Beam System Research Articles

Investigating Stability and Structural Behavior of Steel Pipe Column-Berger Beam Systems

The steel pipe column-Berger beam support system is widely utilized in bridge construction due to its simple structure, convenient installation, high load-bearing capacity, and excellent stability. Stability research on this system is therefore essential. This study employs ANSYS finite element software to conduct a comprehensive analysis, including buckling behavior, node stiffness, and initial defects in the Berger beam support system. The research identifies the first four buckling modes, examines load-displacement curves corresponding to node stiffness values ranging from 0 to 400 kN·m/rad, and evaluates load-displacement curves under varying initial defect ratios. These findings contribute to improving the design and application of the support system. This study not only addresses gaps in current research but also serves as a valuable reference for scholars in related fields. Additionally, it provides practical guidance for engineers involved in bracket design, significantly enhancing their efficiency and effectiveness. In conclusion, the research presented in this paper holds considerable importance for both academic and practical advancements in the field.

The applicability limits of the lowest-order substitute model for a cantilever beam system hard-impacting a moving base.

This paper examines the circumstances under which a one-degree-of-freedom approximate system can be employed to predict the dynamics of a cantilever beam comprising an elastic element with a significant mass and a concentrated mass embedded at its end, impacting a moving rigid base. A reference model of the system was constructed using the finite element method, and an approximate lowest-order model was proposed that could be useful in engineering practice for rapidly ascertaining the dynamics of the system, particularly for predicting both periodic and chaotic motions. The number of finite elements in the reference model was determined based on the calculated values of natural frequencies, which were found to correspond to the values of natural frequencies derived from the application of analytical formulas. The precision of the parameter identification and the outcomes yielded by the substitute model were validated through the calculation of the regions of stable periodic solutions using the analytical Peterka method. Subsequently, the qualitative and quantitative limits of the substitute model's applicability were determined. The quantitative limits were delineated through the utilization of Lyapunov exponents and characteristics associated with the energy dissipation due to impacts and the average number of impacts per excitation period. These characteristics provide a foundation for the introduction of global distance measures of the dynamic behavior of diverse systems within a specified range of the control parameter.

Analyses of the Properties of the NiO-Doped Ga2O3 Wide-Bandgap Semiconductor Thin Films

The study began by pre-sintering Ga2O3 powder at 950 °C for 1 h, followed by the preparation of a mixture of Ga2O3 and 12 at% NiO powders to fabricate a source target material. An electron beam (e-beam) system was then used to deposit NiO-doped Ga2O3 thin films on Si substrates. X-ray diffraction (XRD) analyses revealed that the pre-sintered Ga2O3 at 950 °C exhibited β-phase characteristics, and the deposited NiO-doped Ga2O3 thin films exhibited an amorphous phase. After the deposition of the NiO-doped Ga2O3 thin films, they were divided into two portions. One portion underwent various analyses directly, while the other was annealed at 500 °C in air before being analyzed. Field-emission scanning electron microscopy (FESEM) was utilized to process the surface observation, and the cross-sectional observation was primarily used to measure the thickness of the NiO-doped Ga2O3 thin films. UV-Vis spectroscopy was used to calculate the bandgap by analyzing the transmission spectra, while the Agilent B1500A was employed to measure the I-V characteristics. Hall measurements were also performed to assess the mobility, carrier concentration, and resistivity of both NiO-doped Ga2O3 thin films. The first innovation is that the 500 °C-annealed NiO-doped Ga2O3 thin films exhibited a larger bandgap and better electrical conductivity. The manuscript provides an explanation for the observed increase in the bandgap. Another important innovation is that the 500 °C-annealed NiO-doped Ga2O3 thin films revealed a high-energy bandgap of 4.402 eV. The third innovation is that X-ray photoelectron spectroscopy (XPS) analyses of the Ga2p3/2, Ga2p1/2, Ga3d, Ni2p3/2, and O1s peaks were conducted to further investigate the reasons behind the enhanced electrical conductivity of the 500 °C-annealed NiO-doped Ga2O3 thin films.

The Effect of a Fully Asymmetric Discontinuity in the Elastic Layer of a Geometrically Nonlinear Double-Beam Coupled Mechanical System

This paper presents the effect of an antisymmetric discontinuity in a Winkler nonlinear elastic layer and compares it with the case of a double Timoshenko beam system without discontinuities. The effects of geometric nonlinearity are considered, and the obtained results represent a time-domain analysis. A modified p-version finite element method is applied to analyse the vibrations of mechanical systems with discontinuities. The main contribution of this work is a comparative analysis of a double beam system without discontinuities and a double beam system with an antisymmetric discontinuity in the Winkler elastic layer. The study demonstrates significant deviations in the beam response under a concentrated periodic external force when an antisymmetric discontinuity is present. Its qualitative and quantitative characteristics are illustrated through time histories, showing amplitude variations in the steady-state oscillation regime. Forced vibrations in the time domain are analysed using the Newmark direct integration method. The cases of deviations in the antisymmetric model are explained, highlighting their potential applications in technical practice as well as in the field of deformable bodies and structures.

Search for the Critical Point via Intermittency Analysis in NA61/SHINE

The existence and location of the QCD critical point are objects of both experimental and theoretical studies. The comprehensive data collected by NA61/SHINE during a two-dimensional scan in beam momentum and system size allows for a systematic search for the critical point – a search for a non-monotonic dependence of various correlation and fluctuation observables on collision energy and size of colliding nuclei. Intermittency analysis is a statistical tool used in heavy ion collisions that includes the study of scaled factorial moments (SFMs) of multiplicity distributions in the 2D transverse momentum space to detect power-law fluctuations and explore different aspects of the QCD phase diagram. In particular, proton intermittency has been used to locate the critical point of strongly interacting matter, and, more recently, intermittency of negatively charged hadrons have also been used to study the properties of QCD interactions.

Slope Stability Using Self-Drilling Anchor Rods

Abstract Efficient transport infrastructure is vital for economic competitiveness, yet landslides pose significant threats to roads, endangering safety and infrastructure. This article focuses on the rehabilitation of landslides using self-drilling anchors. Micropiles, which are reinforced drilled piles offer advantages in areas unsuitable for conventional foundation systems due to their adaptability to challenging terrain and minimal vibrations during installation. Our study focuses on a road site in the Bradl belt, characterized by significantly inclined terrain and medium plasticity clay soils. Using numerical modeling through AutoCad and Plaxis 2D, we evaluate the stability of the slope and the effectiveness of the micropile-reinforced concrete beam system. The φ-c reduction method was employed to assess the safety factor, showing that the spatial arrangement of micropiles enhances slope stability significantly. The results highlighted that a spatial orientation of micropiles improves the structural integrity and safely absorbs impacts, outperforming traditional arrangements. This study underscores the potential of micropiles for effectively addressing landslide threats, offering design, safety, and maintenance advantages.

Assessing earthquake resilience in RC buildings: The role of transfer beams and trusses on structural integrity

Buildings equipped with transfer systems, such as transfer beams or transfer trusses, generally possess structural walls, necessitating an assessment of their adequacy in higher earthquake zones. A parametric study is performed on 2D RC frame buildings containing structural walls, (i) utilizing a transfer beam system by altering the position and distribution of the structural walls; and (ii) employing a transfer truss system by altering its positions and increasing the number of bays. The mass participation of buildings using transfer beam systems (∼57 to 69 %) is lower than those of employing transfer truss systems (∼61 to 86 %); it is essential to consider higher mode effects. The deformation behaviour of buildings with transfer systems has transitioned from flexural to shear, or a combination of both, by terminating structural walls or altering the positions of transfer trusses. The shear forces at transfer storeys are markedly increased, leading to considerable stiffness irregularities in elevation. The ratio of the average stiffness of the transfer storeys to the average stiffness of the conventional stories has increased from around 6.9 to 40 due to the inclusion of the transfer truss. The outcome from nonlinear static and dynamic analyses based on the maximum considered earthquake reveal that (i) it is essential to incorporate structural walls throughout the height of buildings; (ii) the presence of transfer beams enhances the vulnerability of the columns above, which leads to major stress concentration at the junctions of transfer beams and structural walls; (iii) the overall enhancement in stiffness is around 75 %, while the reductions in strength and deformability are 28.6 % and 27.5 %, respectively, when transitioning from a transfer beam to a transfer truss system; thereby, buildings using a transfer truss system exhibit reduced energy dissipation capacity, with a reduction in the response reduction factor of ∼ 86.5 %, and (iv) transfer beam systems caused severe damage to beams (exceeding 50 %) and occasionally to columns above or below the transfer storey, complicating retrofitting activities and requiring demolition instead. In turn, it is preferable to entirely avoid buildings with transfer systems in high earthquake zones, regardless of the presence of structural walls.

Inverse-designed metastructures with customizable low dynamic stiffness characteristics for low-frequency vibration isolation

The quasi-zero stiffness (QZS) vibration isolator is considered to be an effective way to address the contradiction between high load-bearing capacity and low-frequency vibration isolation. However, the design of traditional QZS isolators with multiple components, brings about complexity in structure integration, while designing a structure that is compact and lightweight is required for many engineering applications, especially for aerospace engineering. In this study, inverse design was employed to achieve QZS characteristics of the curved beam system. The trajectory of the cross-section center of a curved beam was optimized by using the genetic algorithm. The present design strategy has the advantage of achieving customizable stiffness and load-bearing capability, as well as constructing multiple QZS regions. The harmonic balance method was employed to analyze the dynamic response of the metatructure, and a parameter analysis was conducted to assess its isolation performance. Numerical simulations were also used to validate the theoretical model in the time and frequency domains, respectively. It is demonstrated by experiment that the proposed metastructure can effectively isolate vibrations above 4.67 Hz, with a mass of only 3.2% of the its load-bearing capacity. The presented design strategy provides a feasible solution for the compact and lightweight low-frequency vibration isolators, particularly benefiting miniature devices, precision instruments, and aerospace applications where space and weight constraints are critical.

Experimental Investigation on the Chaos-to-Interwell Motion Transfer in a Bistable Beam-Slider Vibration Energy Harvester

Abstract Bistable structures are widely used for vibration energy harvesting due to their wide bandwidths and extraordinary performance. However, the dynamics of bistable structures are complicated, and inter-well, intra-well, chaotic, superharmonic, and subharmonic vibrations may coexist in some frequency ranges. Inter-well vibration is typically the most desired because of its large oscillation amplitude, which means more kinetic energy can be converted into electricity via different energy transduction mechanisms. In this study, a modified bistable beam-slider vibration energy harvester consisting of a cantilever beam and a movable slider on the beam is investigated experimentally. The slider can move along the beam under the combined effect of the inertial and magnetic forces. Moreover, magnetic nonlinearity is incorporated into the beam to achieve bistability instead of the linear or monostable configurations typically found in existing literature studies. The slider trajectory and the bistable cantilever beam time responses show that the slider can help the bistable beam system transfer from the chaotic to the inter-well vibration orbit. The results show that inter-well vibration can be maintained even with disturbance introduced with 3.92 m/s2 base excitation over the 15 Hz–18 Hz frequency range. The whole transfer process is self-regulating and does not require any external intervention. Therefore, the harvester we designed is self-adaptive, with a substantially broadened operating bandwidth.

An experimental research on the application of retrofitted reinforced-composite beam by polymer-modified mortars to overcome flexural deficient structural systems

This paper presents the results of an experimental evaluation of the retrofitting/strengthening of flexure-deficient reinforced composite (RC) beam systems with polymer-modified mortar (PMM). A total of 12 full-scale beams were tested. The beams were divided into two series, A and B, with six beams each. Each series has three groups of beams depending upon depth. All the beams were subjected to three-point loading under monotonic loading conditions. The beams in series A were loaded until failure, and failure loads were noted. The beams in series B were loaded to 70 % of the corresponding failure load. Afterwards, all 12 beams were retrofitted/strengthened with polymer-modified mortar (PMM) and retested until failure. During loading at the first crack and at failure of the RC beam system retrofitted by the PMM, the crack pattern and deflections were recorded for all the specimens. The results from the experimental tests indicate that the load carrying capacity of the retrofitted/strengthened beam system was significantly greater than that of the control beam for both series. In other words, the load-carrying capacity of the beams in group B was greater than that of the beams in group A and the control beams.

An improved coupled beam method for predicting longitudinal bending behaviour in luxury cruise ships

ABSTRACT This paper describes an improved coupled beam method, designated as MBS-CB, that estimates elastic response in the longitudinal bending of a cruise ship. Initially, the ship structure is discretised into beams, and the coupling relationships between adjacent beams are analysed. Secondly, connector elements with equal stiffness constraints are refined to simulate the coupling behaviour between adjacent beam elements. Meshed beam sections are introduced to simplify the beams involved in total longitudinal bending. A spatial beam system model of the ship structure is established to predict the interaction between adjacent beams and to characterise the longitudinal bending behaviour of the ship. Ultimately, the accuracy of the method is validated through instance analysis. Furthermore, the method is employed to investigate the longitudinal bending characteristics of a large passenger ship, and the participation of different superstructures in the ship's longitudinal bending is obtained through moment distribution coefficients and length proportions.

Stochastic nonlinear model updating in structural dynamics using a novel likelihood function within the Bayesian-MCMC framework

The study presents a novel approach for stochastic nonlinear model updating in structural dynamics, employing a Bayesian framework integrated with Markov Chain Monte Carlo (MCMC) sampling for parameter estimation by using an approximated likelihood function. The proposed methodology is applied to both numerical and experimental cases. The paper commences by introducing Bayesian inference and its constituents: the likelihood function, prior distribution, and posterior distribution. The resonant decay method is employed to extract backbone curves, which capture the non-linear behaviour of the system. A mathematical model based on a single degree of freedom (SDOF) system is formulated, and backbone curves are obtained from time response data. Subsequently, MCMC sampling is employed to estimate the parameters using both numerical and experimental data. The obtained results demonstrate the convergence of the Markov chain, present parameter trace plots, and provide estimates of posterior distributions of updated parameters along with their uncertainties. Experimental validation is performed on a cantilever beam system equipped with permanent magnets and electromagnets. The proposed methodology demonstrates promising results in estimating parameters of stochastic non-linear dynamical systems. Through the use of the proposed likelihood functions using backbone curves, the probability distributions of both linear and non-linear parameters are simultaneously identified. Based on this view, the necessity to segregate stochastic linear and non-linear model updating is eliminated.

A simple but accurate FEM for lateral-torsional buckling loads of mono-symmetric thin-walled beams considering pre-buckling effects

This study intends to present a simple but accurate FE buckling analysis procedure in order to determine lateral-torsional buckling (LTB) loads of mono-symmetric steel beams considering pre-buckling effects. For this, a nonlinear co-rotational FEM for lateral-torsional post-buckling of a thin-walled beam system with non-symmetric cross sections is summarized in which all displacement parameters are defined at centroid. After that, an iterative LTB analysis method is newly proposed with consideration of in-plane deformations due to external loads. Through numerical examples, it is demonstrated that buckling solutions by this method are very well matched with those by lateral post-buckling analysis of the steel beam with lateral imperfections. Finally, numerical results on LTB of simple/cantilever beams under conservative moments, simple beams under gradient moments, simple beams under eccentric compression, a cantilever beam with an un-symmetric channel section, and a cantilever right-angle frame with I-section are presented using conventional LTB, iterative LTB, and post-buckling analysis methods.

Existence and stability of a weakly damped laminated beam with a nonlinear delay

AbstractA weakly damped laminated beam system with nonlinear time delay is studied. The existence and uniqueness are proved by Faedo–Galerkin approach. We prove that the system is stable under some specific conditions on the weight of the delay and the equal wave speeds of propagation. The general energy decay rate is established by using multiplier method and some properties of convex functions. This decay result is obtained without imposing any restrictive growth assumption on the damping term at the origin. In addition, our result improves and develops some existing results in the literature.

Dynamics and Vibrations of Mechanically-Connected Beams System

An analytical methodology of determining the system frequencies of a mechanically-connected beams system and their corresponding mode shapes is proposed. The methodology is demonstrated by analyzing the mechanical system that is consisted of two cantilever beams coupled by a weak beam. The dynamics of the considered system governed by linear partial differential equations of motion were discretized by means of Galerkin’s method into five partial differential equations. Upon applying the mechanical boundary conditions and imposing the continuity constraints which result of twenty boundary conditions, the boundary-value problem (BVP) was significantly reduced to a set of only three linear homogeneous algebraic equations. The latter was only function of three constants and the corresponding system natural frequency. To validate the presented methodology, the analytical results were compared with these obtained numerically using commercial finite element software. Results from the proposed analytical method show an excellent agreement in terms of the mode shapes and natural frequencies with the numerically-predicted results. Furthermore, the effects on the system natural frequencies upon changing the location of coupled weak beam to the two cantilever beam as well as its corresponding length are also investigated.

The vibration responses study of a composite beam system coupled through a nonlinear coupling layer

To explore the potential application of cubic nonlinearity on the vibration control of composite beams, this study builds a model of the composite beam system coupled by a nonlinear coupling layer. The vibration responses of the composite beam system coupled through a nonlinear coupling layer are gained by using the Galerkin truncation method (GTM). On the basis of ensuring the results are correct, the effect of the nonlinear coupling layer and combinations of materials on the vibration responses of the composite beam system is studied and discussed. According to the analysis, vibration responses of the composite beam system coupled through a nonlinear coupling layer can be calculated correctly by the GTM. Complex vibration responses of the composite beam system are motivated by certain parameters of the nonlinear coupling layer. The appearance or disappearance of complex vibration responses is influenced greatly by the change of nonlinear force. Vibration responses of the composite beam system under different combinations of materials have different sensitivities on the nonlinear stiffness of the nonlinear coupling layer. Choosing suitable combinations of materials is also good for vibration control of the composite beam system. The quasi-periodic vibration state can be regarded as a sign of the appearance of targeted energy transfer of the composite beam system. The composite materials have more advantages in the targeted energy transfer of the composite beam system for the structural parameters used in this study.

Dynamic Interaction Analysis of a Coupled System of Permanent Maglev Train and Flexible Track Beam

Vehicle–track beam coupling resonance greatly influences the vibration response of the suspended permanent (SPML) system. Therefore, the study established the coupled dynamic model of the SPML train and the track beam using. The model is used to analyze the dynamic response of SPML trains when passing through the long-span flexible track beam at resonance speed. The accuracy of the model was verified by field tests, which simulated and compared the dynamic responses of maglev train and track beam systems at different running speeds. Furthermore, the coupled vibration response of the train and track beam at resonant speed are investigated to gain insight into the mechanism and vibrational properties of the SPML system in a resonant background. It shows that the dominant frequency of the train, suspension frame, and track beam is 6.74[Formula: see text]Hz. They result in resonance in the SPML system at 30[Formula: see text]km/h. Further analysis shows that adjusting the vertical distance between the mass center of the vehicle and the track beam can effectively alleviate the resonance between the vehicle and the track. Additionally, deformation at the ends of the long-span track beams affects the levitation force and gap of the suspension frame, offering valuable guidance for SPML system design.

Optimizing active chilled beam systems in the South Korean Climate: Comparative analysis of cooling energy and thermal comfort by set-point temperature

In this study, the feasibility of implementing the active chilled beam system (ACBS) in South Korea has been analyzed, and an appropriate control strategy has been proposed. While ACBS is increasingly adopted in North America and Europe, its spread in South Korea has been slow due to different climatic characteristics and a lack of diverse understanding and analysis. Furthermore, research discussing the effects of key system parameters on ACBS is notably scarce. Therefore, this study aims to assess the impact of air handling unit discharge air temperature (AHU DAT) and ACBS entering chilled water temperature (ACBS ECWT) on ACBS and propose a control strategy suitable for the South Korean climate. The applicability of ACBS, compared with existing HVAC systems using this control strategy, has been evaluated. The study incorporates two methodologies: firstly, the impact of control variables has been assessed, and a suitable control strategy has been proposed through a sensitivity analysis of these variables. Secondly, the feasibility of applying ACBS, in comparison with conventional HVAC systems, has been evaluated from the perspectives of energy and thermal comfort. It has been found that system parameters, tailored for the South Korean climate, can maintain a level of thermal comfort like existing HVAC systems while achieving up to 18% in energy savings. Overall, this research not only demonstrates the potential applicability of ACBS in hot and humid climates like South Korea but also emphasizes the need for controlling key system parameters.

Influence of bolt creep induced pre-tightening force relaxation on dynamic response of the bolted joint system

The bolted joint is an important link that affects the accuracy maintenance of the heavy-duty machine tool. Due to bolts of the crossbeam are under a preload of several hundred kN for an extended period, the bolt gradually creeps and elongates as the machine tool's service time increases. This relaxation of the preload results in a degradation of the bolted stiffness, weakening the dynamic response of the bolted joint system. To reveal that the degradation law of crossbeam bolting performance of the heavy-duty machine tool induced by bolt creep, based on the Norton-Bailey(NB) model, a method for analyzing the creep of bolts with precision threads is proposed, and the influence of thread geometry and friction coefficient on the creep stress relaxation of bolts is studied. Considering the interface contact, an interface contact stiffness model is derived based on fractal theory. The dynamic equation of the bolted beam system is established using the Matrix27 stiffness matrix. The dynamic response of the bolted system, resulting from the degradation of interface stiffness due to bolt creep, is analyzed. The results show that the stress relaxation of bolt creep is not only related to creep parameters, but also related to the mate-thread interaction. The dynamic model with Matrix27 stiffness matrix is comparable to experiment in calculation accuracy and efficiency, which provides technical guidance for machine tool dynamics analysis and effectively solves the scientific problem of beam bolting performance degradation during the service of heavy-duty machine tools.

Design, development and test of single beamlet microwave ion source with spot-dense plasma system

In this paper, an efficient ion source with unique characteristics is introduced and proposed. It outlines the generation of a spot-dense plasma just below the plasma electrode aperture of the extractor system through the utilization of a 2.45 GHz microwave plasma source with a power of 1000 W, in the absence of a magnetic field. This source utilizes a 2.45 GHz microwave plasma generator operating at 1000 W, resulting in the generation of a spot-dense plasma just below the plasma electrode aperture of the extractor system, all achieved without the need for a magnetic field.The spot-dense plasma results in the extraction of an ion beam with high current density. Furthermore, the suggested ion source can be utilized in a smaller size using a higher frequency. Therefore, our findings indicate that the proposed method not only substantially enhances the extracted positive ion beam current but also significantly reduces the size of the ion beam source system. Based on the design and simulation results, an experimental model of the ion beam source is constructed. The diagnostic tools provided the beam current density and system efficiency values of 99mA/cm2 and 7×10−6A/W, respectively.