistance of PECBs, SFCBs, and FECBs are barely affected by the concrete slab width, steel strength, and shear connection degree. Although PECBs and SFCBs both have good fire resistance, additional measures such as welding the reinforcement to the web or applying a fire protection layer to the lower flange are required to meet 2-h fire resistance at a load ratio of 0.4. Moreover, FECBs can achieve 2-h fire resistance even if the load ratio is up to 0.8. [ABSTRACT FROM AUTHOR]

The brittle behavior traditional directly welded connections of steel beams to concrete-filled steel tube columns is caused primarily by excessive out-of-plane deformation of the tube walls at the level of the beam tension flange. To address this issue, this study proposes a reference connection that involves fillet welding a built-up steel beam directly to the corner of a diamond-shaped concrete-filled steel tube (DCFST) column. Two options are suggested for enhancing the seismic performance of the reference connection: a predrilled hole with a 12-mm diameter at the midwidth of each beam flange, or a rib stiffener reinforcement on the outside of each beam flange. The two proposed specimens and a traditional directly welded connection were subassembled and investigated experimentally. The results showed that the reference DCFST connection significantly improved the seismic response of the directly welded connection in terms of initial stiffness, strength, ductility, and energy-dissipating capacity. Specifically, the initial stiffness and strength capacity increased by over 150% compared with that of the traditional connection counterpart. Furthermore, the rib stiffeners contributed to further enhancement of the seismic response by shifting the beam plastic hinge away from the column face. Overall, these findings suggest that the use of DCFST connections is reliable for composite moment-resisting frames (C-MRFs), and the proposed enhancements can improve the seismic performance of these connections significantly. [ABSTRACT FROM AUTHOR]

This paper proposes replaceable buckling-restrained flange cover plates to improve the seismic performance and resilience of steel frame joints. Five full-scale specimens were designed and tested under cyclic loads to investigate the hysteretic performance. The investigated parameters were the core plate thickness (affecting strength ratio α and thickness-gap ratio β) and restraining plate configuration (affecting restraining length ratio λ and restraining plate disconnected position ratio ψ). Numerical models were established using ABAQUS and verified through comparisons with experimental data and phenomena. The results show that the proposed joint can achieve the expected target of buckling-restraint and damage control. [ABSTRACT FROM AUTHOR]

During the Northridge earthquake, extensive brittle failures on the weld zones of the beam bottom flanges in the rigidity connection of steel special moment frames (SMFs) were detected. One of the primary reasons is the high-tensile strain demand created at the beam bottom flange zones due to positive bending. The weak panel zone of the I-section column exhibits more shear deformation, which promotes and accelerates the brittle fracture of the beam bottom flange weld zones. A box-strengthened panel zone can minimize the shear deformation of the panel zone of the I-section column, which may also reduce the inter-story displacement of steel SMFs and enhance their seismic behavior. In order to investigate this fact, in this research we carried out a model test of a steel frame with a box-strengthened panel zone to examine SMFs' seismic performance and inter-story displacement, as well as testing the contribution of panel zone shear deformation to inter-story drift. Numerical methods were then used to investigate the influence of the axial compression ratio and beam-to-column linear stiffness ratio on the effect of shear deformation on the box-strengthened panel zone. Design recommendations are given based on the research results. [ABSTRACT FROM AUTHOR]

To assist the low-cost manufacturing of tanks, a one-step method of marginal-restraint mandrel-free spin forming is therefore proposed in this study for the forming of top covers with flanged holes. With the finite element simulation analysis, three different forming strategies are discussed, and the best spinning process is identified. The proposed forming strategies involve preforming the flanged surface first and then preforming the spherical and flanged surfaces in a subsequent trajectory and is proved to have better forming accuracy. Furthermore, the forming quality of the spun parts is improved and optimized by employing more passes, smaller feed ratios, and larger roller fillet radii. It was experimentally verified that the marginal-restraint mandrel-free spinning one-step method with five passes, a feed ratio of 1 mm/r, and a roller fillet radius of 60 mm for the cylindrical roller can achieve accurate forming of a top cover with a center flange hole. [ABSTRACT FROM AUTHOR]

There has been a growing interest in using large-diameter strands to alleviate congestion by using fewer strands, reduce the total number of girders by increasing girder spacing, increase the span length, and allow shallower girders. While the 2020 AASHTO LRFD Bridge Design Specifications included 17.8-mm (0.7-in.) strands by reference to AASHTO M203, these larger-diameter strands were not used in bridge construction primarily because AASHTO LRFD was silent about the design aspects of members reinforced with 17.8-mm (0.7-in.) strands. The presented multifaceted, multiyear research involved an extensive parametric design case study, nonlinear finite-element analyses, material characterization, component tests, and full-scale girder experiments. This paper focuses on the full-scale girder tests, which were used to examine development length, detailing requirements, and flexural and shear behavior and strength. Experimentally determined development lengths were found to be shorter than those prescribed by the AASHTO LRFD Specification. Flexural and shear strength could be determined using established procedures. The current minimum required amount of confinement reinforcement was found to be sufficient to confine 17.8-mm (0.7-in.) strands. The extension of bottom flange confinement reinforcement was found to be inadequate for cases with partially debonded 17.8-mm (0.7-in.) strands, but extension of bottom flange confinement reinforcement to 1.5d beyond the end of the girder was adequate for cases with no debonded strands. The minimum bottom flange confinement reinforcement required by the AASHTO LRFD Specification must be extended to at least 1.5d beyond the termination of the longest debonded length of 17.8-mm (0.7-in.) strands. [ABSTRACT FROM AUTHOR]

This paper proposes an equivalent 2d model incorporating translational and rotational springs to simulate constraints in the stability analysis of steel plates under in-plane patch loading. The main objective is to develop an equivalent stability analysis of these plates by accurately calibrating the level of constraint provided by the stiffeners and flanges. The calibration involves determining the spring constants of a 2d equivalent plate model to achieve the same linear elastic critical load and buckled shape as a 3d model. The paper uses the buckling coefficient as the objective function to calibrate the translational and rotational springs. The ultimate goal is to effectively replicate the constraint conditions imposed by the flanges and vertical stiffeners within the structure. The proposed simplified method yields results that closely align with those obtained from the original 3d model, incorporating finite-rigidity restraints. [ABSTRACT FROM AUTHOR]

Incorporating T-shaped steel and square steel tubes into a cross shaped concrete column can significantly improve the seismic performance of the cross shaped column. However, the experimental samples are limited, so ABAQUS finite element (FE) analysis method was adopted in this paper to study the seismic performance of this cross shaped column, calculate and verify three specimens in the existing reference. Based on the reliable model, parameter analysis was carried out (25 specimens in total). The results show that the established model has a high degree of coincidence in the hysteretic curve, skeleton curve and failure mode, and the error of ultimate bearing capacity and ductility is within 10%. The configuration of T-shaped steel and square steel tubes inside the cross column can meet the ductility requirements specified in the standard under high axial compression ratio. The ultimate bearing capacity of the cross shaped column increases with the increase of the thickness of the square steel tube, but the ductility deteriorates. The increase in steel tube size increases the strength of the concrete in the core area, and the seismic performance of the cross shaped column was improved. Increasing the thickness of the T-shaped steel flange can better improve the seismic performance of the cross shaped column compared to increasing the thickness of the T-shaped steel web plate. Increasing the height of the specimen will significantly reduce its seismic performance. When the shear span ratio is not greater than 4.1, the ductility can meet the standard requirements. The error of the formula for calculating the compression-bending bearing capacity proposed based on existing calculation methods is less than 5%. [ABSTRACT FROM AUTHOR]

This paper presents the study of a single-sided column–tree connection with a replaceable buckling-restrained cover plate (BRCP) at a bottom flange to achieve rapid postearthquake repair for connections in the presence of concrete slabs. During major earthquakes, the bottom flange core plate of the BRCP yields and dissipates energy, and the connection rotates around the center of the top flange connection plate. The slip and yield moments of the proposed connection were theoretically calculated, and the design principle was proposed. Quasi-static loading tests were performed on four specimens. Moreover, the hysteresis behavior, failure modes, force–deformation hysteresis curves, force–deformation backbone curves, strain responses, energy dissipation capacity, and neutral axis position were obtained. Additionally, the influence of restrained forms, unbonded material, and neutral axis position on the hysteresis performance were analyzed. The results show that the two-piece restraint plate leads to extreme local bending of the core plate, the unbonded material on the restraint plate has little effect on the seismic performance, and the core plate undergoes larger deformation when the neutral axis is close to the top flange. Finally, finite-element models of the test specimens were established and validated using the test hysteretic curves and the failure modes to further investigate the test results. [ABSTRACT FROM AUTHOR]

Single point incremental forming is a flexible sheet forming process that does not require a dedicated punch and die for making products for various applications. However, forming parts at steep wall angles, closer to 90°, using this process poses difficulties due to excessive thinning. The motivation behind this study is to overcome the challenges associated with forming parts at steep wall angles using the single point incremental forming process. Controlling the thickness distribution is a significant challenge that needs to be addressed. Excessive thinning leads to disqualification of design criteria, thereby restricting the process' industrial applicability. In the present work, an improved clamping mechanism along with a multi-stage forming approach is employed to address the issue of excessive thinning. Two strategies were evolved; in strategy 1, an improved clamping mechanism was developed for single stage single point incremental forming, while strategy 2 consists of the improved clamping strategy along with a multi-stage forming approach for a single point incremental forming process. The improved clamping was based on the deep drawing process' blank holding type clamping mechanism in both these strategies. The study aimed to compare the formed components' forming depth and thickness distribution using the two strategies. The result revealed that strategy 2 was more effective, resulting in better thickness distribution in the formed component. The thickness distribution improvement resulted from metal flow from the flange region, owing to the improved clamping strategy, during the single and multi-stage forming at steep wall angles. [ABSTRACT FROM AUTHOR]

As a key component of rail vehicle operation, the running condition of the wheelset significantly affects the operational safety of track vehicles. The wheel diameter, flange thickness, and flange height are key dimensional parameters of the wheelset, which directly influence the correct position of wheelsets on the track, and the train needs to be continuously monitored during the passenger operation. A prediction model for the key parameters of the wheelset is established based on LSTM (long short-term memory) neural network, and real measured data of wheelsets from the Shanghai Metro vehicles are selected. The predicted results of the model are compared and analyzed, and the results show that the LSTM-based prediction model for key parameters of wheelsets performs well, with the mean absolute percentage errors (MAPEs) for wheel diameter, flange thickness, and flange height being 0.08%, 0.42%, and 0.44%, respectively, for the left wheel and 0.07%, 0.35%, and 0.44%, respectively, for the right wheel. The prediction model for the train wheelset parameters established in this paper has a good prediction accuracy. By predicting the key parameters of the wheelset, the faults and causes of the wheelset can be found and determined, which is helpful for engineers to overhaul the wheelset faults, make maintenance plans, and perform preventive maintenance. [ABSTRACT FROM AUTHOR]

For the leakage problem of the sealing surface of the subsea flange connector, the flow factors of the isotropic rough surfaces were used to modify the parallel plate leak model, and the relationship between the film thickness ratio and the leaking rat was established. By using MATLAB and COMSOL software, the contact surface entity was generated, three root-mean-square (RMS) roughness surfaces were analyzed by finite element method at four operating temperatures, and the relationship between the average contact pressure of rough surface and the film thickness ratio was obtained. The relationship between the average contact pressure and leakage rate of three rough surfaces at four operating temperatures was established by mathematical derivation and curve fitting. The results show that the operating temperature has a great influence on the surface quality requirements of the lenticular gasket. When the operating temperature is from 20 t to 100 t, the lenticular gasket with RMS roughness of 0. 4 μm can meet the requirements of the leakage rate index, while when the high temperature oil production operation is from 100 °C to 150 °C, only the RMS roughness of 0. 2 μm can meet the leakage rate index requirements. [ABSTRACT FROM AUTHOR]

Most crocodyliforms of the Bauru Group were found in rocks of the Adamantina Formation, whereas the younger Marília Formation is almost devoid of such fossils. Here, we provide a detailed comparative description of MPMA 02–0005/87, a large skull roof found in Marília Formation deposits of the Monte Alto area, assigning it to a new crocodyliform. Despite its fragmentary nature and puzzling suit of characters, the new taxon possesses enough characters to reject its placement within Notosuchia, which is so far the only crocodyliform clade known from the Bauru Group. We tested its phylogenetic position with twodata matrices, both of which recovered the new taxon within Neosuchia and Eusuchia. Although the material does not preserve any eusuchian synapomorphy, a neosuchian affinity is supported by: anterior extension of the meatal chamber covered by the squamosal; constricted flange of the posterior process of the postorbital; poorly developed posterolateral process of squamosal. Finally, the large size estimated for the specimen, ranging from 2.98 to 5.88 metres, coupled with its possible neosuchian affinity, suggests a possible semiaquatic behaviour, an ecology rarely explored by the predominantly terrestrial crocodyliforms of the Bauru Group. [ABSTRACT FROM AUTHOR]

The flexible high-neck flange is connected to the circular hollow section (CHS) tube through welding, and the placement of the weld seam and corresponding stress concentration factor (SCF) are crucial determinants of the joint's fatigue performance. In this study, three hybrid models combining ant colony optimization (ACO), a genetic algorithm (GA), and grey wolf optimization (GWO) with a random forest (RF) model were developed to predict the stress distribution on the inner and outer walls of the CHS tube under different flange parameter combinations. To achieve this, an automated finite element (FE) analysis program for flexible high-neck flange joints was initially developed based on ABAQUS 2020 software. Parameter combinations were randomly selected within a reasonable range to simulate the nonlinear mechanical behavior of the joint under uniform tension, generating a dataset comprising 5417 sets of data. The accuracy of the FE model was validated through experimental data from the literature. Based on this, feature importance analysis was conducted to reveal the influence of different variable parameters on the stress distribution in the tube of the joint. The flange parameters and tube stress distribution are considered as inputs and outputs, respectively. Three hybrid RF models, specifically ant colony optimization-based random forest (ACO-RF), genetic algorithm-based random forest (GA-RF), and grey wolf optimization-based random forest (GWO-RF), are trained for regression prediction. The results demonstrate that the three hybrid models outperform the original machine learning model in predictive accuracy. The ACO-RF model achieved the highest accuracy with average coefficients of determination ( R m e a n 2 ) of 0.9983 and 0.9865 on the testing and training sets, respectively. Building upon this foundation, the study developed a corresponding open-source graphical user interface (GUI) as a tool for facilitating computations and visualizing results. Finally, a case study on fatigue damage assessment of a flexible high-neck flange joint in a wind-turbine tower is presented to demonstrate the application of the proposed model in this study. [ABSTRACT FROM AUTHOR]

Nitinol, a widely used shape memory alloy in actuator industries, often encounters limitations in joint strength, heat resistance and corrosion resistance when joined to mechanical systems using conventional joining processes such as crimping, screwing or adhesive bonding. To address these challenges, a novel process chain is introduced to produce all-in-one Nitinol micro flanges by laser rod end melting (LREM) in a unique system. A laser beam melts the end of a Nitinol wire into an accumulated spherical liquid, which is subsequently reshaped in a die cavity with different die speeds, die temperatures, and delay time between both steps. Unlike cold forming of solidified preforms, the utilization of a partially solidified melt allows for the fabrication of a flange without cracks and visible oxidation. The resulting flange comprises a partially in the initial shape solidified preform, surrounded by a newly distributed zone. The fabricated flanges show comparable surface quality, size, and microstructure distribution across the range of the studied die speeds and die temperatures. However, achieving the desired flange shape necessitates the selection of an appropriate delay time. This study creates the basis for a process to fabricate Nitinol flanges and examines the influencing factors during the flange processing. [ABSTRACT FROM AUTHOR]

In the traditional pipe curtain construction, two steel plates, known as flange plates, are welded on both sides of the original circular steel pipe, creating a circular steel pipe with flange plates. Adjacent steel pipe with flange plates are welded together to form a new pipe curtain structure. The presentence of the flange plate cause the soil deformation law during jacking process to differ from that of circular steel pipes. In this study, Midas GTS finite element analysis software was used to simulate the jacking process of circular steel pipes with flange plates of different pipe diameters and flange plate positions. The results show that the soil settlement at the pipe top, the soil uplift at the bottom of the pipe, and the vertical displacement of the soil at the flange plate increase continuously with an increase in the spacing between the upper and lower flange plates or an increase in pipe diameter. When the top excavation surface is one section length away from the monitoring section, soil uplift occurs at the monitoring section position. When the top reaches the monitoring section position, the soil deformation becomes settlement. When the top position exceeds one section length of the monitoring section, the soil deformation tends to stablize. Meanwhile, the functional relationship between soil deformation and spacing between upper and lower flange plates, as well as pipe diameter, is obtained by fitting the curve. [ABSTRACT FROM AUTHOR]

The damage caused by small inelastic loadings cannot be neglected when the number of cycles is large. Previous research has mainly focused on the low cycle fatigue (LCF) behaviors of beam-to-column connections, ignoring those of columns. Here, cyclic loading tests were conducted on 22 cold-roll-formed square hollow section columns under multiple small-amplitude loadings. All the specimens failed owing to flange fracture. The effects of the axial force ratio, shear span ratio, and loading amplitude on the LCF behaviors were investigated. Fatigue life prediction methods were developed, and two methods for predicting the lateral resistance deterioration of the specimens were proposed. [ABSTRACT FROM AUTHOR]

Precision metal stamping is an industrial process that uses machines equipped with dies to transform flat sheet metal, either in blank or coil form, into various custom shapes. In addition to stamping, these metal presses can also perform a wide range of processes such as stamping, tooling, notching, bending, punching, flanging, coining and more. Precision metal stamping is widely used for the production of a wide range of products. It can be performed as a single-step operation where each stroke of the metal press produces the desired shape on the plate or in a series of steps. The increasing demand for precision metal parts in various industries from medical to automotive and aerospace has pushed precision metal stamping to the forefront of today's manufacturing. This is because it provides a high degree of design flexibility for defining and implementing tiny features with tight tolerances and unique configurations. [ABSTRACT FROM AUTHOR]

Cold spray additive manufacturing (CSAM) is generally used to repair worn components and build complex on-demand parts by depositing metal powder layer-wise using compressed air. Previous studies on CSAM were focused on printing parameters, materials properties, and printed part mechanical performance. However, the energy consumption and environmental impacts of CSAM processes have not yet been investigated, which are essential factors for sustainable manufacturing. This study aims to investigate the carbon footprint of the CSAM process and compare it with conventional machining processes and other additive manufacturing. The life cycle assessment methodology was followed to calculate the carbon footprint of a pipe flange, considering rod or tube as a feedstock. Results revealed that the machined flange from the tube had the lowest CO2-eq emissions of 31 kg CO2-eq due to low rough machining energy consumption and scrap production, compared to the machined flange from a rod and a printed flange from powder. Moreover, the life cycle carbon emissions increased by 8% and 19% in case of the printed and machined flanges, with uncertainties of 4% and 9%, respectively, when changing feedstock CO2 emissions. From a regional perspective, the CSAM process was responsible for the lowest CO2-eq emissions in Tasmania and South Australia. [ABSTRACT FROM AUTHOR]