Finite Analysis Method Research Articles

Investigation on Vibro-acoustic Characteristics of High-speed Railway Steel-concrete Composite Bridge Based on the Combined FE-BE-SEA Method

This paper presents a combined finite element-boundary element-statistical energy analysis (FE-BE-SEA) method to predict the vibro-acoustic characteristics of high-speed railway steel-concrete composite (SCC) bridge. The train-track coupling model is firstly introduced to accurately determine the forces transmitted to bridge, which are then imported into the established FE-BE model and SEA model. Among them, the former is adopted to calculate the vibration response in full frequency band and acoustic response at 20∼200 Hz, while for the noise part at 200∼2000 Hz, the latter is utilized for calculation. The on-site testing is carried out simultaneously to collect the measured results, which are compared with the predicted ones, validating the reliability and accuracy of the proposed method. Finally, a thorough discussion is conducted on the acoustic contribution and parametric analysis. The results indicate that the dominant frequency bands of deck and web radiated noise are below and above 200 Hz, respectively, ranking first and second in terms of overall acoustic contribution, followed by the diaphragm and flange. Reducing train speed, installing elastic fasteners, as well as increasing web thickness can significantly mitigate the vibro-acoustic responses from SCC bridge, but the effective frequency ranges for vibration and noise reduction are slightly different.

Design of advanced steels by integrated computational materials engineering

AbstractThe integrated computational materials engineering (ICME) has achieved great success in accelerating the rational design and deployment of new materials. It is a new route of designing new materials and processes and highlighted by Materials Genome Initiative/Engineering that stresses the high‐throughput computation in addition to high‐throughput experimentation and materials informatics. This article presents a brief review on the basic theories and multi‐scale computational tools of ICME to design advanced steel grades, including the first‐principles calculations, the CALPHAD method (i.e., computational thermodynamics) fueled by dedicated databases, diffusion and phase‐field simulations, as well as finite analysis methods and machine learning. In the ICME scheme to deal with steels, the CALPHAD method is considered as the core to readily consider multi‐component systems and integrated to link the microscopic simulations (such as diffusion and phase field method to predict microstructure evolutions in response to external conditions) and macroscopic finite analysis method to deal with mechanical properties. Two applications are also presented to address the new routes to carry out materials design, especially for advanced steels.

Application of the finite analytic numerical method to a flow-dependent variational data assimilation

Application of the finite analytic numerical method to a flow-dependent variational data assimilation

Multi-physical Field Analysis Method for Enclosed Isolated Phase Busbar of Hydropower Station

In this paper, geometrical modelling and finite element multi-physical field analysis method are carried out for the actual layout of the enclosed isolated phase busbar (EIPB) of a hydropower station, for the horizontal and vertical connection parts that can hardly be considered in the analytical calculation process. The finite element model is able to accurately represent the main structure of the EIPB by reasonably simplifying some of the components. Meanwhile, the finite element model incorporates the coupling of magnetic field and transient structural field, allowing for analysis of the magnetic field distribution, stress-strain distribution, modal analysis, and harmonic response of each component of the EIPB. It is capable of analyzing the vibration response of the complex horizontal-vertical structure EIPB under different excitations. This method can overcome the limitations of analytical calculation methods in calculating complex structure EIPBs. It can also provide valuable guidance for the structural optimization design of future EIPBs.

A novel numerical method to evaluate the heat transfer characteristics of complicated CICC structures

In this article, we propose a numerical model for calculating the external heat transfer coefficient between the bundle region and its wall for cables in conduit conductor (CICC). With the assumption of local thermal equilibrium, one macro equation describing the steady heat transfer on the cross section of the CICC can be obtained. A key parameter, the effective transverse thermal conductivity keff, which takes the contribution of both strands and flowing fluid into consideration, is introduced. To calculate the effective transverse thermal conductivity keff, we first obtain the true distribution of different phases (fluid, copper and superconducting material) on a cross section of CICC with the help of the image recognition technique. Based on this, the value of the effective transverse thermal conductivity keff can be calculated numerically. Due to the large difference among the component thermal conductivities (at 4.5 K, typical values of the thermal conductivity of liquid helium, superconducting material and copper are kHe=0.024Wm−1K−1, kNb3Sn=0.04Wm−1K−1 and kCu=708Wm−1K−1; and the maximal ratio of thermal conductivity can be as high as about 30,000), the high-performance finite analytical method (FAM) is recommended to calculate keff. After obtaining the effective transverse thermal conductivity keff of the bundle region, the heat transfer coefficient can be calculated directly by solving a simple Poisson equation under proper boundary conditions. Two case studies are performed, including the JT-60 Super Advanced (JT-60SA) CICC and the dual channel International Thermonuclear Experimental Reactor, Toroidal Field Performance Sample (ITER-TFPS). The calculated values of heat transfer coefficient are consistent with the experimental results, which verifies our proposed model.

Finite Element Analysis of Aluminum Based R22 Car Wheel Design Modification

The wheels are one of the main parts of the vehicle. To make car wheels, manufacturers must complete several stages. Especially in the design of the wheels. This study aims to determine the comparative value of three different types of wheels with the same material using aluminum type 6061-T6 (SS). We will test the three-wheel models, namely model 1, model 2, and model 3, with a force of 3000 N and a pressure of 800 N to compare their performance. This test uses Solidworks 2019 software with the finite electronic analysis (FEA) method. The results obtained are the value of Von Misses stress, resulting displacement, equivalent strain and its deformation, and factor of safety. The dimensions of the wheels are 22 inches. The results of the best Model 3 alloy wheel research indicate that the design process is easier. These wheels have a Von Misses stress value of 11.02 MPa with a resulting displacement value of 0.021 mm, an equivalent strain of 0.000096, a safety factor of 25, and a deformation value of 1. Based on these results, model 3 alloy wheels are safe.

Effect of train traction on the wheel polygonal wear of high-speed trains

High-order polygonal wear of wheels is one of the most severe technical challenges for China's high-speed trains at present, and its formation mechanism has not been thoroughly understood. The effect of train traction on the wheel polygonal wear of high-speed trains was studied based on a wheel/rail rolling contact finite element model. The frequency domain characteristics of unstable vibration of the wheel/rail system under rolling/sliding contact were studied by using the finite element complex modal analysis method. We also examined wheel/rail contact forces and friction in the time domain. The cause of the high-order polygonal wear of Chinese high-speed train wheels was revealed. The effect of the vehicle speed and the wheel diameter on wheel polygonal wear were investigated. The results show: the friction-induced vibration of the wheel/rail system will be excited when the rolling/sliding contact between the wheel and rail. The radial zoom modal of the wheel is an unstable mode, which is the main cause of the 21-22 order polygonal wear of the high-speed train wheels in China. Additionally, vehicle speed has a linear relationship with the order of polygonal wear. Reducing the vehicle speed helps to control the polygonal wear of the wheels. Wheels of different diameters exhibit varying degrees of polygonal wear, with smaller wheels being more resistant to friction-induced vibrations.

Finite analytical method on corner‐point grid for fluid flow in heterogeneous porous media

AbstractThe three‐dimensional (3D) corner‐point grid system, as an industrial standard, has been widely used in oil reservoir geological modeling and numerical simulation due to its versatility compared to traditional orthogonal grids. The finite analytical method (FAM) is proposed for corner‐point grid systems in this article, which can greatly improve the simulation accuracy, especially for strongly heterogeneous porous media. Based on the approximate analytical solution around the edge of the corner‐point cells, the internodal transmissibility of two adjacent cells is recalculated to replace the traditional one. The traditional internodal transmissibility is calculated based on the harmonic mean of the permeabilities of the two adjacent cells, which will greatly underestimate the transmissibility and lead to an uncontrollable error as the strength of heterogeneity increases. The proposed FAM can calculate the internodal transmissibility rather accurately, and its accuracy is irrelevant to the strength of the heterogeneity, which is the main advantage of FAM. Numerical tests show that the simulation results of the proposed FAM converge much faster than the traditional method as the cells are refined. The proposed FAM can be easily extended to the simulation of multiphase flow and be easily embedded in commercial reservoir numerical simulation software.

Parameters calculation method of energetic model for symmetrical static hysteresis loop and asymmetrical minor loop

PurposeThis paper aims to propose an energetic model parameter calculation method for predicting the materials’ symmetrical static hysteresis loop and asymmetrical minor loop to improve the accuracy of electromagnetic analysis of equipment.Design/methodology/approachFor predicting the symmetrical static hysteresis loop, this paper deduces the functional relationship between magnetic flux density and energetic model parameters based on the materials’ magnetization mechanism. It realizes the efficient and accurate symmetrical static hysteresis loop prediction under different magnetizations. For predicting the asymmetrical minor loop, a new algorithm is proposed that updates the energetic model parameters of the asymmetrical minor loop to consider the return-point memory effect.FindingsThe comparison of simulation and experimental results verifies that the proposed parameters calculation method has high accuracy and strong universality.Originality/valueThe proposed parameter calculation method improves the existing parameter calculation method’s problem of relying on too much experimental data and inaccuracy. Consequently, the presented work facilitates the application of the finite element electromagnetic field analysis method coupling the hysteresis model.

A finite layer analysis method proposed for energy pile modeling under coupled thermo-mechanical loads

This study proposes a new hybrid analytical and numerical approach to analyze energy piles by coupling thermal and mechanical loads. Conceived through the finite unit method, the Finite Layer Analysis Method (FLM) boasts promising results when applied to energy piles in soil, which is typically layered or multilayer mediums. This methodology effectively reduces a complex, three-dimensional geotechnical problem to two dimensions, yielding marked improvements in computational efficiency. The FLM for energy pile consists of temperature field calculation and thermo-mechanical coupling calculation, for which the theory and derivation are carefully introduced and elaborated. To validate the accuracy and robustness of the newly proposed FLM method, both the temperature field calculation and the thermo-mechanical coupling calculation are verified meticulously with the finite-length heat source analysis theory, together with the Finite Element results. The validations are also performed against a variety of field trial data including those from London and Lausanne tests.

Intelligent Optimization Design of a Phononic Crystal Air-Coupled Ultrasound Transducer.

To further improve the operational performance of a phononic crystal air-coupled ultrasonic transducer while reducing the number of simulations, an intelligent optimization design strategy is proposed by combining finite element simulation analysis and artificial intelligence (AI) methods. In the proposed strategy, the structural design parameters of 1-3 piezoelectric composites and acoustic impedance gradient matching layer are sampled using the optimal Latin hypercube sampling (OLHS) method. Moreover, the COMSOL software is utilized to calculate the performance parameters of the transducer. Based on the simulation data, a radial basis function neural network (RBFNN) model is trained to establish the relationship between the design parameters and the performance parameters. The accuracy of the approximation model is verified through linear regression plots and statistical methods. Finally, the NSGA-II algorithm is used to determine the design parameters of the transducer. After optimization, the band gap widths of the piezoelectric composites and acoustic impedance gradient matching layer are increased by 16 kHz and 13.5 kHz, respectively. Additionally, the -6 dB bandwidth of the transducer is expanded by 11.5%. The simulation results and experimental results are consistent with the design objectives, which confirms the effectiveness of the design strategy. This work provides a feasible strategy for the design of high-performance air-coupled ultrasonic transducers, which is of great significance for the development of non-destructive testing technology.

Estimation Method for an In Situ Stress Field along a Super-Long and Deep-Buried Tunnel and Its Application

Aiming at some stress-induced failure phenomena in surrounding rock that occur during the construction of super-long and deep-buried tunnels, a method for estimating the in situ stress in the tunnels based on multivariate information integration is proposed, which uses a small amount of in situ stress measurement, stereographic projection technology, and a numerical simulation method. Firstly, by conducting a macroscopic analysis of the regional geological structure, topography, and pre-excavated small tunnels (such as exploration of adits and pilot tunnels), the strength of the tectonic stress field and the orientation of the principal stresses in the tunnel sections are preliminarily determined. Secondly, the reliability of the in situ stress measurement data were analyzed using full-space stereographic projection and the plane stress projection method. Then, some representative measurement points that reflected the distribution characteristics of in situ stress in the project area, on the whole, were determined. Thirdly, the finite difference (FDM) and multiple regression analysis (MRA) methods were used to inverse the in situ stress field in the project area. The proposed method was applied to a super-long and deep-buried tunnel project in Qinling, and the in situ stress distribution characteristics of the tunnel sections at different mileages were obtained. The results show that both the calculated principal stress values and the azimuth angle of the maximum horizontal principal stress are in good agreement with the measured ones, indicating that the method used in this study is reasonable. Finally, the typical surrounding rock failure phenomena encountered during the excavation of the project were investigated, and targeted treatment measures were proposed. The research results can provide references for support design and disaster management of surrounding rock in deep-buried long tunnels.

Fault diagnosis in rotors using adaptive neuro-fuzzy inference systems

Condition monitoring of rotor dynamic systems is emerging research in recent years. The proposed research is a condition monitoring methodology based on Adaptive Neuro-Fuzzy Inference Systems (ANFIS) to detect the open cracks in the single disk rotor-bearing system. Condition monitoring systems generally requires a large amount of processed data for a specific output. The proposed methodology uses the same input data to train two different ANFIS without compromising on the accuracy of the results. The response of rotor-bearing system is generated by using finite element model analysis and harmonic balance method. All simulations are programed in MATLAB programing software. The effects of open groove or wedge cracks (notch crack) on natural frequency and resultant operational response (nodal deflections) of rotor-bearing systems are analyzed. Response orbit at 3× resonance of first natural frequency is analyzed to diagnose the crack in rotor shaft. Resultant operational response (Absolute response due to crack) is recorded for various crack locations and crack depths. Continuous Wavelet Transforms (CWT) are used, to extract the features from operational deflection shape (from operational response) to detect the crack location and their severity (depth). Location of maximum CWT coefficients provides the close vicinity of crack and their magnitude provides the severity of crack. Crack as small as 1% of crack depth to diameter ratio can be identified by CWT. ANFIS are used as a machine condition monitoring methodology to diagnose the crack and predict the crack parameters (crack location and depth). Two Parallel ANFIS are trained to predict the crack parameters. ANFIS-1 is trained for crack location and ANFIS-2 is trained for crack depth. CWT coefficients, maximum response amplitude at the vicinity of crack, and first three natural frequencies are provided as input to both ANFIS-1 and ANFIS-2 for training. The trained condition monitoring methodology accurately detects (predict) the crack location (ANFIS-1) and crack depth (ANFIS-2) with root mean squared error of 0.0833 and 0.137916 respectively.

Cyclic Behavior of Autoclaved Aerated Concrete External Panel with New Connector.

In this paper, a new slip-type crossing connector is proposed for autoclaved aerated concrete (ALC) panels with steel frames, and the proposed connector is also studied deeply in terms of seismic performance. The research included pseudo-static tests and finite element simulations. First, the seismic performance of slip-type crossing connectors and standard L-hooked bolts was studied comparatively, including the stability, bearing capacity, stiffness, energy dissipation, and hysteresis performance. ABAQUS 2020 software was used to establish finite element models, and the results of the experiments were verified with simulations on the basis. According to the simulations, a parameter analysis of connector optimization was carried out. The effects of connector thickness and connector plate length on the seismic performance were further investigated. From the experimental and simulation results, the slip-type crossing connector has excellent performance and good assembly efficiency, it can improve the deficiencies of the existing connectors. The comparison demonstrated that the slip-type crossing connector has a complete hysteresis curve, a high energy dissipation capacity, and a 9.7% increase in bearing capacity. The appropriate reduction in connector thickness and plate length can ensure superior seismic performance while saving resources. The finite analysis method can guide the design and implementation of new external ALC panel connectors.

Finite Element Analysis of Continuous Plates Using a High-Performance Programming Language (MATLAB)

This paper uses MATLAB, a finite element software program to compare the results of several finite analysis methods for continuous plates and check the degree of correlation with the exact values obtained by Timoshenko (1959) and Cheung (1996). The results showed little or no significant difference between plates in finite elements. Two different finite Numerical techniques are used. The Finite Strip and Exact methods and their results are compared to the results from the MATLAB program. Finite element analysis (FEA) workflow using MATLAB includes generation of meshes, geometry creation, defining physics of load, initial conditions and boundary problems, calculation, and results from visualization. FEA is a very general approach for solving Equations in science and engineering. This work offers solutions to the increasing errors associated with several other numerical methods when solving any equations of plates (сontinuous). It makes it easier to calculate and design larger structures through geometry discretization of plates and plains into more minor elements.

Application of the Fractional Calculus in Pharmacokinetic Compartmental Modeling

In this study, we present the application of fractional calculus (FC) in biomedicine. We present three different integer order pharmacokinetic models which are widely used in cancer therapy with two and three compartments and we solve them numerically and analytically to demonstrate the absorption, distribution, metabolism, and excretion (ADME) of drug in different tissues. Since tumor cells interactions are systems with memory, the fractional-order framework is a better approach to model the cancer phenomena rather than ordinary and delay differential equations. Therefore, the nonstandard finite difference analysis or NSFD method following the Grunwald-Letinkov discretization may be applied to discretize the model and obtain the fractional-order form to describe the fractal processes of drug movement in body. It will be of great significance to implement a simple and efficient numerical method to solve these fractional-order models. Therefore, numerical methods using finite difference scheme has been carried out to derive the numerical solution of fractional-order two and tri-compartmental pharmacokinetic models for oral drug administration. This study shows that the fractional-order modeling extends the capabilities of the integer order model into the generalized domain of fractional calculus. In addition, the fractional-order modeling gives more power to control the dynamical behaviors of (ADME) process in different tissues because the order of fractional derivative may be used as a new control parameter to extract the variety of governing classes on the non local behaviors of a model, however, the integer order operator only deals with the local and integer order domain. As a matter of fact, NSFD may be used as an effective and very easy method to implement for this type application, and it provides a convenient framework for solving the proposed fractional-order models.

A Gas Diffusion Analysis Method for Simulating Surface Nitrous Oxide Emissions in Soil Gas Concentrations Measurement

The detection of low gas concentrations from the soil surface demands expensive high-precision devices to estimate nitrous oxide (N2O) flux. As the prevalence of N2O concentration in the soil atmosphere is higher than its surface, the present study aimed to simulate N2O surface flux (CF) from soil gas measured in a soil-interred silicone diffusion cell using a low-cost device. The methodological steps included the determination of the diffusion coefficient of silicone membrane (Dslcn), the measurement of the temporal variations in the N2O gas in the soil (Csi) and on the surface (MF), and the development of a simulation process for predicting CF. Two experiments varying the procedure and periods of soil moisture saturation in each fertilized soil sample were conducted to detect Csi and MF. Using Dslcn and Csi, the variations in the soil gas (Csoil) were predicted by solving the diffusion equation using the implicit finite difference analysis method. Similarly, using six soil gas diffusivity models, the CF values were simulated from Csoil. For both experiments, statistical tests confirmed the good agreement of CF with MF for soil gas diffusivity models 4 and 5. We suggest that the tested simulation method is appropriate for predicting N2O surface emissions.

Design and Analysis of Coreless Axial Flux Permanent Magnet Machine with Novel Composite Structure Coils

In this paper, a type of novel composite structure coil applied in the coreless stator is proposed and studied to improve the output performance and efficiency of the axial flux permanent magnet (AFPM) machine. In which the effective conductor is changed to be wedge-shaped by the rolling technology so that the turns of coils and filling factor can be further increased, and the ends are kept in the cylinder with a larger diameter to reduce the DC copper loss. Meanwhile, the air region between the double rotors of the machine is also modified to be wedge-shaped, which fully matches the proposed coils and shortens the air gap length. The advantages of performance can be verified by the three-dimensional (3D) finite element analysis (FEA) and analytical method so that the output characteristics of no-load and load can be improved, and the DC copper loss and eddy current loss of coils can be reduced. The coreless AFPM machine finally performs a high efficiency of 95.34% according to these valuable optimizations.

Study on the Response of Staggered Floor Isolated Structures in Mountainous Areas under Three-Dimensional Earthquakes

As coal mines are susceptible to safety accidents due to earthquakes, the requirements for structures in coal mining areas such as fire control centers and hospitals are higher, so base isolated structures, including staggered isolated structures, adapted to mountainous terrain are used in mining areas. The staggered floor isolated structure is a kind of isolated structure in mountainous areas which developed from the base-isolated structure. The theoretical research on staggered isolated structures is relatively few, and the theoretical research lags behind the practical application of engineering. In this paper, three staggered floor isolated structures with different heights of staggered floors are established. The responses of structures under one-dimensional, two-dimensional, and three-dimensional earthquakes are analyzed by the finite element dynamic time-history analysis method. The structural torsion, interstory shear force, maximum axial force, and floor displacement of the structure are compared. Due to the asymmetric characteristics of the staggered floor isolated structure, the center of stiffness of the staggered floor isolated structure deviates from the center of mass, which produces not only horizontal vibration but also obvious torsional vibration. The input of earthquakes in different dimensions also makes a difference in the response of the structure. The location between the upper isolated layer and the first floor above the upper isolated layer is a weak point of the structure. The results obtained in this study are distinguished from traditional basic isolated structures, which supplements the theoretical research of the staggered isolated structure.

Finite Element Analysis on Mirco-Steel Tubular Pile Refilled Concrete Reinforced Structure Foundation

Steel tubular pile technology is an effective method to reinforced foundation in retrofitting of existing buildings. Mirco-steel tubular pile is constructed with concrete filled steel tubular, the infilled concrete could reinforced the strength of mirco-pile and prevented the local-buckling of steel tubular. According to ANSYS software, a mode of finite element analysis was built with some function between mirco-pile and soil foundation, the mode was confirmed by some test data. The slenderness ratio and material strength were two important factors for the bearing capability of mirco-pile with concrete filled steel tubular. The bearing capability and some influence factors on concrete filled mirco-steel tubular piles were analyzed by factors analysis method. The mode of finite element analysis and factors analysis method on were applied for reinforced building foundation and referred to other application of concrete filled steel tubular.