Vertical Deflection Research Articles

Numerical calculation of the Lorentz force detuning and the pressure sensitivity for the HL-LHC crab cavity

Crab cavities are fundamental components of the HL-LHC upgrade project. These Radio Frequency cavities, operated at the appropriate frequency, ‘tilt’ the proton bunches to increase the luminosity at the collision points IP1 (ATLAS) and IP5 (CMS). Two different superconducting crab cavities were developed: RF Dipole (RFD) for horizontal deflection and Double Quarter Wave (DQW) for vertical deflection. During operation, the cavity walls are deformed due to the loading conditions. This deformation changes the electro-magnetic field inside the cavity and consequently its RF frequency. In the present study, the numerical evaluation of the Lorentz Force Detuning (LFD) and the Pressure Sensitivity (PS) of the DQW cavity, using COMSOL Multiphysics, is presented. The LFD is the fundamental frequency change of the cavity due to the electro-magnetic forces acting on its walls, while the PS is the frequency shift when the cavity is subjected to pressure fluctuations of the helium bath. Finally, a comparison with the results measured during the cold test of the manufactured cavities, and with the previous simulations results obtained for the RFD cavity is done.

Hodnotenie pohodlia jazdy v osobnom vagóne prostredníctvom rovinného dynamického modelu pri zvislom kmitaní

The presented research is focused on a derivation of a mathematical model of a passenger wagon based on a dynamical model in a plane with three degrees of freedom. Vertical oscillation of a passenger wagon is calculated in two different software, namely Matlab and Simpack. It is considered that three degrees of freedom are defined as following: a vertical deflection of a front bogie frame, a vertical deflection of a rear bogie frame (in a running direction) and a vertical deflection of a wagon body. The Lagrange’s equations of the second kind method is used for a derivation of the equations of motion, i.e. for a derivation of a mathematical model of wagon oscillation. Subsequently, the derived equations of motion are solved in the Matlab software as well as in the Simpack software. Both software apply calculation in a time domain. Evaluation of the results is focused on an investigation of ride comfort for passengers. This ride comfort is expressed by the NMV index calculated in five points on a wagon body floor. These calculations come from the formulation defined in the corresponding standard. The results of the NMV indices are presented in the bar graphs based on the numerical values of the NMV indices.

Out-of-plane characteristics of cross-laminated bamboo and timber beams under variable span three-point loading

Given the exceptional mechanical properties of cross-laminated bamboo and timber (CLBT) and its ability to efficiently utilize bamboo and timber resources, CLBT holds considerable potential for applications in modern sustainable timber and bamboo structures. CLBT panels, when used as floors or roofs, typically experience out-of-plane loads. This study investigates the out-of-plane bending and shear characteristics of 5-layer CLBT and cross-laminated timber (CLT) specimens using the variable span three-point loading test method. The results indicated that the developed CLBT exhibited superior mechanical properties compared to CLT, offering a preliminary demonstration of its value in engineering applications. In addition, factors such as the span and outermost lamination influenced the failure modes, vertical deflections, strain distributions, ductility indices, and energy absorption characteristics of CLBT and CLT specimens. This study provides a foundational reference for using CLBT as floor and roof panels subjected to out-of-plane loads and lays the foundation for further research.

Performance evaluation of HY-2 series satellites in marine gravity field recovery

China has successfully launched four Haiyang-2 (HY-2) series altimetry satellites. HY-2A has attracted significant attention in gravity field recovery, but the performance of other HY-2 series satellites, including HY-2B/C/D, is seldom discussed. This study evaluated the performance of all the HY-2 series satellites in recovering marine gravity field. First, the crossover discrepancies in sea surface height of the four satellites, HY-2A, HY-2B, HY-2C, and HY-2D, were analyzed to assess their altimetry stability. It was found that HY-2B had the best altimetry quality, followed by HY-2D. Subsequently, different combinations of altimetry data were used to calculate vertical deflections and gravity anomalies in the South China Sea (112°E−119°E, 12°N-20°N). The results showed that combining data from HY-2B, HY-2C, and HY-2D improved the inversion accuracy of gravity anomalies by 0.3 mGal compared to using HY-2A data alone. HY-2C and HY-2D contributed to enhancing the accuracy of the east component of vertical deflections.

Energy-based efficient residual stress prediction of titanium alloys with lack-of-fusion porosity in powder bed fusion

Residual stress and porosity exert adverse effects on the mechanical properties of metal parts fabricated by powder bed fusion. However, the modeling of the correlation between process parameters, process-induced porosity, and residual stress remains challenging. In this paper, a thermo-mechanical model of titanium alloy with porosity is established, where the relation between process parameters, porosity, and effective material properties is identified. The porosity is first predicted based on the power conservation principle in the process. The effective material properties of as-built titanium alloy with porosity are estimated using a homogenization method. Subsequently, the stress and distortion resulting from temperature variation are predicted using the shear deformation theory. The predicted results exhibit excellent agreement with the predictions and experimental results in the literature. Furthermore, the effect of the main process parameters on the porosity, residual stress, and distortion is investigated. The results show that excessive laser power, small laser radii, and extensive scan tracks contribute to a significant lack-of-fusion porosity. Additionally, the normal stress along the scan direction and vertical deflection are the major residual stress and distortion of titanium alloy with porosity, respectively. The proposed model can serve as a guideline for the design and fabrication of PBF-built titanium alloys.

Inversion method of deflection of the vertical based on SWOT wide-swath altimeter data

The deflection of the vertical (DOV) is the key information in the study of ocean gravity field. However, in most areas, the precision of the prime component of DOV is significantly lower than that of the meridian component. To obtain higher accuracy and resolution of ocean gravity information, researchers have proposed a novel altimeter called the wide-swath altimeter. This altimeter allows for the simultaneous acquisition of high-precision and high-resolution two-dimensional measurements of sea surface height (SSH). In this paper, the Surface Water and Ocean Topography (SWOT) mission with a wide-swath altimeter on board is selected for research. One cycle of SWOT sea surface height data is simulated to inverse the DOV in the Arabian Sea (45°E—80°E, 0°–30°N), and the inversion results are compared with those of conventional altimeter data. The results demonstrate that the difference between the meridian and prime components derived from the inversion of SWOT wide-swath data is minimal, significantly outperforming the inversion results of conventional nadir altimeter data. The advantage of SWOT wide-swath altimeter lies in its ability to use the multi-directional geoid slope at any sea surface measurement point to invert the components in the meridian and prime directions. To investigate the impact of this advantage on inversion precision, this paper employs a method to calculate the gradient of the geoid in multiple directions to invert DOV components. The improvement effect of calculating the gradient of the geoid in multiple directions on the precision of DOV component is analyzed. It is found that the accuracy of DOV inversion has significantly improved with the increase of geodetic gradient calculation direction. In addition, the effects of various errors and grid spacing in SWOT wide sea surface height data on the precision of DOV inversion are also analyzed.

Application and Experimental Validation of Seven-Degree-of-Freedom Beam Element for Girder Bridges during Deck Construction

During bridge deck construction, the deck finishing machine and the fresh concrete often produce large vertical loads and torsional moments acting on the bridge girder system. In some cases, these loads can cause excessive vertical deflection and transverse rotation in the bridge girders, leading to many maintenance and safety problems, such as changes in deck thickness and local and global instabilities during construction. To minimize the potential problems caused by deck construction, the AASHOTO LRFD Bridge Design Specification requires consideration of these torsional moments during the design procedure, and a detailed three-dimensional finite element analysis may be conducted. However, for bridge girders with open-section thin-walled sections, only the solid or shell element can be used to recognize the warping of the girder since the torsional warping effect is not included in the classical beam element. In this research, a warping degree of freedom was added to a beam element, and a three-dimensional beam element with seven degrees of freedom (7-DOF) at each node was derived as an alternative method for analyzing girder bridges during deck construction. A computer program based on the 7-DOF beam element was also developed in MATLAB. To assess the 7-DOF beam element, one bridge was selected to measure the transverse rotation, vertical deflection, and stress of the exterior girder and the first interior girder during deck construction. Also, three full-scale numerical models using solid elements, classical three-dimensional beam elements, and 7-DOF beam elements were created based on the geometries and loads of the experimental bridge. A comparative study was conducted by comparing the results from the numerical models and experimental monitoring data to evaluate the 7-DOF beam element. The results showed that the 7-DOF beam element had excellent behavior in analyzing the girder bridges under construction load, especially in the torsional analysis of bridge girders. Also, unlike the solid element model, which also provided reasonable results, the 7-DOF beam element model can compute the internal forces of the cross-sections along the bridge, which allows the 7-DOF beam element to be an alternative approach for design and research requiring less modeling effort and computational complexity.

Modeling Stiffness and Stress in Serpentine Flexures for Use in a Compliant Bone Plate

Abstract Serpentine flexures offer several advantages for use in linear motion mechanisms, including distributed compliance to reduce stress and increase range of motion. In this work, we develop an analytical model for predicting the moment, vertical deflection, and maximum stress experienced in serpentine flexures in response to an input vertical force. Two classes of serpentines are introduced and modeled with linear motion boundary conditions enforced. Finite element analysis demonstrates a mean model error of 0.86% for these metrics across many flexure topologies. Experimental testing is performed to validate the force–deflection response of three steel serpentine compliant mechanisms. The model is able to predict the experimental stiffness data with a mean error at yield of 5.3%, compared to 6.5% with finite element analysis. Large displacement simulations show the model could remain below 10% error for deflections 3–7 times beyond the mechanisms’ deflection at yield. Finally, the model’s utility is demonstrated in the design of a novel single-piece compliant fracture fixation plate that leverages serpentine flexures to deliver controlled axial motion for long bone secondary healing. Model-derived stress-equivalent flexures are compared in their transverse and torsional rigidity. The proposed model and specific findings can be leveraged to design linear motion mechanisms that incorporate serpentine flexures across a wide range of applications.

Progressive collapse analysis and retrofit of a steel-RC building considering catenary effect

Despite their low probability of occurrence, the consequences of abnormal loads may be very important, both in economic terms and in terms of human lives. This has stimulated the development of strengthening and retrofitting techniques to mitigate the risk of progressive collapse of buildings. However, their application to real-scale buildings is still lacking. This paper describes the progressive collapse analysis and retrofit of a steel-reinforced concrete hospital building. The progressive collapse performance under different column removal scenarios is investigated using both nonlinear static and dynamic analyses. A two-step pushdown analysis procedure is developed to estimate the dynamic amplification factor (DIF) to partially compensate for the dynamic effects. The results have revealed the vulnerability of the building due to the low tensile axial resistance of the beam-to-column connections. Both the hypothesis of DIF = 2 and the almost inversely proportional relationship between DIF and vertical deflection have proven to be ineffective due to the catenary effect. A retrofit solution is proposed based on an outrigger-belt truss system on the rooftop level. The results show the effectiveness of the retrofit strategy. The displacement dynamic response of the retrofitted structure is significantly reduced if compared to the original structure since it goes from about 20 cm to less than 1 cm. However, the tensile strength of column-to-column connections of the top three floors is inadequate and should be increased. To this aim, a strengthening intervention is developed to increase the tensile strength from 565 kN to 965 kN, thus allowing the tensile axial forces caused by the column removed to be resisted.

EWSO: Boosting White Shark Optimizer for solving engineering design and combinatorial problems

Population-based meta-heuristic algorithms are crucial for solving optimization issues. One of these recent algorithms that is now believed to be promising metaheuristic algorithm is the White Shark Optimizer (WSO). Although it has produced a number of encouraging results, it has some certain downsides like other metaheuristic algorithms (MAs). Dropping into the local minimum optima and local solution zones, the uneven distribution of exploration and exploitation abilities, and the slow rate of convergence are some of these downsides. To fight those, two efficient mechanisms, i.e., Enhanced Solution Quality (ESQ) and Orthogonal Learning (OL), have been applied to develop an enhanced version of WSO called EWSO. The effectiveness of EWSO has been comprehensively evaluated using the IEEE CEC’2022 test suite. For further verification and achieving the principle of generality, the proposed algorithm has been used to provide good solutions for three engineering design issues (i.e., Gear train, Vertical deflection of an I beam, and the piston lever), for further applicability it has also been employed to solve two combinatorial optimization problems (i.e., bin packing problem (BPP) and quadratic assignment problems (QAP)). This effectiveness has been evaluated compared to the most recent and common metaheuristics, i.e., Kepler Optimization Algorithm (KOA), Seagull Optimization Algorithm (SOA), Spider Wasp Optimizer (SWO), and some well-known metaheuristic algorithms such as; Sine cosine Algorithm (SCA), Whale Optimization Algorithm (WOA), and Trees Social Relations Optimization (TSR), in addition to the original SWO. The experimental results and statistical measures confirm the effectiveness and reliability of the proposed algorithm (EWSO) in tackling real-world issues. It is able to overcome the previous drawbacks by providing the global optimum and preventing premature convergence through an increase in population diversity.

Experimental studying bending behavior of cold-formed steel-concrete composite beam using perfobond shear connection

An experimental program was carried out on two large-scale steel-concrete composite beams to investigate the effect of the concrete slab dimension on the bending behavior of these beams. The steel-concrete composite beams used cold-formed steel and perfobond shear connectors. The webs of two cold-formed steel and perfobond shear connectors were attached by screws. The parameters evaluated in this program were load capacity, vertical deflection, and the relative slip between the steel beam and the concrete slab. The results showed that the thickness of the concrete slab and the shear connector width enhanced the load capacity and reduced the vertical deflection of steel-concrete composite beams.

Analysis of different combinations of gravity data types in gravimetric geoid determination over Bali

Abstract Following the Regulation of the Head of the Geospatial Information Agency (BIG) No. 13 of 2021, geoid is used as the Vertical Geospatial Reference System in Indonesia. Applications using the geoid as an ideal reference require a much higher accuracy and resolution than the geoid obtained from models derived solely from satellite data. The Indonesian Geospatial Information Agency considers the geoid ideal if it has reached an accuracy of better than 15 cm. Recent studies have combined satellite and other gravimetric data to produce a combined geoid model with increased resolution. Gravimetric data obtained from measurements close to the Earth’s surface, such as airborne and terrestrial gravity data, are particularly attractive because the high-frequency portion of the signal is more apparent and can contribute to the medium to high frequencies of the gravity field. This study models the geoid over Bali Island by combining satellite, airborne and terrestrial gravity data. Calculations were performed using Least Square Collocation (LSC) and Remove-Compute-Restore (RCR) techniques. The gravimetric geoid model was tested against the geometric geoid profile calculated from a GNSS/Levelling survey. The geoid, calculated by combining the GOCO06S satellite gravity model, the GGMplus gravity model and airborne gravity data at an average flight altitude of 4100 m produces a standard deviation of 14.46 cm along the 125 km validation path. After also adding terrestrial gravity data, the standard deviation increased to 16.37 cm. By comparison, the results of the validation of the geoid model from GOCO06S and INAGEOIDV2 with geometric geoids have standard deviation values of 79.56 cm and 16.40 cm, respectively. However, the results of the statistical tests are strongly influenced by the data quality used as validation, in this case, GNSS/Levelling. It is shown that the GNSS/Levelling data over Bali contains significant errors, which have been reduced based on an analysis of geometric vertical deflections. A geometric geoid profile with higher accuracy is required to test the accuracy of the gravimetric geoid models more reliably.

The Dual-Parameter Control of Synchronization in Steel Box Girder Incremental Launching Construction

When a steel box girder is constructed using the jacking method, the contact area between the jack and the bottom of the girder is subjected to complex forces, and it is very critical to ensure the local stability of the girder. When the phenomenon of unsynchronized jacking occurs, it will lead to changes in the contact area and affect the structural safety. In order to solve the above problems, this paper takes the background of the incremental launching construction of the main bridge across the Yellow River on Jiao Ping Expressway, adopts the Midas FEA NX 2021 finite element software to establish a finite element hybrid unit model under the maximum cantilever condition for the first time, and analyzes the local stresses in this state. The results show that the local maximum equivalent stress of the steel box girder is 198.301 MPa, which meets the requirements. The effect of jacking asynchrony on the structural forces is analyzed by simulating jacking asynchrony in the local model. The results show that both vertical jacking asynchrony and lateral deflection will lead to an increase in local stresses in the steel box girder and even steel yielding. On the basis of the above single-parameter study, a two-parameter correlation analysis is carried out to obtain the two-parameter control equation of jacking, the control threshold of the vertical jacking height difference is formulated to be 15 mm, and the dynamic control of lateral deflection is realized according to the control equation. Through comparison, it is found that the two-parameter control threshold of jacking synchronization is reduced, which can supplement the unfavorable state missed during single-parameter control and is a safer and more effective means of control.

A Test of Height Transfer Using Vertical Deflection Measurements by the Digital Zenith Camera VESTA

A Test of Height Transfer Using Vertical Deflection Measurements by the Digital Zenith Camera VESTA

RELATION BETWEEN DOWNWARD AND UPWARD PHASES ON THE TRAMPOLINE BED DURING JUMPING

The time of flight in trampoline competitions relies on the jumping movement executed on the trampoline bed, which can be divided into a downward phase and an upward phase. These two phases of the jumping movement exhibit distinct characteristics. Therefore, the aim of this study was to investigate fundamental data regarding the vertical deflection length, time, velocity, and force involved in the vertical movement on the trampoline bed. The study involved ten trampoline athletes, including participants in the All Japan Championships and members of the Japanese national team. These athletes were instructed to perform 15 consecutive jumps on the trampoline bed, starting from a standing-still position, aiming for maximum height, and maintaining a straight trajectory in the center of the trampoline bed. The findings revealed that all measured parameters were significantly greater in the downward phase compared to the upward phase. Interestingly, it was observed that the jumping height during a prolonged flight is predominantly determined by the actions in the downward phase of the trampoline bed, rather than the upward phase. As a result, the downward phase should be executed as an active jumping movement.

Monitoring displacement, strain, and acceleration of a steel railway bridge

An evaluation of the existing steel railway bridge is necessary to obtain information in supporting policymakers to decide further strategies of the railway bridge maintenance process. The reliability and durability of the existing steel railway bridge were monitored regularly by installing instrumentations on the bridge. The railway bridge characteristics were reviewed by implementing a structural health monitoring system (SHMS). The advantages of the SHMS include an early warning system for the railway bridge structure in order to avoid failures. The objective of this study is to evaluate and monitor conditions of the railway bridge structure. The results of the study explained the vertical deflection of the railway bridge, the stress distribution of the entire truss, and the frequency that happens during loadings. This paper discusses and provides a recommendation to solve problems for users and necessary action in practice. This paper may be used by practicing engineers and researchers.

The Structural Design and Optimization of Top-Stiffened Double-Layer Steel Truss Bridges Based on the Response Surface Method and Particle Swarm Optimization

A lightweight design optimization algorithm is proposed to optimize the design parameters of stiffened double-layer steel girder bridges, the aim of which is to improve structural safety and reduce superstructure works. Taking a top-stiffened double-layer steel truss bridge as the reference project, a multiscale mixed-element model of the initial design parameters is established, and its computational accuracy is verified. Considering the structural configuration and loading characteristics of the bridge, the elastic modulus of steel, the deck plate thickness, the stiffening vertical bar height, and the relative distance between the double-layer main girders are selected as the design parameters for optimization. The mid-span vertical deflection, the axial forces in the stiffeners, the bottom plate of the deck, the compressed web tube at the pier top, and the quantity of superstructure works are chosen as the objective functions to be minimized. A lightweight calculation equation reflecting the relationship between the optimization parameters and the objective functions is established using the response surface method (RSM). Subsequently, an improved weighted particle swarm optimization (WPSO) model is employed to perform the multi-objective optimization of the design parameters for the bridge, and the results are compared with those obtained from the multi-objective genetic algorithm NSGA-II. The results show that the RSM accurately fits the numerical relationship between the optimization parameters and the objective response functions. When minimizing the quantity of superstructure works as the primary control objective and minimizing the mid-span vertical deflection and the axial forces in the compressed web tube at the pier top as secondary control objectives, the optimization results achieved by WPSO outperform those obtained by NSGA-II. The optimized results lead to reductions of 11.09%, 3.92%, 7.56%, 4.45%, and 8.38% in the respective objective function values of the structure. This method has important theoretical significance for the optimization of structural design parameters.

Effect of the vertical wake deflection on the response of a 12MW semisubmersible FWT

The need to understand the interaction of floating wind turbines operating in the marine boundary layer with other surrounding turbines is of increasing importance as wind farms and rotor sizes get larger. For low wind speed conditions, the wake deflects upwards due to the floating wind turbine built-in rotor tilt and the platform pitch angle. Furthermore, based on field data from the North Sea, a convective atmosphere is likely to occur, especially for lower wind speeds. It is therefore key to understand the combined effect of meandering, wake deflection and atmospheric stability for low wind speed conditions on the floating wind turbines in a wind farm.In this work, to account for atmospheric stability, data from large-eddy simulation (LES) for a 7.5m/s wind speed scenario and three atmospheric stability conditions, are used as input to FAST. Farm to study the effect of the wake deflection upwards on a 12 MW semisubmersible placed 8 rotor diameters (D) downwind of a stationary wind turbine. Three built-in shaft tilt angles cases are considered for the fixed upwind turbine: 12°, 6° and no tilt angle. The main effects of the wake deflection are on the power output of the floating wind turbine in the wake, and on the tower top yaw moment. For stable conditions, the mean tower top yaw moment increases by more than three times. The findings of this work contribute to the investigation of the wake deflection as a control strategy to minimize wake losses in floating wind farms.

Validation of an electro-hydraulic press for dynamic measurement of elastic deformations in agricultural tires

Tests with agricultural tires and wheelsets allow for mitigating the machinery traffic limitations to crop productivity, as it shows the tire-surface interaction under different suitability conditions, optimizing farming processes with the use of technology. Thus, this paper aims to develop an electro-hydraulic press for dynamically measuring elastic deformations occurring in agricultural tires. The experiment used a completely randomized design, evaluating two pneumatic wheelsets, bias-ply and radial, and six vertical loads, 4.9033, 9.8066, 14.71, 19.6133, 24.5166, and 29.4199 kN, on the tire, totalizing 12 treatments with five repetitions. The analyzed parameters are contact area, horizontal and vertical deflection. The collected data underwent an analysis of variance F-test and a polynomial regression analysis. The results showed continuous replicability of the data obtained with the electro-hydraulic press. That demonstrates the efficiency of the developed device for evaluating agricultural tires in a controlled environment. The bias-ply tire presented a smaller contact area than the radial with the increase of incident loads, and the 14.71 kN load achieved a higher amplitude, generating a difference of 40 %. The maximum load resulted in 27 % more horizontal deflections for the radial tire. However, the vertical deflection values were 8 % higher with the bias-ply tires.

Preliminary Results of Marine Gravity Recovery by Tiangong-2 Interferometric Imaging Radar Altimeter

This paper presents for the first time the results of marine gravity recovery using the ocean observation data acquired by Tiangong-2 interferometric imaging radar altimeter (TG2 InIRA) which demonstrate not only the balanced accuracies of the north and east components of deflection of the vertical (DOV) as envisaged, but also the improved spatial resolutions of DOV compared with that by conventional altimeters (CAs). Moreover, much higher measurement efficiency owing to the wide-swath capability and the great potential in accuracy improvement of marine gravity field are also demonstrated. TG2 InIRA adopts the interferometry with short baseline and takes small incidence angles, by which wide-swath sea surface height (SSH) can be measured with high accuracy. Gravity recovery experiments in the Western Pacific area are conducted to demonstrate the performance, advantages and capability of TG2 InIRA. SSH data processing algorithms and DOV calculation have been designed by taking the wide-swath feature into account, based on which, the gravity anomalies are then calculated using the inverse Vening Meinesz formula. The derived gravity anomalies are compared with both the published gravity models and the shipborne gravity measurements. The results show that the accuracy of TG2 InIRA is equivalent to, or even a little better than, that of CAs. The fused gravity result using equal TG2 InIRA data and CAs data performs better than those using TG2 InIRA data alone or CAs data alone. Due to the signal bandwidth of TG2 InIRA is only 40 MHz which is much smaller than that of CAs, much higher accuracy can be hopefully achieved for future missions if larger signal bandwidth is used.