Hollow Beam Research Articles

Investigation on smoothed finite element methods using linear tetrahedral elements for high-speed train hollow axle strength analysis

PurposeThis paper aims to investigate the performance of two novel numerical methods, the face-based smoothed finite element method (FS-FEM) and the edge-based smoothed finite element method (ES-FEM), which employ linear tetrahedral elements, for the purpose of strength assessment of a high-speed train hollow axle.Design/methodology/approachThe calculation of stress for the wheelset, comprising an axle and two wheels, is facilitated through the application of the European axle strength design standard. This standard assists in the implementation of loading and boundary conditions and is exemplified by the typical CRH2 high-speed train wheelset. To evaluate the performance of these two methods, a hollow cylinder cantilever beam is first used as a benchmark to compare the present methods with other existing methods. Then, the strength analysis of a real wheelset model with a hollow axle is performed using different numerical methods.FindingsThe results of deflection and stress show that FS-FEM and ES-FEM offer higher accuracy and better convergence than FEM using linear tetrahedral elements. ES-FEM exhibits a superior performance to that of FS-FEM using linear tetrahedral elements, showing accuracy and convergence close to FEM using hexahedral elements.Originality/valueThis study channels the novel methods (FS-FEM and ES-FEM) in the static stress analysis of a railway wheelset. Based on the careful testing of FS-FEM and ES-FEM, both methods hold promise as more efficient tools for the strength analysis of complex railway structures.

Experimental and numerical investigation of bolted steel endplate with bonded sleeve end connections for pultruded GFRP circular tubular hollow beams

The paper presents an experimental and numerical investigation of bolted steel endplates with bonded sleeve connections developed for connecting pultruded glass fibre-reinforced polymer (GFRP) circular tubular beams. The moment-rotational responses were investigated in detail in terms of initial rotational stiffness, moment capacity, and rotation capacity for all the connections. The effect of endplate thickness and bonded sleeve length was also investigated. Predominant failure modes include bending and yielding of thinner endplates, while thicker endplates with low bonded sleeve lengths exhibit splitting failure in the bonded GFRP beam region. Available design codes for steel joints were used to classify the developed connections in terms of rigidity and strength. The failure modes from the finite element models were well matched by the experimental observations, which include the deformation of the endplate and the cohesive failure within the bonded sleeve region with the GFRP beam.

Temperature Measurement of Trapped, Thermally Sensitive Single Particles in an Optical Trap Using Raman Spectroscopy.

Single particles trapped in an optical trap may experience temperature elevation, yet direct measurement of temperature and its distribution inside the optical trap of several to hundreds of microns in size remains a big challenge. We introduce a method that can measure the temperature inside a universal optical trap (UOT) using Raman spectroscopy of single trapped particles of high thermal conductivity. We measured temperature and temperature distributions inside the UOT using Raman shifts of single-walled carbon nanotubes (SWCNTs) and micron-sized diamonds (MSDs), which are heated by trapping laser beams directly or indirectly, depending on the location of the particle in the trap. We show that the temperature at the center of the UOT is much lower than the temperature along the hollow beams that form a hollow, cage-shaped UOT. In the range of the trapping laser power of 200-2950 mW, the surface temperature of particles trapped at the center of a UOT changes from 322 K to 830 K, correspondingly. This result gives a heating rate as a high thermal-absorbing particle trapped in the center of the UOT with 18.3 ± 0.4 °C/100 mW. In addition, the temperature gradient outside the UOT was also characterized by trapping SWCNT particles outside the UOT. Results show that when a light-absorbing particle is trapped for the study of material property, phase transitions, surface equilibrium process, chemical reactions, etc., this method can be used to measure temperature distribution and its variations in the trap and its surroundings.

Performance of hollow hyperbolic sinusoidal Gaussian beam in weak turbulent optical communication links

The performance of hollow hyperbolic sinusoidal Gaussian beam (HHsGB) propagating in weak turbulent optical communication link is examined by analysing the beam scintillation indices. System parameters’ effect on point-like and aperture-averaged scintillation index values is investigated. The obtained results show that HHsGBs with small source sizes improve the link performance by reducing the scintillation level. In communication systems with a big receiver aperture radius, HHsGBs with high orders significantly minimize the scintillation level. Thus, the provided results will have significant potential in improving free-space optical communication performance in a wide range of applications.

Effectiveness of flange plates on torsional behaviors of ultra-high-performance fiber-reinforced concrete hollow beams

This study investigates the effectiveness of flanges with various types of stirrup and cross-sectional dimensions on the torsional behaviors of ultra-high-performance fiber-reinforced concrete (UHPFRC) hollow beams. A finite element model was developed and validated for simulating the torsional behavior. The impact of the essential parameters of flanges was investigated through experimental and numerical methodologies. The results showed that the inclusion of flanges substantially influenced the torsional strength of UHPFRC hollow beams, attributed to the section torsional plastic resistance moment and UHPFRC tensile capacity in flanges. The effectiveness of flange plates was considerably influenced by the web wall thickness. The stirrup type and the increase in flange reinforcement ratio, flange width, and thickness had a favorable effect on the torsional behaviors of thick-walled UHPFRC beams but minimal effect on thin-walled UHPFRC beams. The failure of thin-walled beams was determined by the web thickness and web reinforcements.

The effects of atmospheric turbulence on the spectral changes of diffracted pulsed hollow higher-order cosh-Gaussian beam

The effects of atmospheric turbulence on the spectral changes of diffracted pulsed hollow higher-order cosh-Gaussian beam

Simulation and Analysis of Three-point Bending Experiment with Hollow Beam Based on Abaqus

Bending resistance is a crucial performance indicator for many hollow beams in service. However, traditional three-point bending experiments face challenges in measuring the stress of the inner wall, making it difficult to study the stress distribution and bending resistance of hollow beams under different external loads. In this study, we established a finite element model based on Abaqus and computed on a server to investigate the stress distribution and bending resistance of hollow beams. Our simulation results show that the structure of the beam meets design requirements, and the hollow beam has a bending resistance of 4.26 kN and a maximum stress of 378.6 MPa when the indenter displacement is 1 mm. As the indenter displacement increases to 10 mm, the bending resistance of the hollow beam increases to 9.04 kN, and the maximum stress reaches 636.4 MPa. We also observed stress concentration on the upper and lower sides of the cross-section, with lower stress in the middle region. Statistical analysis of the stress data revealed that the stress value of the nodes decreased as the distance from the center of the sample increased. Our results demonstrate that modeling and simulation are a feasible approach for studying the bending deformation of hollow beams, and this method provides abundant measurement data without size limitations, making it advantageous over traditional experimental measurement. We recommend that more scholars should explore this approach in their research.

Hollow laser beam induced photoacoustic trapping of micro-sized particles with various sizes

Hollow laser beam induced photoacoustic trapping of micro-sized particles with various sizes

DETERMINING THE OPTIMUM LOCATION OF TWO-FLEXIBLE OUTRIGGER SYSTEMS IN TALL BUILDINGS USING ENERGY METHOD

Construction of tall buildings has been rapidly increasing worldwide, introducing new challenges that demand rigorous engineering. Structural and nonstructural damage to tall buildings can be minimized by implementing appropriate lateral resisting systems, such as the outrigger and belt-truss system. The location of outrigger and belt-truss systems plays a critical role in the behavior, structural integrity, safety, and overall construction cost of tall buildings subjected to lateral loads; thus, they should be selected carefully. This research develops a framework that can determine the optimum location of two flexible outrigger and belt-truss systems in skyscrapers subjected to uniform lateral loading. To achieve this goal, an energy method is applied to maximize the outrigger and belt-truss system’s strain energy. In this approach, the framed tube and effect of outrigger and belt-truss systems on shear core are modeled as a cantilevered hollow section beam with orthotropic plates and rotational springs placed at outrigger and belt-truss location respectively. The optimal location is determined where the rotational spring absorbs the most amount of energy; and this is accomplished by setting the first derivative of the energy equation with respect to the spring’s location, as measured from the structure’s base, to zero. The practical graph developed in this research can aid engineers during the preliminary design of tall buildings for quick calculation of the optimum locations of outrigger and belt-truss systems.

Equation Model for Predicting the Load Capacity of RC Hollow Beams

Equation Model for Predicting the Load Capacity of RC Hollow Beams

Woven Carbon-Fiber-Reinforced Polymer Tubular Mesh Reinforcement of Hollow High-Performance Concrete Beams.

This article presents woven carbon-fiber-reinforced polymer (CFRP) tubular mesh used as a reinforcement on the inner surface of hollow beams made of high-performance concrete (HPC). The tubular mesh was designed to serve as both the tensile and shear reinforcement of hollow beams intended for the construction of small self-supporting structures that could be assembled without mechanization. The reinforcement was prepared with a tri-axial weaving machine from carbon filament yarn and was homogenized using epoxy resin. The interaction of the composite reinforcement with the cementitious matrix was investigated, and the surface of the reinforcement was modified using silica sand and polyvinyl alcohol (PVA) fibers to improve cohesion. The sand coating enhanced bond strength, resulting in the significantly higher flexural strength of the hollow beam of 128%. The PVA fibers had a lower positive effect of 64% on the flexural strength but improved the ductility of the beam. Individual beams were connected by gluing steel parts directly inside the hollow core of the HPC beam. This procedure provides good interaction between the CFRP reinforcement and the glued steel insert and allows for the fast and simple assembly of structures. The weaving of additional layers of the CFRP reinforcement around HPC beams was also explored. A small structure made of the hollow HPC beams with inner composite reinforcement was constructed to demonstrate the possibilities of the presented technology.

Design of a negative curvature hollow-core fiber for transmitting a single-mode dark hollow beam

We propose a nested negative curvature hollow-core fiber that can stably transmit a single-mode (LP11 mode) dark hollow beam with low loss. A pair of resonant tubes is nested inside the cladding tubes in the horizontal direction to enhance the confinement loss of the fundamental mode LP01. Two pairs of glass sheets at different positions within the four cladding tubes in the non-horizontal direction are introduced to suppress the comparatively low loss higher-order modes LP21 and LP02. The numerical simulation results indicate that the loss ratio between the fundamental mode and LP11 mode can reach 28703 when the transmission wavelength is 1.54 µm, and the LP11 mode has the lowest confinement loss of 0.0049 dB/m. Meanwhile, the loss ratios of higher-order modes such as LP21, LP02, and LP31 with the target LP11 mode are above 100. The effective bandwidth of single-mode dark hollow beam transmission can reach 5 nm. This provides an optical fiber solution for single-mode dark hollow beam transmission, which has potential applications in atomic optics, quantum information, and nonlinear optics.

Vibration and Stability Analysis of a Spinning Hollow Functionally Graded Beam with Exponentially Varying Cross-Section

This paper presents an analytical investigation of the whirl characteristics and flexural instability of a spinning functionally graded (FG) hollow beam with exponentially varying cross-section. Applying Rayleigh beam theory, the governing equation of motion of the spinning beam with eccentricity is formulated via the Hamilton principle. The dimensionless whirl frequency equation is obtained for the FG beam with pinned–pinned end supports. On the basis of the obtained model, the whirl frequency, critical spinning speed, and stability conditions of the system are studied. Also, the effects of the main parameters on the whirl characteristics and stability of the system are evaluated. Results show that the unbalanced mass is the main source of system instability. It is also shown that the whirl frequency, critical spinning speed, and stability boundaries of the system are strongly dependent on the slenderness ratio, taper parameter, gradient index, hollow ratio, and eccentricity effects.

Nonlinear generation of hollow beams in tunable plasmonic nanosuspensions

We experimentally demonstrate that a probe beam at one wavelength, although exhibiting a weak nonlinear response on its own, can be modulated and controlled by a pump beam at another wavelength in plasmonic nanosuspensions, leading to ring-shaped pattern generation. In particular, we show that the probe and pump wavelengths can be interchanged, but the hollow beam patterns appear only in the probe beam, thanks to the gold nanosuspensions that exhibit a strong nonlinear response to pump beam illumination at the plasmonic resonant frequencies. Colloidal suspensions consisting of either gold nanospheres or gold nanorods are employed as nonlinear media, which give rise to refractive index changes and cross-phase modulation between the two beams. We perform a series of experiments to examine the dynamics of hollow beam generation at a fixed probe power as the pump power is varied and find that nonlinear beam shaping has a different power threshold in different nanosuspensions. Our results will enhance the understanding of nonlinear light–matter interactions in plasmonic nanosuspensions, which may be useful for applications in controlling light by light and in optical limiting.

Fire resistance of austenitic stainless steel beams with rectangular hollow sections

AbstractThis paper presents a study on the structural behaviour of stainless steel profiles under fire conditions. An experimental campaign of three‐point bending tests on rectangular hollow section beams of the grade 1.4301 (also known as 304) were conducted, considering both steady‐state and transient state conditions. Prior to those tests, the mechanical characterization of the stainless steel was investigated. The constitutive laws obtained by tensile tests at high temperatures are compared with those recommended in Eurocode 3, whose respective material models were recently proposed for modifications, still requiring complete validation. In addition, numerical modelling of the bending tests has been performed afterwards achieving close approximation to the observed experimental results. Finally, analytical methods to predict the load‐deflection behaviour are also presented. Good agreement between the considered methodologies was attained validating their application on the prediction of the fire behaviour of stainless steel beams.

Shear capacity of the Hollow- Reinforced concrete beam with stirrup distance

The ability of reinforced beams to carry loads is determined by two factors, namely the ability to carry bending loads due to moments and the ability to carry shear forces. Previous tests have proven that the flexural capacity of hollow concrete beams is the same as that of normal reinforced concrete beams. This study aims to obtain the effect of shear force on the shear capacity of hollow reinforced concrete beams. In this study used reinforced concrete beams with a cross-section size of 175x350mm with a length of 3000mm. main reinforcement 3D16mm, stirrup reinforcement 8mm, spacing 150mm Material quality f'c = 25 MPa and fy = 400 MPa as control beams. (BN15). Next, blocks are made with the same size and material quality with a stirrup spacing of 10 cm (BN10) then the beams are given cavities using plastic bottles with a length of 3240mm (12 bottles), cavity height: 180mm/3 bottles. 2 hollow concrete beams were made with variations in the spacing of stirrups, namely 150mm (BR15) and 100mm (BR10). The load distribution was regulated by a 2-point load system, namely (a): 50 cm from each position so the value a/d = 1.6, Thus according to the Nawy theory a shear failure will be obtained. The loading is given gradually and gradually increased until failure occurs in the beam. The research aims to obtain the shear capacity of hollow reinforced concrete beams, thus the ability of hollow reinforced concrete beams to carry loads can be relied upon.

Propagation properties of a generalized double-half inverse Gaussian hollow beam with a variable aperture radius

Propagation properties of a generalized double-half inverse Gaussian hollow beam with a variable aperture radius

Study on propagation mechanism and attenuation law of acoustic emission waves for damage of prestressed steel strands

The study of acoustic emission waves propagation mechanism and attenuation laws for damage of prestressed steel strands is the theoretical basis for acoustic emission health monitoring of prestressed steel strands such as stay cables, slings, suspenders, and concrete structures. Firstly, the propagation mechanism of acoustic emission waves in prestressed steel strands is studied using numerical simulation methods. Secondly, the amplitude and energy attenuation laws of acoustic emission waves caused by damage of prestressed steel strands are analyzed by experimental research, and the amplitude and energy attenuation models of the influence of prestress level are constructed. Finally, the constructed acoustic emission attenuation models are analyzed in combination with practical engineering. The results show that numerical simulation visualizes the propagation path of acoustic emission waves in prestressed steel strands; With the increase of prestress levels, the acoustic emission frequency distribution of prestressed steel strands damage ranges from 100 to 200 kHz, with a dominant frequency of 160 kHz, the acoustic emission amplitude and energy attenuation coefficients decrease, and the amplitude attenuation is slower than the energy attenuation; The acoustic emission amplitude attenuation of prestressed steel strands damage in prestressed hollow slab beams is 5 times faster than that of steel strands without surrounding media.

Quantitative analysis of the wave polarization effect on electron capture in a laser acceleration channel

The main purpose of this paper is to explore thoroughly the polarization effect in the capture and acceleration scenario (CAS) scheme using Jones vectors, as well as to conduct a quantitative study of the characteristics of electron beams interacting with EM fields with any polarization states. The simulation provides a circulating hollow electron beam suitable for high-energy particle physics experiments. In this paper, by properly injecting low-energy free electrons into the acceleration channel of a laser pulse in optimal polarization state with an intensity of a0≡eE0/m0cω0=15, a satisfactory result was achieved compared to other works that used extra-high intensity laser pulses (a0≃100). It was observed that the characteristics of the output beam for circular polarization, compared to other polarizations, have more advantages, such as showing less energy spread and spatial divergence, although the mean energy in this case is lower than in other polarizations. Moreover, for a circularly polarized (CP) field, the total fraction of CAS electrons can reach over 98% of the incident electrons. These features demonstrate that the circular polarization in the CAS scheme provides greater acceleration efficiency.

Structural Behavior of Reinforced Concrete Hollow Beams under Partial Uniformly Distributed Load

A Longitudinal opening is used to construct hollow core beam is a cast in site or precast or pre stressed concrete member with continuous voids provided to reduce weight, cost and, as a side benefit, to use for concealed electrical or mechanical runs. Primarily is used as floor beams or roof deck systems. This study investigate the behavior of six beams (solid or with opening) of dimension (length 1000 x height 180 x width120mm) simply support under partial uniformly distributed load, four of these beam contain long opening of varied section (40x40mm) or (80x40mm). The effect of vertical steel reinforcing, opening size and orientations are investigated to evaluate the response of beams. The experimental behavior based on load-deflection measured at central and quarter of tension zones. The experimental test result shows the presence of Hollow decrease the load carrying capacity by about (37.14% to 58.33%) and increased the deflections by about (71.6% for (Hollow ratio 7.4%) to 75.5% for (Hollow ratio 14.8%)) for same applied loadcompared with solid beams with the same properties. The increase shear steel reinforcing will decrease all the deformations at all stages of loading, but particularly after initial cracking and give enhancement in ultimate load capacity of beams by about 31.5% with increasing the amount of shear steel reinforcing by about 50%. Finally, ductility is increased in all cases under partial uniformly distributed load when hollow ratio decreased by about 50% or increased in shear steel reinforcing by about 50%