Vibration Characteristics Of Structure Research Articles

Dynamic Response Study of Overhead Contact System Portal Structure Based on Vehicle–Track–Bridge Coupled Vibration

In light of the rapid development of electrified railways, the safety and stability of train operations, as well as the catenary’s interaction with current quality, have garnered widespread attention. Electrified train operation with additional track irregularities serves as a principal excitation source within the vehicle–bridge–catenary system, significantly influencing the vibration characteristics of the system. Addressing the aforementioned issues, we first established the vehicle–track dynamics model and the bridge–catenary finite element model based on the principles of coupled dynamics of the vehicle–track system. These models are interconnected using dynamic forces between the wheel and rail. Subsequently, within the vehicle–track coupled system, track random irregularities are introduced as input excitations for the coupled model, and the dynamic response of the system is simulated and solved. Then, the obtained wheel–rail forces are applied to the bridge–catenary coupled system finite element model in the form of time-varying moving load forces. Finally, the dynamic response characteristics of the catenary portal structure under different conditions are determined. Meanwhile, a study on the vibration characteristics of the truss-type pillar portal structure was conducted, and the results were compared with those of existing models. The results indicate that the vertical and lateral forces between the vehicle and track are positively correlated with the speed and irregularity amplitude. Response values such as the derailment coefficient and wheel load reduction rate are within the specified range of relevant standards. The low-order natural resonant frequency of the truss-type pillar structure has, on average, increased by 0.86 compared to the existing pillar structure, which signifies improved stability. Furthermore, under various conditions, the average reductions in maximum displacement and stress response of this pillar structure are 13.2% and 14.19%, respectively, in comparison to the existing pillar structure, rendering it more suitable for practical engineering applications.

Free vibration analysis of laminated anisotropic doubly-curved shell structures reinforced with three-phase polymer/CNT/fiber material

The present work investigates the vibrational response of laminated anisotropic doubly-curved shell structures reinforced with Carbon Nanotubes (CNTs) short fibers. The fundamental equations are derived from a curvilinear reference system of principal coordinates, employing the Equivalent Single Layer (ESL) methodology. Furthermore, a general variation in laminate thickness is considered. The unknown field variable is described using higher order theories through the unified formulation, taking into account a general interpolation of the unknown variables with Lagrange polynomials across the physical domain. The Hamiltonian Principle is adopted for the derivation of the dynamic equilibrium equations, which arediscretized numerically by using the Generalized Differential Quadrature (GDQ) method. In addition, an efficient isogeometric NURBS-based mapping is adopted for the distortion of the physical domain. The boundary conditions of the differential problem are modelled through a general distribution of linear elastic springs along the lateral surfaces of the three-dimensional doubly-curved solid. The theory is then applied to study the vibrational modes of structures with different curvatures and lamination schemes, taking into account a general distribution of CNTs along the thickness direction. The homogenized properties of CNTs layers are obtained from the Mori-Tanaka procedure, which accounts for the agglomeration effects of the dispersed nanofibers within the matrix. Unlike previous studies focusing on doubly-curved shells reinforced with composite materials and CNTs, the present formulation enables to derive the vibration characteristics of structures made of generally anisotropic materials with general orientations. Furthermore, the calibration of the parameters for the linear elastic springs’ distribution leads to general external constraints within a single element, thus reducing the computational cost of the problem.

Comparative analysis of track damping effect of structure jointly constructed by subway tunnels and high-rise buildings

The joint construction of subways and other public buildings is a relatively newer type of construction. There is little research experience in the vibration characteristics and track damping design for this type of structure. In this study, a field test was adopted to conduct site measurement analysis on the vibration response of the joint construction project consisting of a subway tunnel and a building with typical frame structures. Numerical simulation methods were also adopted to, respectively, assume the use of ordinary tracks and steel-spring floating slab tracks for the subway for the situation where the Cologne-egg high-elastic fasteners were used on the track for damping purposes. Comparisons were performed to analyze the difference in the system vibration response between three different types of track. The results showed that the high-elastic fastener track and floating slab track both have a certain degree of damping effect compared with an ordinary track. Specifically speaking, the former has a damping advantage for frequency bands below 20 Hz, while the latter has the advantage for frequency bands above 20 Hz under the impact of the structural vibration characteristics for this joint construction. For this jointly construction structure, affected by the natural vibration characteristics of the structure, the natural frequency of the floating slab track is within 4 ∼ 10 Hz, and the similar vibration reduction effect can be achieved. This indicates that the structural vibration characteristic of the jointly constructed structure is an important factor determining the appropriate natural frequency of the floating slab track.

Vibration Characteristic Research of 100 m New Polar Exploration Cruise Based on Finite Element Modeling

Luxury cruise ships are high-end passenger ships with facilities on board for the leisure and entertainment of passengers, so the comfort of luxury cruise ships is a matter of great concern. In this paper, a finite element model of a new polar exploration cruise ship is established, and the wet modes of the whole ship are calculated using the virtual mass method and compared with the principal frequencies of the excitation forces to initially verify the rationality of the design of the structural vibration characteristics of the whole ship. The admittance matrix of the vibration velocity to excitation force was calculated by a frequency response analysis, and the vibration velocities at the stern plate and main engine foundations were tested during sailing. Then, the obtained propeller and main engine excitation forces were loaded into the finite element model; the vibration velocities of each compartment were calculated and compared with the compartment vibration velocity test values. The errors were within the engineering allowable range, verifying the accuracy of the excitation forces. The propeller and main engine excitation forces were loaded separately on the finite element model to calculate the vibration velocity of each cabin, and the contribution of the two excitation sources to the vibration velocity of each cabin was analyzed. It was found that the contribution of the excitation source to the cabin response was related to the relative position between the cabin and the excitation source. When the cabin was located in the cabin adjacent to or directly above a certain excitation source, the contribution of the excitation source to the cabin response was greater. When the cabin was farther away from both excitation sources, the contribution of the propeller excitation was greater. This provides a targeted reference for the preliminary vibration assessment and later vibration control of the new polar expedition cruise ship.

Uncertain stochastic vibration characteristic analysis of composite laminated rectangular plate based on improved kriging model

The stochastic vibration analysis of composite laminated structures has been conducted extensively in the field of structural dynamics. Existing studies in this field are primarily conducted based on deterministic structural parameters, whereas the effects of parametric uncertainties on the stochastic vibration characteristics of composite laminated structures are disregarded. This study investigates a composite laminated rectangular plate by considering the effect of interval uncertainty in the intrinsic parameters and load on its stochastic vibration characteristics. A rapid analysis model for the structural stochastic vibration characteristics is established based on an improved kriging model. Additionally, an innovative approach that combines the improved kriging model with intelligent optimization is proposed to solve problems pertaining to uncertainty-propagation analysis of structures. Based on this method, an uncertainty-propagation analysis of structural stochastic vibration responses is efficiently implemented. The effectiveness of the proposed method is demonstrated by comparing the results with those obtained from Monte Carlo simulation. The numerical results indicate that different uncertain factors exert varying degrees of effect on the stochastic vibration characteristics of the plate. Finally, the effects of density, elastic modulus ratio, fiber orientation and load on the interval fluctuation patterns of uncertain responses are discussed.

A method for predicting vibration characteristics of track structure based on rail acceleration and deep learning

ABSTRACT The dynamic test on track structure plays a crucial role in evaluating the operational state. Nonetheless, existing testing approaches involve numerous sensors, resulting in high costs and time consumption. This study proposes an economical, high-precision, and swift solution to predict vibration responses and displacement variations in track structures using rail acceleration. Taking the ordinary track structure and the damping track structure as examples, based on the high correlation between the vibration responses of the rail, track slab and tunnel wall, combined with the proposed Bayesian optimized temporal convolutional neural network model (BOA-TCN), and taking the rail acceleration envelope and vibration level as input, the vibration of tunnel wall and the displacement of rail and track slab are estimated. The results demonstrate that the BOA-TCN model effectively solves the limitation of traditional neural network in accurately capturing vibration characteristics in the frequency range of 1 ~ 100 Hz. The absolute error of the total vibration level prediction is significantly reduced, only 0.74 dB. The single point prediction accuracy of track structure displacement is increased by 80%, the absolute error is 50% of the traditional model, and R2 can be increased to more than 90%.

Surface crack effect on frequency and vibration mode switching of solar-powered aerospace structures

In the engineering design of modern wing panels and their optimal control system, the first step is to find and predict their dynamic characteristics. These characteristics are dependent on material properties, panel geometry, and boundary conditions. In addition, possible fracture existence, imperfections and environmental conditions may unpredictably change the frequency and modes shape of the panel and then the parameters of a control system. In the present paper, the effect of surface fracture depth and orientation on frequency and vibration mode switching of perovskite solar cells-based aircraft wing panels is investigated for the first time. The PSC (perovskite solar cell) panel is made of a polymer substrate reinforced with even-distributed graphene platelets (GPLs) and thin solar layers to enhance the overall electromechanical performance of the whole structure. Equations of motion of the panel are obtained by the Hamilton approach based on the properties of Reddy's third-order shear deformation theory and linear components of the Green-Lagrange strain tensor. The novel aspect is a line-spring model of surface crack by Cartmell et al. adapted to the model of the PSC panel under consideration. The discretization of the established equations of motion for the cracked panel is carried out by the element-free IMLS-Ritz method with mesh-free features. Validation of the obtained solutions is carried out by comparisons with results from previous studies for cracked laminated plates.First, material and geometric properties effect on vibration characteristics of the PSC structure was investigated. Next, partial surface crack depth and orientation angle are examined to show changes in frequency and vibration modes shape of the panel. It is shown, that there is a mode swapping between the second and third modes when transitioning from an intact panel to a cracked one. As the crack length increases, higher-order mode variations become more noticeable, potentially leading to their swapping or the excitation of new ones. Additionally, the findings demonstrate that the surface crack orientation angle significantly impacts the higher-order modes of the panel. When the orientation angle is 90°, the first six modes align with those of the intact plate. Mode shapes and frequency shifts are significant for crack orientation angles between 0° and 90°.

Modeling and free vibration analysis of bolted composite flanged cylindrical-cylindrical shells under partial bolt loosening conditions

The bolted composite coupled cylindrical shell is a common substructure in modern engineering, which may encounter the issue of local loosening conditions during service. Meanwhile, the influence of flanges on the structural vibration characteristics is often overlooked in dynamic numerical analysis. In this paper, a semi-analytical dynamic model for the bolted composite flanged cylindrical-cylindrical shell structure under arbitrary connection conditions is established, and the free vibration characteristics of locally loose structures are emphatically studied. In the model, the annular plate modeling method is developed to achieve the simulation of the flange part. To fully reflect the connection characteristics of the bolted joint, a spring surface model and the corresponding parameter determination method based on fractal contact theory are developed. The equations of motion of the structure are obtained utilizing the Lagrange equations. The accuracy of the model and its predictive ability for the vibration characteristics of the bolted composite flanged cylindrical-cylindrical shell under local loosening conditions are fully demonstrated through numerous comparisons with experimental results from other literature and modal test results obtained under various working conditions. Furthermore, the influence of the number and degree of loosening bolts on the free vibration characteristics of the structure and the coupling phenomenon between different modes are discussed. The research in this paper is expected to provide references for the design of bolted composite flanged cylindrical shell structures and the monitoring of bolt connection defects.

ANALYSIS OF THE CHARACTERISTICS AND CAPABILITIES OF MODERN VIBRATION AND STRAIN GAUGES OF MODERN MEASURING EQUIPMENT

The article analyses the characteristics and capabilities of modern vibration and strain gauges, as well as the existing requirements for vibration measurement devices for wheeled armoured vehicles. The main physical parameters for assessing the strength and vibration characteristics of wheeled armoured vehicles to be measured are determined. Modern accelerometers for measuring vibration have better universal characteristics compared to other types of sensors, as well as a wide frequency and dynamic linearity range. The use of piezoelectric, strain gauge, magnetic induction and laser measuring equipment will allow to obtain physical values of vibration parameters and the stress-strain state of wheeled armoured vehicles and, using data acquisition systems and software, to analyse deviations of limit values in the design and components of the vehicle.
 Improvement of the methodological apparatus for experimental studies of strength and vibration characteristics during testing of wheeled armoured vehicles will improve the quality and simplify the measurement process, which in turn will significantly reduce the time for testing prototypes and ensure timely delivery of weapons and military equipment (components) to the Armed Forces of Ukraine. The use of modern vibration and strain gauges to assess the strength and vibration characteristics of structures and their components will simplify and automate the measurement process, minimising possible errors during testing of armoured vehicles. The results of the work can be used for a rational and justified selection of vibration and strain gauges for testing wheeled armoured vehicles.

Analysis of structural vibration characteristics of embankment dam based on DVMD–VDR

Analysis of structural vibration characteristics of embankment dam based on DVMD–VDR

Metro Monolithic Track Bed Vibration Characterization

With the rapid development of cities, metro transportation has also developed rapidly to solve the congestion problems caused by urban development. However, with the continuous development of metro transportation, the vibration problems caused by it have become increasingly obvious. Based on the phonon crystal theory, this paper investigates the vibration characteristics of the metro track structure. It analyzes the influence of the track structure parameters on the band gap characteristics to regulate the metro vibration band gap range. To study the band gap characteristics of metro monolithic bed track structure, establish the double-layer Euler beam model and use the plane wave expansion method (PWE) to calculate its energy band structure; use the finite element method (FEM) to calculate to get its band structure, frequency response function, and time domain analysis. The calculation of PWE shows that there is a band gap in the range of 0–300[Formula: see text]Hz for the metro monolithic track bed, which is 0–194.5[Formula: see text]Hz; the calculation of FEM shows that the range of band gap is 0–193.7[Formula: see text]Hz. Fastening spacing, stiffness, and sub-slab support stiffness will have an impact on the band gap, so appropriate fastening and spacing need to be selected for effective vibration damping of the track structure. The results show that the band gap characteristics of the metro monolithic track bed can be calculated effectively and accurately by using the phononic crystal theory.

Exploring the vibration and energy absorption characteristic of auxetic tubular structure: an experimental analysis

This experimental study delves into the vibration response and energy absorption characteristics of three distinct auxetic tubular structures under quasi-static compression: the Reentrant, Double-V, and Anti-Trichiral designs. Notably characterized by their negative Poisson’s ratio, these structures exhibit superior mechanical properties in comparison to conventional tubular structures with a positive Poisson’s ratio. For consistency, all samples were standardized in terms of diameter and height, while variations due to unit cell geometry were parameterized based on the structure’s weight. The samples were fabricated using Fused Deposition Modeling (FDM) with both PLA and PLA-Carbon filaments. Modal testing was conducted to evaluate structural damping, providing insights through time domain plots and frequency response functions. Subsequent compression testing facilitated the assessment of force-displacement relationships, thereby enabling the quantification of energy absorbed, specific energy absorption, and peak crushing force metrics. The analysis revealed that Reentrant unit cells constructed from PLA exhibited a 5% higher damping efficiency compared to Double-V and 4% higher than Anti-Trichiral units. Similarly, Reentrant units in PLA-Carbon demonstrated an 8 and 30% increase in damping relative to Double-V and Anti-Trichiral, respectively. During quasi-static compression, Double-V units in PLA showcased a 66 and 13% superior energy absorption capacity over Reentrant and Anti-Trichiral units, respectively. With PLA-Carbon, Double-V units exhibited a 28 and 116% enhanced energy absorption capacity compared to Reentrant and Anti-Trichiral units, respectively. This comprehensive evaluation offers insightful revelations into the damping and energy absorption capabilities of varying auxetic cell structures when composed of different materials, highlighting their potential in engineering applications.

Nonlinear vibrations analysis of two-directional functionally graded porous cylindrical shells resting on elastic substrates in a thermal environment based on Donnell nonlinear shell theory

The primary objective of this study is to investigate the nonlinear free vibrational characteristics of temperature-dependent two-directional functionally graded porous (TDFGP) cylindrical shells resting on elastic substrates in a thermal environment. To accomplish this, the thermomechanical equations are derived based on the Donnell nonlinear shell theory framework in conjunction with the von Kármán assumption. Two-directional functionally graded porous cylindrical shell models have mechanical properties that can change smoothly and continuously across the length and thickness of the shell. Additionally, it is assumed that the internal porosities in the matrix materials can be dispersed into two independent patterns, either even or uneven porosity distribution. The nonlinearity in free vibration assessed via the nonlinear-to-linear frequency ratio concerning the central deflection amplitude can be gained employing the Galerkin discretization approach and modified Poincare–Lindstedt (P-L) method. The accuracy and effectiveness of the present analytical model are indicated through comparison with existing solutions. Finally, some comprehensive parametric investigations are carried out to gain insight into the impacts of several factors on the nonlinear free vibration characteristics of structures under different conditions. The results of this article demonstrate that parameters such as gradient indices, volume fraction, distribution pattern of porosity, geometric parameters, and ambient temperature rise significantly influence the structure’s nonlinear frequency and free vibration response.

Gas Insulated Metal Enclosed Transmission Line (GIL) Seismic Response Analysis

The seismic response analysis of a 550 kV gas-insulated metal-enclosed transmission line (GIL) is carried out to address the seismic performance issues in the design of the GIL. Firstly, the GIL is modeled in three dimensions, and the pre-stressed modal analysis is conducted to obtain the vibration characteristics of the GIL structure. Secondly, the seismic response spectrum analysis is conducted according to the national standard, and the seismic characteristics are obtained to meet the requirement of resisting an earthquake of magnitude 9, but there are problems of relatively large stress distribution and small safety coefficient of the brace. Finally, it is proposed to change the cross-section of the bracket to strengthen the stiffness of the bracket to improve the seismic performance of the GIL equipment, and simulations are carried out to verify the results, which show that increasing the cross-section of the bracket can improve the seismic performance of the equipment.

Seismic Response Analysis of Continuous Beam Bridges with Engineered Cementitious Composite (ECC) in Plastic Hinge Region

This study investigates the seismic performance of potential plastic hinge regions in small and medium-sized bridges using Engineered Cementitious Composite (ECC) concrete. A 4×40m continuous beam bridge is used as an example, with time-history analysis conducted using the OpenSees finite element software, and the type of concrete material in the cross-section of the bridge pier’s plastic hinge region is varied to analyze the structural natural vibration characteristics and seismic responses of the bridge structure under earthquake action. The time-history analysis of seismic motion shows that after replacing the bridge pier’s plastic hinge region with ECC, the stiffness of the bridge pier significantly decreases, and the natural vibration period of the bridge increases. Under the action of longitudinal earthquakes, the energy dissipation capacity and seismic performance of the bridge pier increase with the increase in ECC content in the plastic hinge region at the bottom of the bridge pier. Furthermore, under earthquake action, the concrete at the edge of the cross-section using ordinary concrete throughout cracks under tension, while the tensile stress in the cross-sections using different proportions of ECC concrete remains the same and does not crack under tension, remaining elastic under compression, which also reflects the good seismic performance of ECC concrete.

Evaluating structural strength and vibrational characteristics of silicon carbide incorporated adhesively bonded single lap joints

The adhesive bonding approach is widely used in assembling of spars, stringers, ailerons, flaps, and rudders in aircraft. The present research investigated the impact of silicon carbide (SiC) nanoparticle inclusion on the shear and free vibrational behaviour of adhesively bonded single lap joints (SLJ). The shear test results showed that the inclusion of 1.5 wt.% SiC in the epoxy resin enhanced the shear behaviour of adhesively bonded SLJ. Furthermore, the failure surfaces of adhesively bonded SiC-reinforced SLJ were examined using a field emission scanning electron microscope (FESEM). The microstructural investigation of the failure surface demonstrated that the development of rougher surfaces, plastic void enlargement, and formation of shear bands in the joint region had improved adhesion among GFRP adherends. Thus, the SiC-incorporated adhesively bonded SLJ had predominant cohesive failures. Meanwhile, the SiC-free lap joint had an adhesive failure due to lower adhesion. The vibrational results avowed that 1.5 wt.% SiC-incorporated adhesively bonded SLJ has higher natural frequencies. Results also affirmed that higher wt.% SiC-incorporated joint had better modal damping values due to nanoparticle accumulation, which increased the interaction between glass fiber reinforced polymer (GFRP) adherends.

Vibration IOT Control Algorithm for Steel Structures of Concrete Buildings with Elastic Boundary Constraints

Abstract Because of the influence of steel structure’s elastic properties in concrete buildings, the traditional vibration Internet of Things (IOT) control algorithm of steel structures has the problem of low control efficiency. Based on the research subject of concrete buildings, a corresponding steel structure model is established, and the corresponding vibration control standard is determined according to the characteristics of the model. In this model, the boundary elastic constraints of the steel structure are set according to its structural characteristics, and the vibration characteristics of the steel structure are analyzed under the constraints. The external vibration signal is simulated, and the response of the building’s steel structure under different signal excitations is observed. According to the response characteristics of the steel structure, the vibration controller is designed and installed, the real-time vibration signal is input into the controller, and finally the vibration control of steel structure of concrete building is realized. By comparison with the traditional vibration IOT control algorithm, it is concluded that the vibration control method designed by combining vibration frequency and vibration amplitude has smaller error and shorter time cost, that is, the designed vibration IOT control algorithm has more advantages in control efficiency.

Local Instability and Deformation Control of Steel Roof of Factory Building in a Smart City

Abstract The traditional control methods of instability and deformation of steel structure neglect the analysis of its natural vibration characteristics, which lead to the poor effect of hysteretic vibration of steel structure nodes, and the stability optimization of steel structure is not ideal. Therefore, a new method to control the local instability and deformation of the steel roof is proposed. According to the steel structure composition of the upper door rigid frame and the connection mode of the frame beam and column, the roof steel structure characteristics of the workshop are analyzed. Multi-order natural frequency method is used to obtain the cumulative modal mass contribution rate of steel structure and analyze the natural vibration characteristics of steel structure. Based on the characteristics of natural vibration and element transfer matrix, the local instability control method of roof steel structure is designed. Simulation of strong vibration, using space analysis of tall-building with wall-elements (SATWE) software analysis of strong vibration under elastic load state, to obtain the external deformation of steel structure, under simulation of vibration deformation control model. Taking a chemical plant as an example, a finite element model was established to simulate the vibration wave, and the numerical simulation results of plastic deformation resistance of steel structure were analyzed. The experimental results show that the proposed method can effectively enhance the stability of steel structure and reduce its deformation degree.

Molecular structure prediction, experimental and theoretical properties, and biological activities of (E)-5-nitro-3-(phenylimino) indolin-2-one- in-vitro against 60 lethal tumour cell lines

In this study an isatin derivative (E)-5-nitro-3-(phenylimino) indolin-2-one (5NPI) has been synthesized and examined utilizing quantum chemical calculations of DFT approach for structural optimization, electronic and vibrational characteristics. Functional groups have been detected using FT-IR spectra and compared with simulated spectra. To model UV–vis absorption and identify electronic characteristics in solvents and gas phase, TD-DFT computations have been performed. The GIAO technique was used to measure chemical shifting in NMR in several different solvents. Theoretical parameters coincide perfectly with experimental data. HOMO and LUMO band gaps reflect chemical activity and have satisfactory charge exchange inside the molecule. RDG analysis, topological and NBO investigations have been used to study weak intermolecular interactions. Reactive regions of the 5NPI compound have been determined using MEP and Fukui functions. NLO behavior has been computed using hyperpolarizability parameters. The anticancer activities of the compound 5NPI were evaluated from the National Cancer Institute (NCI), USA and subjected to in-silico analysis such as drug-likeness, ADMET and molecular docking. The compound 5NPI has been docked with 3RUX, 8ADA, 3TFU and 6TOJ proteins and showed moderate binding affinity as −7.14, −6.42, −6.68 and −8.41 kcal/mol respectively. Compound 5NPI is used as a lead molecule in the treatment of TB along with various tumors.

Structural vibration characteristics of the historical building in a nearby blasting test

The tunnel construction by the drill-and-blast method can have a significant impact on the adjacent buildings, especially the historical buildings with poor structural performances. Based on a special explosive case of Nanjing Metro Line 4, an in-situ blasting test for vibration safety evaluation on the Nanjing Drum Tower was carried out. According to the site geological investigation, the location of the blasting test was selected near the planned tunnel. 6 blasting was carried out in terms of sing-hole blasting and millisecond-delay blasting. The attenuation of the ground vibration and the structural vibration responses of the historical Drum Tower were analyzed. The test results also showed that the Nanjing Drum Tower was not damaged by this blasting test. For single-hole blasting tests, the peak particle velocity increased with the increasing of the explosive charge, but decreased remarkably when using the millisecond-delay blasting technology. The horizontal and vertical ground vibration attenuation patterns were consistent, which can be described by the Sadowski formula. The ground vibration response was dominated by the horizontal vibration, and the velocity amplification factor in the case of the single-hole test with a charge quantity of 400 g reached 2.4, which was observed the most remarkable amplification effect.