Beam Cross Research Articles

THE STUDY OF THE TECHNICAL CONDITION OF GONDOLA CARS

The article presents the results of the analysis of the technical condition of gondola cars owned by the transport operator BGS rail. The composition of the model range of the car fleet was analysed. It is shown that 14 % of gondola cars produced by Uralvagonzavod have an average service life of over thirty years and have exhausted their service life. Gondola cars of models 12-757 and 12-753 of Kryukov Carriage Works have also exhausted their service life. A positive factor is the presence of innovative cars model 12-7023 produced by KVSZ and 12-4106 model produced by PJSC Dneprovagonmash in the car fleet. Their average age is 6.5 years.An analysis of the main causes of failures that caused the car to uncouple from the train along the route was carried out. In the first place are damage to body elements. This is followed by failures of automatic brakes and wheel sets.Among the damage to gondola car bodies, the first place is taken by malfunctions of the locks on the unloading hatch covers, followed by cracks and breaks in the upper and vertical sheets of the frame cross beams. Broken weld seams of braces and broken linings also pose a serious danger.Failures of auto brakes are caused by loosening of air duct pipes, brake equipment and welded shoes. The main causes of damage to wheel pairs are unacceptable wear of the flange. Among axle box assemblies, the vast majority of failures are caused by excessive heating of the bearings.Failures of automatic coupling equipment are most often caused by fractures of the centering beam and breaks (cracks) of the pendulum suspension. Cracks and other malfunctions of the automatic coupling body are also observed.The bogies mostly have broken springs and mismatched sliding clearances. Also, a quarter of the uncoupled bogies have expired service life of their elements. The average recovery time for gondola cars was analyzed. Due to malfunctions of axlebox units, cars are under repair for more than 15 days, due to failures of wheel pairs - 11.55 days. The least time is spent on auto brakes – 4.2 days.An analysis of the damage to the bodies of various gondola cars models showed that gondola cars of models 12-9745 and 12-9790 are in the worst technical condition. The least susceptible to damage are the «innovative» gondola cars of models 12-7023 and 12-4106.

Post-mortem analysis of the deposit layers on the lower divertor after the 2023 high particle fluence campaign of WEST

We analysed deposits collected on the lower divertor of WEST after the first high fluence campaign performed in 2023. Deposits were collected on the high field side (thick deposition area) of 2 ITER-grade plasma facing units (PFUs), located on different toroidal positions. Using focused ion beam cross sectioning, the deposits were found to be very thick (12–55 µm). A significant difference was observed in the toroidal direction with thicker deposits for the PFU located at the maximal heat load in the inner side, showing a deposition pattern due to the toroidal magnetic field modulation. Deposits present a complex layer-by-layer structure with dense layers, some melted parts and porosities within the layers. The deposition is mainly composed of tungsten with oxygen, boron, carbon and traces of nitrogen whose composition vary along the radial direction. We identified W-rich deposits in the high plasma flux area near the inner strike point and deposits rich in O, B, C and N in the low plasma flux area further away from this strike point. W dense layers of about 5 up to 40 µm thick in the thick deposit area near the strike point were attributed to the high fluence campaign. Pure boron layers resulting from wall conditioning and processed by plasma wall interactions were also observed.

Spoke-Type Structures in an Ion Diode with Magnetic Insulation of Electrons

The article presents the results concerning the cross-sectional energy density distribution of a pulsed ion beam for two types of diodes with electron open drift: with external magnetic insulation (250 kV, 80 ns, 0.6 T) and with self-magnetic insulation of electrons (250–300 kV, 120 ns, 0.8 T). Anode plasma is formed using a breakdown along the surface of the anode dielectric coating (single-pulse mode) or explosive electron emission (with double opposite-polarity pulses). It was found that, when the energy density of the ion beam exceeds ≈0.4 J/cm2, periodic spoke-type structures with a step of 3–6 cm in the beam cross section are formed. The processes of formation of such a structure—nonuniform density of anode plasma and self-organization of anode and/or cathode plasma in crossed electric and magnetic fields—are analyzed. It is shown that the formation of local plasma regions in the anode–cathode gap of an ion diode can cause the formation of a periodic structure of the cross-sectional energy density distribution.

Machine tool cross beam design, fabrication, and testing using metal big area additive manufacturing

This paper describes the application of metal Big Area Additive Manufacturing (mBAAM) to the fabrication of a machine tool cross beam. The replacement of a traditional box design weldment with a new design printed by wire arc additive manufacturing using the MedUSA system at Oak Ridge National Laboratory (ORNL) is detailed. This requires a new design strategy based on the unique mBAAM capabilities. The intent of the new design is to reduce mass, while maintaining the dynamic stiffness. To compare the two designs, the natural frequencies and mode shapes are measured using impact testing and predicted using finite element analysis. It is confirmed that the printed structure dynamics agreed with the numerical model predictions, which demonstrates that it is feasible to model a large-scale mBAAM part and understand its behavior prior to printing. Another notable outcome of this study is that the significant residual stress and distortion in the print indicate that knowledge gaps remain for widespread implementation of mBAAM.

Variable angle tow-steered fibres based rotating composite beam with rotary oscillations – Parametric excitation/instability analysis

This study is concerned with the stability analysis for various vibrational motions of tow-steered variable angle fibres based composite rotating beam with time varying speed. The formulation combines a higher order theory introducing sine function along with finite element methodology. It satisfies the plane stress condition in width direction of beam. The displacement kinematics are generic in the sense it includes various possible vibrational motions like chord and flap wise motions, torsional and axial vibration behaviours. The equilibrium equations for the proposed problem evolved adopting virtual dynamic work are then transformed into the equations of Mathieu-Hill type considering time varying harmonic rotational speed. Using Bolotin’s procedure coupled with C1 continuity-based beam element, the parametric resonance zones along with boundary limits are numerically evaluated. The eigenvalue type of solution methodology applied for the detailed study is validated for accuracy and computational efficiency against the time domain dynamic response analysis. Based on in-depth analysis, dynamic instability characteristics in terms of resonance range and origin of instability of composite beam subjected to the chord and flap wise, torsional and axial motions are studied considering curvilinear fibre path angles, beam cross section, hub radius, thickness ratio and mean rotary speed.

A mixed-dimensional formulation for the simulation of slender structures immersed in an incompressible flow

We consider the simulation of slender structures immersed in a three-dimensional (3D) flow. By exploiting the special geometric configuration of the slender structures, this particular problem can be modeled by mixed-dimensional coupled equations. Taking advantage of the slenderness of the structure and thus considering 3D/1D coupled problems raise several challenges and difficulties. From a mathematical point of view, these include defining well-posed trace operators of co-dimension two. On the computational standpoint, the non-standard mathematical formulation makes it difficult to ensure the accuracy of the solutions obtained with the mixed-dimensional discrete formulation as compared to a fully resolved one. Here we proposed to circumvent theses issues by imposing the fluid–structure coupling conditions on the 2D fluid–structure interface but in a reduced way still taking advantage of the 1D dynamic of the slender structure. We consider the Navier–Stokes equations for the fluid and a Timoshenko beam model for the structure. We complement these models with a mixed-dimensional version of the fluid–structure interface conditions, based on the projection of kinematic coupling conditions on a finite-dimensional Fourier space on each beam cross section. Furthermore, we develop a discrete fictitious domain formulation within the framework of the finite element method, establish the energy stability of the scheme, provide extensive numerical evidence of the accuracy of the discrete formulation, notably with respect to a fully resolved (ALE based) model and a standard reduced modeling approach.

Fatigue life prediction of cracked cross beam of mining linear vibrating screen under cyclic load

The cross beam of a mining linear vibrating screen is prone to cracking under long-term cyclic load. In order to accurately predict the fatigue life of the cracked cross beam, a coupled analysis method of vibration and crack propagation is proposed. A 2D dynamic model of the vibrating screen is established based on the finite element method, which is verified by the vibration test platform. The cracked Euler beam element is used to model the cracked cross beam. The effects of crack depth, amplitude of excitation force, frequency of excitation force, and crack location on the crack-tip stress intensity factor of the cracked cross beam are investigated in detail. In addition, an iterative method is proposed on the basis of the Paris model. The residual service life of the beam under different frequencies of excitation force, amplitudes of excitation force, spring stiffness, crack positions, and degrees of stiffness imbalance are discussed. The results demonstrate that the fatigue life of the beam increases as the frequency of excitation force and spring stiffness increase. The increase of the amplitude of excitation force and spring permanent deformation reduces the fatigue life. The conclusion obtained provide some theoretical guidance for the design and routine maintenance of mining linear vibrating screens.

Dynamics of a cross beam with a straight crack in a mining linear vibrating screen

Cross beam fracture is one of the common failures of vibrating screens, and crack is the early manifestation of fracture, which is hard to detect. In order to meet the screening requirement of the vibrating screen and improve the service life of the cracked beam, the cracked Euler-Bernoulli beam model is established to investigate the dynamics of the cross beam with a straight crack under different weights of eccentric block, processing capacities, and Rayleigh damping coefficients based on the finite element method in this paper. The local flexibility coefficients are derived from the principles of fracture mechanics and strain release energy and solved by the adaptive five-point Gaussian Legende algorithm. The stiffness matrix of the cracked beam element is calculated through the inverse method of total flexibility. The four order Runge-Kutta algorithm and MATLAB tools are used to solve the dynamic equation of the cracked cross beam. The relationship between the vibration amplitude of the cracked cross beam and the weight of the eccentric block is studied by fitting formulas using the least squares method. The influence of different weights of eccentric block, processing capacities, and Rayleigh damping coefficients on the vibration amplitude and service life of the cracked beam are discussed. The results show that the greater the weight of the eccentric block, the shorter service life of the beam. When the damping is greater, the service life of the cracked beam is longer.

How numerical simulations helped to achieve breakeven on the NIF

The inertial confinement fusion program relies upon detailed simulations with inertial confinement fusion (ICF) codes to design targets and to interpret the experimental results. These simulations treat as much physics from essential principles as is practical, including laser deposition, cross beam energy transfer, x-ray production and transport, nonlocal thermal equilibrium kinetics, thermal transport, hydrodynamic instabilities, thermonuclear burn, and transport of reaction products. Improvements in radiation hydrodynamic code capabilities and vast increases in computing power have enabled more realistic, accurate 3D simulations that treat all known asymmetry sources. We describe how numerical simulations helped to guide the program, assess the impediments to breakeven, and optimize every aspect of target design. A preshot simulation of the first National Ignition Facility experiment that surpassed breakeven predicted an increased yield that matches the experimental result, within the preshot predicted uncertainty, with a target gain of 1.5. We will cover the key developments in Lawrence Livermore National Laboratory ICF codes that enabled these simulations and give specific examples of how they helped to guide the program.

Two-dimensional space charge limited current in regime between accelerating diode and drift space for sheet and circular beam

We develop a general electrostatic steady-state model to calculate the two-dimensional (2D) space-charge-limited current (SCLC) with an initial velocity v0 (i.e., kinetic energy eKV=mv02/2) injected from a cathode into a vacuum diode with a spacing D and a potential difference of Vg. We consider two types of beam cross section: (a) a sheet beam with a width W and (b) a circular beam with a radius R, where both W and R are larger than D in the calculation. By introducing a parameter ε≡KV/Vg≥0, we can tune the operating regime to be in between the accelerating diode (ε≪1) and drift space (ε≫1). Hence, we verify the 2D SCLC model by converging to some prior analytical findings such as the 2D Child–Langmuir law at ε = 0, 2D SCLC at drift space at ε≫1, and their 1D limits at W/D≫1 or R/D≫1. Our 2D SCLC model indicates that there is a maximal value at ε∼1/60, which is independent of W/D or R/D. Furthermore, the hysteresis behavior is also studied when the injected current density is beyond the SCLC threshold and its dynamics are mainly influenced by ε instead of geometrical effect. This model is useful in high current electron beam emission with a finite emission area and with a non-negligible arbitrary injection kinetic energy.

40‐1: Development of the Auto Monitoring Method of Laser Beam Shape and Size by Employing the AI and Computer Vision Algorithm

The beam shape of the laser cut process to change the display shape is very important in the laser cutting quality, and the laser beam shape was measured by using the beam profiler as a measuring instrument. Since the beam profiler cannot be used due to damage caused by the high laser processing power used in mass production, the beam shape be managed that the sample was created by laser beam cross shot drawing on the material and it was manually measured by using a microscope. However, this method had problems with a long management period (measured once a month), a machine down for the measurement, the measurement deviation between engineers, and inability to manage history, so it was necessary to develop AI‐based shape automatic management technology. To solve this problem, an AI agent program with the AI technology to determine OK, NG of laser beam and the beam size measurement technology based on the image processing was developed and applied to the production line. Through this program, automatic management and history management of beam shape and size that was not possible with previous method have become possible. It was confirmed that the AI and image processing technologies developed through this study can be important technologies that can have a ripple effect on the development of other technologies.

DEFORMATION OF END CROSSBEAMS OF STEEL BRIDGES RELATED TO SUSTAINABILITY OF BRIDGE JOINTS

Both AASHTO and Eurocode stipulate that the deflection of end crossbeams of bridges must be limited to 5 mm under the influence of frequent traffic loads. After a thorough literature review and survey of data from manufacturers of bridge joints, it must be concluded that the background of this requirement is not really based on facts. Durability of bridge joints certainly does not appear to be the basis. Another valid reason can be the comfort of road user, which is effectively disturbed by driving over bumps and thresholds. Although the road user expects light shocks at the end of a bridge, the acceleration inside the vehicle must be limited. Therefore, the state of a wheel driving over a threshold has been studied, by applying analytical equations taken from literature and extended. These allow a fairly accurate simulation of the state. Force required to cross the threshold produces an acceleration of wheel, which is transmitted to vehicle's sprung chassis. In the latter one finds the acceleration to which persons are subjected. Several values of comfort can be considered. It turns out that 5 mm limit is very conservative, and one could easily allow up to double the end cross beam’s deflection.

DEFORMATION OF END CROSSBEAMS OF STEEL BRIDGES RELATED TO SUSTAINABILITY OF BRIDGE JOINTS

Both AASHTO and Eurocode stipulate that the deflection of end crossbeams of bridges must be limited to 5 mm under the influence of frequent traffic loads. After a thorough literature review and survey of data from manufacturers of bridge joints, it must be concluded that the background of this requirement is not really based on facts. Durability of bridge joints certainly does not appear to be the basis. Another valid reason can be the comfort of road user, which is effectively disturbed by driving over bumps and thresholds. Although the road user expects light shocks at the end of a bridge, the acceleration inside the vehicle must be limited. Therefore, the state of a wheel driving over a threshold has been studied, by applying analytical equations taken from literature and extended. These allow a fairly accurate simulation of the state. Force required to cross the threshold produces an acceleration of wheel, which is transmitted to vehicle's sprung chassis. In the latter one finds the acceleration to which persons are subjected. Several values of comfort can be considered. It turns out that 5 mm limit is very conservative, and one could easily allow up to double the end cross beam’s deflection.

A Simple Assessment Method for Mass of Cross Beams of Timber Guardrails

A Simple Assessment Method for Mass of Cross Beams of Timber Guardrails

Broadening of electron cyclotron power deposition and driven current profiles caused by dissipative diffractive propagation

Improvements in electron cyclotron resonance heating (ECRH) and current drive (ECCD) predictions are important issues for the design and control of high-performance fusion plasmas in future devices, where these should play a more important role as actuators than in devices to date. A newly developed EC-prediction package based on the quasioptical ray tracing code PARADE revealed in JT-60SA that (i) the radial profiles of both EC power deposition and driven current are broadened and (ii) the net driven current is increased by a few kA/MW, in comparison with conventional predictions due to dissipative diffractive propagation (DDP). The mechanism of DDP is as follows: EC wave beam obliquely passing through the resonant surface is dissipated non-uniformly on its beam cross section, so that the beam trajectory shifts gradually and thus the resonant position also shifts, resulting in the broadened power deposition profile. This novel ECCD and ECRH prediction package based on PARADE is applicable not only to JT-60SA but other existing devices and even, future devices.

Sequential Computer Simulation of H-minus Ion Dynamics from Source to RFQ Exit with Beam Rotation

An end-to-end simulation of the beam dynamics in the system of extraction, beam transportation and the first section of the accelerator (RFQ) is carried out. The proposed method of modeling the dynamics of ions from the source to the exit from the RFQ made it possible to quickly and efficiently change the parameters of the matching system depending on the final results of the beam passing into the RFQ. A system for matching a beam of negative hydrogen ions has been developed and optimized, which makes it possible to rotate the beam to block the propagation of cesium into the accelerator channel and to match the beam with RFQ. As a result of optimization of the matching channel, it is possible to obtain an emittance increase in RFQ of no more than 25 % for 90 % of the beam fraction, while the capture of beam particles in the acceleration mode is 98 % of the injected beam. The increased drifts in the matching system leave enough space for the placement of diagnostic equipment, a vacuum system and a beam correction system. The dependence of the beam dynamics in the RFQ on the charge distribution over the beam cross section at the output of the matching channel is established.

New insights on bonding mechanism of FCC and BCC high entropy alloy microparticles upon supersonic impact using micromechanical adhesion test

Coating buildup in cold spraying (CS) relies on particle bonding upon impact, thus making it a significant area of study. High entropy alloys (HEAs) are a class of materials with superior work-hardening ability and resistance to softening, making their particle impact and bonding particularly important to understand for their cold sprayability. In this study, the splat adhesion strength is measured with a scratch test for FCC CoCrFeMnNi and BCC AlCrFeMnNi HEA microparticles deposited on mirror-polished SS304 substrates. Nanoindentation tests were conducted to estimate the tensile and shear strengths of the HEA powders. The results showed that particle deformation and jetting were dominant in the FCC HEA/SS304 system, while substrate deformation was dominant in the BCC HEA/SS304 system. Focused ion beam cross sections of particles confirmed that the FCC HEA had good bonding and underwent significant deformation and grain refinement at the substrate/particle interface, while the BCC HEA had limited bonding only in the sheared zone of the particles.In spite of the very limited deformation of BCC splats, their average adhesion strength was measured to be 451 ± 141 MPa, which is significantly higher than that of FCC splats, with an average value of 308.7 ± 69.3 MPa. Fracture surface analysis revealed that FCC splats consistently exhibit ductile fracture, regardless of whether it occurs at the particle, substrate, or interface. In contrast, for BCC splats, fracture was ductile when occurring at the interface and substrate sides, while it was cleavage when occurring on the particle side. These findings suggest that the toughness and shear strength of the bonding developed at the interface were higher than those of the particle. It was found that the flattening ratio (FR) of the particles decreases for both FCC and BCC HEA splats with an increase in particle size, resulting in a decrease in adhesion strength. Metallurgical bonding has been identified as the primary factor contributing to the adhesion strength of both FCC and BCC HEA splats. Particle penetration, indicative of mechanical interlocking, appears to have little or no effect on adhesion strength. However, it does positively influence the increase in adhesion energy of the splats.

Full wave modeling of radio-frequency beams in tokamaks in the electron cyclotron frequency range

Simulation of full wave, without paraxial approximation, high-resolution solution of wave equations in frequency domain in the electron cyclotron resonance (ECR) frequency range for realistic Tokamak plasma parameters became possible by using recently formulated hybrid iterative algorithm [Svidzinski et al., Phys. Plasmas 25, 082509 (2018)] for numerically solving discretized wave equations. This approach combines time evolution and iterative relaxation techniques into iteration cycles. This algorithm is implemented in 2D code FullWave, solving wave equations in Tokamaks in cold and hot plasma models, and it has been tested in 3D full wave iterative RF beams simulation tool, which is presently being developed to model 3D ECRH RF beams in fusion devices using dynamic grid adaptation. The results of 2D full wave modeling, assuming specified toroidal mode number, of ECRH RF beams in DIII-D plasma, performed in the cold and hot plasma models for outboard and top launch scenarios using FullWave are presented. Nonlocal hot plasma response model, based on accurate numerical solution of linearized Vlasov equation, is used to model beam propagation and absorption in the 2nd electron cyclotron harmonic region. Demonstration of capability of the hybrid iterative algorithm to model ECRH RF beams in 3D is made by simulating a substantial part of realistic beam in DIII-D, launched from outboard side of the machine. All relevant physics of RF beam propagation, most of which is not captured in paraxial approximation, such as beam's divergence, interference between the X and O modes in the beam, X-O mode conversion, beam splitting into the X and O mode beams, transformation of beam's cross section, and absorption at the 2nd electron cyclotron harmonic, is captured in the simulations. A numerical technique to find an optimal beam polarization at the launcher to launch a nearly pure X or O mode beam in plasma is developed and tested.

Dispersion scan frequency resolved optical gating for consistency check of pulse retrieval.

Many methods commonly used to characterize ultrafast laser pulses, such as the frequency-resolved optical gating (FROG) or the dispersion scan (d-scan), face problems when they are used on pulses with a spectrum or phase varying within the laser beam cross section or the acquisition time. The presence of such pulse shape variation leads to discrepancy between the measured FROG trace and its reconstructed counterparts. Nevertheless, it is difficult to reliably discern this shape variation because even the distorted experimental FROG trace can be reasonably reproduced by a realistic pulse shape. In this work, we examine and discern the variation of the pulse shape based on a new method, dispersion-scan FROG (D-FROG), which combines the idea of dispersion scanning with the FROG method. This technique provides a means of careful evaluation of the laser pulse based on a set of FROG traces connected by known dispersion changes. Therefore, this method can disclose seemingly correct pulse retrievals from distorted datasets. The D-FROG method can be used as a simple extension of the FROG technique to provide a consistency check able to identify the shortcomings in the pulse characterization.

SiC based beam monitoring system for particle rates from kHz to GHz

The extremely low dark current of silicon carbide (SiC) detectors, even after high-fluence irradiation, was utilized to develop a beam monitoring system for a wide range of particle rates, i.e., from the kHz to the GHz regime. The system is completely built fromoff-the-shelf components and is focused on compactness and simple deployment. Beam tests using a 50 um thick SiC detector reveal, that for low fluences, single particles can be detected and counted. For higher fluences, beam properties were extracted from beam cross sections using a silicon strip detector.Overall, accurateresults were achieved up to a particle rate of 109 particles per second.