Circular Beam Research Articles

Performance of circular concrete-filled steel tube beams under monotonic and cyclic loadings

This study explored the performance of concrete-filled steel tube (CFST) beams under monotonic and cyclic loadings. Experiments were performed on nine simply-supported 140-mm-diameter CFST beams, which were classified into three groups by the diameter-to-thickness (D/t) ratios of 56.0, 46.7, and 40.0, conforming to Eurocode 4. The experimental results indicated that CFST beams exhibited high ductility. The buckling of steel tubes governed the plastic behavior and the ultimate state of CFST beams. The deformation and curvature concentrated in the middle region of the beams, forming a plastic hinge. The yield load, ultimate load, and yield and plastic stiffness slightly increased when D/t decreased from 56.0 to 46.7. However, by further decreasing D/t to 40.0, the ultimate and yield loads were significantly increased by ∼100%, the elastic stiffness by up to 58.2%, and the plastic stiffness by at least 187.5%. With a decrease in D/t ratio, the yield deflections slightly increased, whereas the ultimate deflection significantly decreased by up to 56.3%. The strength degradation was more pronounced for CFST beams with a D/t ratio of 40.0. Decreasing D/t ratio increased the plastic-to-yield stiffness ratios. The absorbed energy increased linearly with the increase in deflection in the plastic range. The cyclic loading effect caused an average degradation of 1.7%/cycle for both loading and unloading stiffness, whereas it marginally impacted on strength degradation. A decoupling concept and simplifications were employed to propose a simple model for rapidly estimating the moment capacity of CFST beams, which can be useful in designing and evaluating CFST beams.

Elucidating the effect of circular and tailing laser beam shapes on keyhole necking and porosity formation during laser beam welding of aluminum 1060 using a multiphysics computational fluid dynamics approach

In the attempt to produce lighter battery packs at a lower cost, replacing common copper parts with aluminum components has been a popular approach in recent years. With regard to joining technologies, there is a growing interest in applying laser beam welding in battery pack manufacturing due to several advantages such as single-sided and noncontact access while maintaining a narrow heat-affected zone. Motivated by the need to control and reduce weld porosity in AA1060 battery busbar welding with the ultimate goal to enhance durability and reduce electrical resistance, this paper has been developed with the aim to studying the effect of laser beam shaping on porosity formation and, hence, generate knowledge about the underlying physics of the welding process itself. First, a multiphysics computational fluid dynamics model has been developed and calibrated to experimental data; then, the model has been deployed to study the effect of both circular and tailing beam shapes on melt pool dynamics and the evolution of porosity due to the instability of the keyhole. The study elucidated the importance of the keyhole’s necking on porosity formation. Findings showed that the tail beam shapes, compared to the circular spot, have a pronounced effect on the reduction of the necking effect of the keyhole—this helps to reduce number of collapsing events of the keyhole itself, thereby leading to the reduction of porosity formation.

Analysis and design of axially loaded ring-beam joints connecting steel tubed-RC column and RC beams

This work proposes a reinforced concrete (RC) ring-beam joint system for connecting circular tubed-reinforced concrete (TRC) columns and RC beams. In the joint zone, a thin-walled core steel tube is embedded to reduce the size of the RC ring beam, which is beneficial to construction convenience and architectural layout. A simplified model is established to allow for both the confinement effect of the core steel tube and the load-carrying capacity contribution of the ring beam. This simplified model enables the analysis of the load-resisting mechanism underlying the proposed joint, along with the derivation of an equation for its axial compression capacity. Furthermore, a high-fidelity finite element model is established and validated through test results. Parameter analysis was then conducted to assess the effects of concrete strength, yield strength of the steel tube, thickness of the steel tube, and height of the core steel tube on both the core steel tube stresses and the axial load-capacity of the joints. Formulas for calculating circumferential stresses and longitudinal stresses of the core steel tube are also proposed. The predictions agree well with the results obtained from test and parameter analysis. Lastly, design recommendations and procedures for the joint are proposed, and a design example is given with three types of joints details. The results demonstrate the advantages of the proposed joint in terms of convenient construction and favorable cost-effectiveness.

Propagation dynamics of the controllable circular Airyprime beam in the Kerr medium.

In this paper, we study the propagation dynamics of the circular Airyprime beam (CAPB) in the Kerr medium for the first time. We investigate the effects of the astigmatism factor, the chirp factor, and vortices on the CAPB propagating in the Kerr medium. At the same time, we are also introducing a special-shaped Airyprime beam (SAPB) during its propagation. The transmission characteristics of the CAPB and the SAPB in the Kerr medium are compared under identical conditions. Our theoretical results provide additional possibilities for CAPB modulation in the Kerr medium, thereby promising wider applicability of CAPB in various research areas.

Deformation-based design of hollow coarse-aggregate ultra-high-performance-concrete beams reinforced with CFRP bars

This study aims to develop a novel type of beams strengthened with carbon fiber-reinforced polymer (CFRP) bars and cast using ultra-high-performance concrete (UHPC) with coarse aggregates (CA-UHPC) to address issues such as poor ductility, extensive cracking, and significant deflection observed in FRP-reinforced concrete (FRP-RC) beams. Six hollow beams were fabricated and tested via a four-point-bending test under cycle loading to study the effects of parameters, including CFRP reinforcement ratios, hollow shapes, and hollow ratio on the deformation performances of the beams. The results show that the deformation of all hollow beams under service loads met the requirements of the GB50610 code for deformation. Increasing hollow ratio had a negative impact on the flexural behaviors of beams, and this effect was more pronounced in beams with higher hollow ratios than in beams with lower hollow ratios. The flexural performances of square hollow beams were better than that of circular hollow beams with the same hollow ratio. Compared to other hollow beams, square hollow beams with a hollow ratio of 44.44% demonstrated superior flexural performance and optimal cost-effectiveness. Ultimately, leveraging the computational framework for steel fiber reinforcement and residual deflection, predictive models for deflection were formulated for CFRP-CA-UHPC beams with various hollow configurations under both static and cyclic loading conditions.

Finite element investigation of circular rubberized CFST beams under Four-Point loading

This paper presents the nonlinear finite element (FE) analysis of circular concrete-filled steel tubes (CFST) with rubberized infill concrete (RuC) under flexure. The FE models were first developed and validated against the existing experimental test results of the CFST beams with normal concrete (NC) and RuC (15% and 30% rubber replacement). Good agreement between the numerical and experimental results was obtained. The validated models were then used to perform parametric studies of forty-five specimens to examine the effect of parameters such as tube diameter, tube thickness, steel yield strength, loading distance, span length, and rubber replacement ratio on the CFST beams under four-point bending. Steel tube properties have a direct influence on the beam moment capacity, whereas loading distance and span length have negligible effects on the ultimate capacity. With 30%RuC, ductility improved significantly, but a lower capacity of up to 14% reduction was found compared to CFST beams with NC. A comparison of the initial flexural stiffness of the numerical results with four design codes showed that AIJ and BS5400 gave more accurate predictions compared to EC4 and AISC.

Acoustic black hole designs for circular beams under axial loading

Acoustic Black Hole (ABH), as a non-reflecting wave effect, has been realised in beams and plates by locally changing their thickness. Geometrical ABH designs stem from their transverse-load bearing properties, assuming isotropic material properties associated with engineering materials (e.g., steels). The underlying physics is to manipulate stiffness locally for a transversely-loaded structure, leading to a change in the elastic wave speed. However, the same ABH would have limitations for axial loading, i.e., slender beams for which longitudinal waves dominate. Here, we present a wave propagation approach using wavefront tracking to identify a potential ABH for axially-loaded circular beams. We study wave propagation in three exponential designs of finite length, monitoring the wave-travel time. Indicative of an effective ABH in finite length sections, the wave-travel time increases compared to the case of a beam without ABH. By employing the wave front tracking method for the design of an ABH with axial loading, it is possible to verify the effectiveness of ABHs. Also, various material models, e.g., orthotropic materials such as wood, and different loading conditions can be considered, which opens a new avenue in applications of ABH phenomena beyond conventional vibro-acoustic control problems.

Laser cladding of stainless-steel ball valves by a high-power diode laser source with a rectangular beam spot

In this paper, the laser cladding of Ni60 + WC powder on the stainless-steel ball valves is investigated to improve the corrosion resistance and the wear resistance of industrial ball valves. A 2-kW high-power diode laser source based on beam multiplexing is used as the processing source to clad the ball valves. To make this diode laser source more reliable for laser cladding, a homogenizing optical system is designed and optimized to transform a circular beam spot output from the optical fiber to a rectangular spot with a flat-top distribution. Employing this diode laser source, the laser cladding of the stainless-steel ball valve is successfully achieved by use of the pre-set powder feeding. The hardness testing experiments are then performed on the ball valves of different diameters, followed by the evaluation of the thickness and hardness of the cladding coating. It is experimentally demonstrated that the microhardness of the ball valves is improved by 2.7 times and the cladding layer has no cracks, which proves the superior performance of the stainless-steel ball valves by use of the proposed method.

Coherence and polarization behaviors of partially coherent circular edge dislocation beam in biological tissue

The effects of the several factors on the changes in spectral degree of polarization P(ρ,-ρ,z) and spectral degree of coherence μ(ρ,-ρ,z), μ(ρ,0,z) for the partially coherent circular edge dislocation beam propagating in biological tissue have been studied. It is shown that both beam wavelength λ and dislocation number n have no effect on the initial values of the three, while the values of field points distance ρx and spatial self-correlation length σyy play a significant role. During the propagation, the curves of P(ρ,-ρ,z), μ(ρ,-ρ,z) and μ(ρ,0,z) with different beam parameters will undergo different fluctuation, eventually the former tends to be a certain value less than its initial one and the latter two tend to zero. The smaller ρx is, the higher the coherence of the beam is. The visible light is more suitable for biological tissue disease diagnosis compared to the far infrared and ultraviolet light. The beam with larger n will possess more richer optical distribution when propagating in biological tissues. The difference value between σyy and σxx will significantly influence the change range of P(ρ,-ρ,z), μ(ρ,-ρ,z) and μ(ρ,0,z).

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.

ALE-ANCF circular cross-section beam element and its application on the dynamic analysis of cable-driven mechanism

ALE-ANCF circular cross-section beam element and its application on the dynamic analysis of cable-driven mechanism

Spatial Variation of the Coefficient of Restitution for Frictionless Impacts on Circular Beams

Abstract The spatial variation of the coefficient of restitution for frictionless impacts along the length of a circular beam is investigated using a continuous impact model. The equations of motion are obtained using the finite element method, and direct time integration is used to simulate the collision on a fast time scale. For collision of a pinned beam with a fixed cylinder, the spatial variation of the coefficient of restitution, impulse magnitude, duration of collision, energetics, and the role of damping are investigated. In the absence of significant external damping, the kinematic and kinetic definitions of the coefficient of restitution provide identical results. Experiments validate the results from simulation which indicate that the coefficient of restitution is sensitive to the location of impact.

The abruptly autofocusing characteristics of the circular Airyprime beam in a chiral medium

In this paper, the abruptly autofocusing characteristics of the circular Airyprime beam (CAPB) propagating in a chiral medium is investigated for the first time. The results show that the CAPB splits into the left-handed circularly polarized (LCP) and the right-handed circularly polarized (RCP) beams with different propagating trajectories in the chiral medium. The focal length Zf, the depth of focal length Zw and the peak intensity of two focal field spots in the chiral medium can be effectively manipulated by the combination of initial beam parameters of CAPB (the primary ring radius r0, the scaling factor w0 and the exponential decay factor a) and the chiral medium parameter h. In addition, the expression of Zf derived from CAB can be well applied to CAPB. The Zf and the Zw of LCP and RCP components of CAPB and CAB are the same, but the autofocusing ability of CAPB is about 7 times of that of CAB under the same condition in the chiral medium, almost the same as that in free space. Due to the abruptly autofocusing ability and the propagation properties in a chiral medium, the CAPB may have potential applications in many fields such as biomedical treatment and optical manipulation.

Impurity-free and high-efficiency modification for 30CrMo steel

It is still difficult to simultaneously achieve surface polishing and purity-free modification of 30CrMo steel by conventional treatment technologies. Herein, the continuous circular scanning electron beam process (CCSEBP), a novel route, for direct surface modification of 30CrMo steel is proposed. The changes regularity in microstructure, surface roughness, microhardness and wear resistance after electron beam treatment was investigated. Results indicated that the modified layer was primarily composed of typical acicular and lath martensite. After polishing, the surface roughness was decreased from 2.2 μm to 0.9 μm and microhardness improved significantly, which is closely associated with martensitic transformation. Moreover, the wear amount of the 30CrMo steel after modification is reduced by 50% compared to the pristine specimen. Following appropriate treatment, 30CrMo steel exhibited an extraordinary combination of hardness and finish. This study shed light on the development of high-efficiency modification for electron beam scanning 30CrMo steel.

Multi-focused electric and magnetic field sourcing from an azimuthally polarized vortex circular hyperbolic umbilic beam.

In this paper, one kind of multi-focusing electric and magnetic field which is sourced from an azimuthally polarized vortex circular hyperbolic umbilic beam (APVCHUB) is presented. After passing through a high NA objective, both the electric and magnetic fields of the APVCHUBs will focus multiple times, and a high-purity longitudinal magnetic field (p q =80%) will be generated. Besides, the mutual induction of the vortex phase and azimuthal polarization changes the electric and magnetic fields' vibration state and intensity distribution, making the longitudinal magnetic field carry an m-order concentric vortex. Our findings suggest that the APVCHUB could have potential applications in magnetic particle manipulation, extremely weak magnetic detection, data storage, semiconductor quantum dot excitation, etc.

Electromechanical response of boron nitride nanosheet reinforced nanocomposite beam: A finite element study

The objective of the present study is to investigate the electromechanical response of a piezoelectric boron nitride nanosheet reinforced nanobeam accounting for the surface and the flexoelectric effects using finite element analysis. The finite element model was developed by using the size-based Euler–Bernoulli beam model, modified piezoelectricity theory, and Galerkin's weighted residual method. The boron nitride nanosheet-reinforced nanobeam was loaded with uniformly distributed load and point-loading conditions. Three common boundary conditions for beams such as clamped-free, simply supported, and clamped-clamped have been considered here. The electromechanical behavior of the boron nitride nanosheet reinforced nanobeam has been studied under the pure surface, pure flexoelectric, as well as combined surface and flexoelectric effects. It is observed that the integrated surface and flexoelectric effects are mainly responsible for enhancing the electromechanical performance of the nanobeam. For the thickness H = 20 nm, the maximum deflection of the nanobeam was reduced by ∼50% when both the flexoelectricity and surface effects are combined together for all the support conditions. Moreover, the circular cross-section beam becomes ∼30% stiffer than the rectangular cross-section beam under the integrated effect of surface and flexoelectricity under all loading conditions. Hence, the highly size-dependent surface and flexoelectricity must be explored in the accurate electromechanical behavior of the nanostructure. Furthermore, beam stiffness is highly influenced by the flexoelectric effect irrespective of the beam boundary conditions whereas the surface effect is largely reliant on the beam boundary conditions. This research work provides a methodology to design efficient boron nitride nanosheet reinforced nanostructures that may potentially be applied in the design and development of several nanoelectromechanical systems such as force and pressure-based nanosensors and actuators.

Evolution and particle trapping dynamics of circular Pearcey-Airy Gaussian vortex beams in tightly focused systems.

This study investigates the propagation and evolution of self-focusing circular Pearcey-Airy Gaussian vortex beams (CPAGVB) through high numerical aperture objective lenses. CPAGVB demonstrates a unique light field distribution compared to the circular Pearcey vortex beam and circular Airy Gaussian vortex beam. By adjusting optical distribution factors, main radii, and off-axis vortex pair positions, a variety of light field structures can be generated, including asymmetric micro-optical bottles, quasi-flat-top beam micro-optical bottles, and dual optical bottles. The particle trapping performance of CPAGVB is examined, revealing a gradient force eight orders of magnitude larger than its scattering force, up to twice the peak gradient force, and 2.5 times the scattering force of CAGVB. Further analysis of lateral power flow density, spin density vector, and total angular momentum distribution at the focal plane unveils the dynamics of particle motion toward the center. The Gouy phase difference under varying main radii reveals two types of normalized spin density vectors, characterized by helical and oscillating distributions. Additionally, the study examines the two-dimensional polarization ellipse distribution at the focal plane, elucidating the formation of central polarization singularities with axial vortices and the impact of peripheral polarization rearrangement on phase singularities. This research advances the comprehension of CPAGVB's distinctive properties and potential applications in micro-optical systems and particle manipulation.

Manipulating self-focusing beams induced by high-dimensional parabolic umbilic beams

The excellent property that the intensity of autofocusing beams in the focal plane increases exponentially, makes them especially beneficial for biomedical treatment. We experimentally generate tunable (2+1)-dimensional circular parabolic umbilic beams (CPUBs) for the first time based on the high-dimensional diffraction catastrophe integral, which is determined by the potential function. Such CPUBs have circular and symmetrical intensity distributions in space through radial symmetry transformation. Due to the flexibility of high dimensionality, these light beams have rich light field structures and self-focusing property. Where, the maximum intensity suddenly increases by orders of magnitude in the focal plane. Unlike the classical circular Airy beams, CPUBs exhibit multiple self-focusing points along the optical axis and a needle-like structure during propagation, which can be affected by manipulating the control parameters. The rich properties provide a new perspective for exploring the novel physical mechanisms and phenomena in autofocusing beams. The experimental results verify the correctness of the numerical simulations. CPUBs greatly enrich the autofocusing beam family and will be advantageous for medical treatments, optical micromanipulation, and microscopic imaging.

Abnormally autofocusing vortex Swallowtail Gaussian vector beam with low spatial coherence

The precondition for the application of light beams is the ability to devise light distribution with high precision. Controlling more dimensions for structured light fields is an effective method to improve the ability to devise light distribution. The Swallowtail beam, due to its rich regulatory parameters, provides the possibility to design a light field with a specific intensity distribution. Utilizing the Swallowtail beam as a foundation, we design its initial phase, polarization, and coherent structure, and propose a partially coherent azimuthally polarized circular vortex Swallowtail Gaussian beam (PCAPCVSGB) in our paper. This beam exhibits an abnormal self-focusing ability and forms an easily adjustable optical potential well at the focal plane, providing another effective tool for achieving optical manipulation. In addition, the PCAPCVSGB also shows an interesting vector property. It possesses a stable polarization singularity even with changes in coherence and topological charges, which exhibits a potential application value in optical communication.

Additive Manufacturing of Body-Centered Cubic Metamaterials with Novel I-Shaped Beam Lattice Towards Enhanced Mechanical Properties

The recent advancement of additive manufacturing paves the way to achieve the highly complex design of metamaterials. Mechanical metamaterials are promising materials for high-yield industrial applications since they demonstrate superior mechanical behaviors that cannot be found in natural materials. Designing metamaterials is crucial to ensure enhanced mechanical performances. The objective of this research is to explore different metamaterial lattices utilizing a numerical approach in order to obtain higher mechanical strength. This research employs a Mechanics of Structure Genome (MSG) method to design a novel I-shaped beam with reinforcement lattice metamaterials to attain higher mechanical properties. Three cross-sectional shapes including circular, Ibeam, and Ibeam with reinforcement and their corresponding Body-Centered Cubic (BCC) metamaterials, have been designed applying the MSG modeling approach. The Stereolithography (SLA) based additive manufacturing process is leveraged to fabricate the designed metamaterials. A standard compressive test is performed to characterize the mechanical properties. The test results reveal a remarkable improvement in the mechanical behaviors of the proposed I-shaped beam with reinforcement (Reinf Ibeam). The Reinf Ibeam demonstrates higher energy absorption capacity, stiffness, and strength compared to the other two metamaterials. A 40.57% increased energy absorption/weight ratio, 140% higher stiffness/weight ratio, and 74% larger yield strength/weight ratio are obtained for the Reinf Ibeam in comparison with circular beam lattice metamaterial.