Numerical Finite Element Method Research Articles

Assessment of the beam configuration effects on designed beam–column connection structures using FE methodology based on experimental benchmarking

Abstract Purpose This article aims to investigate the structural behavior of beam–column joints subjected to axial force. The geometry used is the addition of a number of beam connections to the column, and the differences in the numbers of beams used are 1, 2, 4, and 4, denoted as V1, V2, V3, and V4, respectively. Design/methodology/approach In this work, the analysis was performed using the numerical finite element method with ABAQUS software. A benchmarking analysis was also conducted to validate the numerical results. Findings Several numerical simulations showed that of the variations tested, the V2 model demonstrated the highest force value among the four test models, at 130.883 kN. The displacement caused by the force was 227.32 mm, which was the lowest value among the four test models. On the other hand, the V3 model received the smallest force value among the four test models, at 24.576 kN, with a displacement of 227.49 mm. The displacement value was greater than that for the V2 model, further indicating that the V2 model was the stiffest of the four models tested. Originality/value This study shows that the influence of beam–column joint geometry is not limited to double-extended end-plate bolted connections.

Numerical simulation analysis of the rolling process based on the particle swarm hybrid algorithm

ABSTRACT It is very complicated to study the three-dimensional deformation of metal during rolling. The conventional finite element numerical analysis method generally adopts a fixed algorithm to calculate the whole rolling process. This method consumes huge computing power and sacrifices some computing accuracy. In this paper, according to the characteristics of different rolling stages, on the basis of considering the degree of metal deformation, a particle swarm hybrid algorithm with adaptive weight-learning factor is proposed.The Zoutendijk algorithm, Rosen algorithm, Wolfe algorithm and particle swarm hybrid algorithm are used to numerically simulate the rolling transverse thickness distribution. The accuracy of the rolling model and the particle swarm hybrid algorithm are verified. The influence of work roll edge contact and asymmetric roll bending on the deformation of rolling metal is analysed based on particle swarm mixing algorithm.

Dynamic stability of slightly curved tensioned pipe conveying pressurized hot two phase fluid resting on non uniform foundation

The dynamic stability of slightly curved tensioned pipes conveying pressurized two phase fluid, under thermal loadings are investigated in this paper. Furthermore, these pipes are resting on nonuniform elastic foundations. The equation of motion of the system is derived using the extended Hamilton’s principle for open dynamic systems and considering the Euler–Bernoulli theory for slender beams. The free vibration and the effects of two phase fluid flow, geometric imperfections, thermal, tension and pressure on the pipe system resting on nonuniform foundations are investigated numerically. Three different boundary conditions (BC) are considered, namely simply-simply (SS) supported, simply-clamped (SC) supported and clamped-clamped (CC) supported. The numerical method of Finite Element was used on the partial differential equation. This method is used to accurately predict steady state natural frequency responses of a dynamical system through several numerical investigations. It was found that the stability of slightly curved pipes conveying two phase flow are significantly affected by the boundary condition. It is shown that the initial curvature term increases the critical velocities for all the nine modes considered, the increase is significant in the first and second critical velocities compared to the other modes. Initial curvature effect is more pronounced in simple supported ends. Further-more the influence of the fluid velocity, temperature, pressure and axial tension is analysed; the results show that the vibration frequency decreases when the fluid velocity, temperature, and pressure increase or the axial tension decreases, and the critical fluid velocity decreases when the temperature and pressure increase or the axial tension decreases. For the pipe on nonuniform foundation, an increased stiffness leads to an increased in the first critical velocity for all the BC. However, the pattern of the increment depends on the attachment parameter, initial curvature, and the vapour quality. Some of these results are completely absent in pipes conveying single flows.

Numerical simulation of thermal effects in laser diode end-pumped solid-state lasers utilizing finite element method

Based on the finite element numerical analysis method, the temperature field distribution in the crystal with time is simulated by using the PDE-tool in MATLAB. The critical factors affecting the crystal transient temperature distribution are simulated and analyzed. According to the simulation parameters and results, a simplified method for solving the transient heat conduction equation is proposed. The transient thermal focal length is solved to obtain its distribution expression and an approximate analytical solution. The results provide a theoretical basis for the thermal analysis process of suppressing or utilizing the transient thermal effect in high-energy solid-state lasers.

Numerical simulation of the palaeotectonic stress field and prediction of the natural fracture distribution in shale gas reservoirs: A case study in the Longmaxi Formation of the Luzhou area, southern Sichuan Basin, China

Natural fractures have an important relationship with shale gas production. This study selected the reservoir of the Wufeng‐Longmaxi Formation in Luzhou in southern Sichuan as an example. Based on the seismic reflection map of the formation, using the mechanical parameters obtained from the core sample experiment and using the finite element numerical simulation method, a three‐dimensional geological model is established, the tectonic stress field is inverted and the fracture distribution is predicted according to the Mohr‐Coulomb fracture criterion of the rock fracture, which provides theoretical support for the subsequent well pattern layout and is conducive to improving the efficiency of shale gas exploration and development. The analysis shows that the study area is dominated by NE reverse faults, with an inclination of more than 40°. The core observation results show that the filling degree of fractures is relatively high, and the width is mostly less than 1 mm, mainly caused by tectonic shear fractures. The tectonic stress in the sedimentary belt where the syncline structure is deeply buried is higher, the stress in the northwest and southeast tectonic ridges is relatively low, and the differential stress in the northeast tectonic ridge and near the fault is high. The NE fault and the surrounding rock mass have the highest fracture degree; the fracture proximity coefficient is >1.5 and the fractures are the most developed. The degree of fracture development in the area with a gentle structure is relatively low, but it is far from large faults, which is conducive to preserving shale gas.

Force Analysis of Circular Diaphragm Wall Based on Circular Cylindrical Shell Theory

In order to make up for the shortcomings of existing theory calculation methods for circular diaphragm walls, an alternative calculation method was developed with a clear concept based on the circular cylindrical shell theory and superposition principle in elasticity and named the circular cylindrical shell theory calculation method (CCSTCM). We took the north anchorage circular foundation pit of G3 Tongling Yangtze River Highway and Railway Bridge as an example and calculated and analyzed it by the proposed CCSTCM, finite element numerical simulation method (FENSM) and site monitoring. As a result, we obtained the radial displacement, circumferential stress and vertical bending moment of the circular diaphragm wall, and then summarized their regularities. By researching the results of the CCSTCM (TCR), the results of the FENSM (NSR) and the results of the site monitoring (SMR), the following conclusions could be drawn: the numerical calculation model established was reasonable; the variation trends of the data curves of the TCR were highly similar to those of the NSR and SMR; and the TCR were slightly larger than the NSR but slightly smaller than the SMR, and closer to the SMR in general. Finally, the proposed CCSTCM was proven to be correct and applicable and could be used in similar circular diaphragm wall projects.

Ensuring a safe geomechanical state of the rock mass surrounding the mine workings in the Karaganda coal basin, Kazakhstan

Purpose. The research purpose is to determine the instability zones in the host rocks and the dynamics of propagation of active fracturing zones to ensure the stability of the rock mass surrounding the mine workings. Methods. The research uses a set of analytical and experimental studies to determine the dynamics of the deformation process development in the coal-rock mass surrounding the mine workings. Mathematical modeling of the stress-strain state of the rock mass surrounding the active extraction workings is performed using the numerical method of finite elements in modern AN-SYS, Mergel and KMS-III software products. Findings. The influence has been studied of the mine working section shape and the coal seam dip angle on the value of the maximum stresses that arise in the rock mass when the mine working is fastened with the roof-bolt support. The instability zones in the host rocks and the dynamics of propagation of active fracturing zones have been determined both ahead of the front of the conducted mine working and on its sides for rocks of different strength. Originality. For the conditions of the Karaganda coal basin, the dependence of a change in the development of conventional inelastic deformation zones (CIDZ) on the host rock strength has been revealed. The influence of the coal seam dip angle on the dynamics of stratifications around preparatory working has also been substantiated. In addition, new data have been obtained on the influence of the roof rock strength on the stratification of the rock mass surrounding the mine working. Practical implications. By determining instability zones in the host rocks and the dynamics of propagation of active fracturing zones, it is possible to control geomechanical processes in the border rock mass of a mine working and influence it in order to prevent the occurrence of negative rock pressure manifestations. The data obtained are the basis for the development of recommendations on the use of roof-bolting technology for fastening extraction workings to ensure their stability and reduce the cost of their operation.

Seismic Wave Excitation of Mature Oil Reservoirs for Green EOR Technology

Elastic wave-based oil mobilization of residual oil in heterogeneous reservoirs is a viable, low-cost, and green technology method of enhanced oil recovery (EOR). Applications for elastic (seismic) waves at the reservoir scale are currently in the preliminary stages of investigation and development. We employ a two-layer numerical finite element method (FEM) in this research to investigate the possibility of effective propagation of seismic waves in the low permeability area of a mature oil reservoir when seismic stress load is delivered to the rock matrix via a downhole source. The purpose of this research is to evaluate the potential of fluid and rock matrix displacement amplitudes for crossflow generation in a mature oil reservoir. In a low permeability formation, the numerical results reveal that, as the observation radius approaches the reservoir boundary, the rock matrix time-domain displacement performs better as a wave propagation parameter than the pore fluid displacement. However, crossflow oscillations at a peak mesoscopic frequency of 3.0 Hz produce an instantaneous oil transfer rate (recovery rate) of 2.5% (bypassed oil) from the low permeability area. This method can be used in combination with water flooding to recover more oil from both high and low-permeability areas. Mesoscopic attenuation frequency can therefore be utilized as one of the indicators to assess oil recovery in heterogeneous oil reservoirs.

Study on the ground impact vibration intensity model of high energy warhead explosion

Introduction: In the warhead explosion process, the ground impact vibration intensity will directly affect the target buildings and instruments safety, and it is also of great significance to accurately evaluate the ammunition explosion damage power.Methods: In this study, the finite element numerical simulation method was used to analyze the explosion shock wave pressure and ground shock vibration velocity of TNT explosive with a mass of 100 kg∼1000 kg, and the ground transmission medium of sandy soil, C35 and C140 concrete, and the shock wave pressure and ground shock vibration velocity propagation and distribution law was clarified. Based on the explosion similarity law and dimensional analysis method, a ground impact vibration velocity theoretical calculation model with clear physical significance is established by introducing the property ground propagation medium parameters, taking into account the factors affecting the ground impact vibration velocity.Results: The model calculation accuracy is verified by the measured data. The verification results show that the model calculation accuracy is higher than 91.8%, which improves the calculation accuracy of the explosion site ground impact vibration velocity.Discussion: This research provides more accurate and scientific theory and data support for the ammunition explosion damage power evaluation, and provides a reference for the shock and vibration resistance performance design of instruments, equipment and buildings. It has strong engineering application value.

Study on the Influence of Earthquakes with Different Frequency Content on the Peak Liquid Sloshing Wave Height of Liquid Storage Tank

Liquid storage tank is an irreplaceable and extremely important vessel structure used to store liquid medium. In earthquake disaster, the liquid storage tank will not only be seriously damaged directly, but also cause serious secondary disasters, such as fire, explosion, poisoning, nuclear radiation, etc. The peak liquid sloshing wave height is an important reference index to judge whether the seismic design of the liquid storage tank is reasonable or not. The ratio of peak ground acceleration to peak ground velocity of the earthquake records (shown by A/V ratio) can well represent the characteristics of frequency content of earthquake records. In this paper, the finite element numerical simulation method is used to analyze the seismic response of six rectangular concrete tanks with different liquid heights, and their respective peak liquid sloshing wave heights are calculated. Nine seismic records with different A/V ratios are used, which are low frequency category, medium frequency category and high frequency category and there are three records in each category. At the same time, the equation in Eurocode 8 is used to calculate the peak liquid sloshing wave height of each tank for comparative study. The study results show that the peak liquid sloshing wave height calculated by the Eurocode 8 is greater than that calculated by the finite element method under low frequency and medium frequency earthquake records, indicating that Eurocode 8 is conducive to the preliminary design of the seismic performance of the liquid storage tank. However, in the case of high frequency earthquake records, the calculation result of the finite element method is larger than that of the equation in Eurocode 8. The peak liquid sloshing wave height of the liquid storage tank is more sensitive to the earthquakes with high frequency content, and the Eurocode 8 underestimates the impact of high frequency seismic response on the liquid storage tank.

Numerical Study on the Coupling Effect on a Retaining Structure of a Complex Deep Foundation Pit Group Excavation in a Soft-Soil Area

Based on the complex deep foundation pit group process of the Huimin Avenue Comprehensive Reconstruction Project in Nanjing, the finite element numerical simulation method is used to analyze the deformation characteristics of the retaining structure and the coupling effect between foundation pits during the whole process of excavation and support construction of the complex foundation pit group. Meanwhile, the differences in the deformation characteristics and coupling effects of the retaining structure under different construction time sequence schemes of the foundation pit group are studied. Finally, some suggestions are put forward for the monitoring and construction in this project, which provides a reference case for the design and construction of similar foundation pit groups.

Finite Element Analysis of Acoustic Performance of Water-filled Helmholtz Resonator with the Effect of Elastic Cavity Walls

Water-filled Helmholtz resonator is a primary means to reduce the hydrodynamic noise of pump and valve in naval vessels. The predicted acoustic performance of water-filled Helmholtz resonators with the effect of elasticity of cavity walls using finite element method is compared with theoretical and experimental results in references, which demonstrated the applicability and accuracy of the finite element numerical method. And then, the effect of thickness and materials of cavity walls on resonance frequency and transmission loss of resonators is discussed, including the comparison of rigid and elastic cavity walls predictions simultaneously. The results of the discussion in this paper show that the acoustic performance of water-filled Helmholtz resonators is influenced by the elasticity of cavity walls to a great extent, which must be taken into consideration in the process of design.

Temperature distribution of an SG-DBR laser cooled by a thermoelectric cooler

We introduce a one-dimensional analytical model to determine the steady-state thermal behavior of a sampled grating distributed Bragg reflector laser coupled to a thermoelectric element cooler. The governing equations are a system of ordinary differential equations that can be solved analytically. This method can easily be used when the laser is integrated with more functional elements, e. g., semiconductor optical amplifiers and amplitude modulators. The results are verified by the numerical finite element method and experimental data reported by other researchers. A comparison between the results of the analytical and numerical methods reveals the high consistency between them.

Landslide mechanism and stability of an open-pit slope: The Manglai open-pit coal mine

A clear understanding of landslide mechanisms and stability analyses is of great significance for landslide monitoring, prediction, and control. A large-scale end wall landslide occurred and its area reached 47,752 m2 on August 7–20, 2020, in the Manglai open-pit coal mine, China. In this paper, the engineering geological survey, mechanical test, large-deformation finite element numerical method, limit equilibrium method and analytical formula are used to analyze how the groundwater level rise caused this end wall failure and landslide. The engineering geological conditions, hydrogeological conditions, landslide activity signs and physical and mechanical parameter calibration of the sliding mass are investigated in detail and tested. Three-dimensional and two-dimensional numerical models of slopes are established, and an analytical formula calculation method to calculate the factor of safety (FoS) is proposed when sliding cracks are located on the top and toe of a slope. The results indicate that the fault fracture zone, soft strata, continuous heavy rainfall, and groundwater were the main contributors to this landslide. The three-dimensional numerical calculation results are consistent with the deformation and failure process of the slope observed in the field, which shows a retrogressive progressive failure mode. The calculation results of SLOPE/W and the analytical formula are consistent; i.e., when the groundwater level rises to +950, the stability of the end wall reaches the critical stability state. With the passage of time, the creep of the sliding surface accelerates until the entire end wall landslide.

Auxetics among Two-Layered Composites Made of Cubic Crystals. Analytical and Numerical Analysis

The results of calculations of the effective Young's modulus of longitudinally stretched twolayered plates made of identically oriented cubic crystals are presented on the basis of analytical analysis and the numerical finite element method. Analytical dependences of effective Young's modulus on Young's moduli and Poisson's ratios of crystals in layers are presented. Combinations of pairs of crystals with a significant deviation of the effective characteristics from ones found by the rule of mixtures are determined. The dependences of the effective Young's moduli on extreme values of the Young's moduli and Poisson's ratios of crystals in layers are established. They are presented graphically, and in some cases are reflected in the form of a table.

An Optimized Dental Implant Model Using Finite Element Analysis and Design of Experiment

Purpose: To develop, analyze, and optimize a dental implant by considering square threads and varying the thread dimensions to obtain an optimal shape. Materials and Methods: For this study, finite element analysis (FEA) and numerical optimization method were integrated to develop a mathematical model. The critical parameters of dental implants were studied, and an optimized shape was obtained using response surface method (RSM) and design of experiment (DOE). The simulated results were then compared to the predicted values under optimal conditions. Results: Using the one-factor RSM design model for the dental implant and a vertical compressive load of 450 N for testing, the optimal depth to width ratio for the thread was 0.7 in order to achieve the minimum von Mises and shear stress. Conclusion: The buttress thread was found to be the optimal shape for achieving the lowest von Mises and shear stress compared to square threads, and the thread parameters were calculated accordingly, with a thread depth 0.45 times the pitch, a width 0.3 times the pitch, and a thread angle of 17 degrees. Also, due to the constant diameter of the implant, common 4-mm diameter abutments can be used interchangeably.

Research on optimization strategy of transformer economic operation mode considering digital twin technology

Considering the overall environment of the power field, power transformer is one of the most important energy consuming devices in the substation, and the digital analysis technology of power transformer carbon footprint has become one of the hot issues. Taking a certain brand power transformer as an example, the no-load loss, load loss and stray loss of power transformer under different load conditions are calculated and analyzed by using electromagnetic finite element numerical analysis method, and then the digital twin model of power transformer is built. Combined with the digital twin model of power transformer, the carbon footprint of transformer is analyzed. Finally, the economic load coefficient of transformer is determined, and the optimal economic operation mode of substation is established. This method can provide a scientific basis for the construction of digital, low-carbon and energy-saving substations, while meeting the optimal efficiency and the fastest solution.

Application Development with Finite Element Method to Calculate Photogeneration Rate and Open-Circuit Voltage of Dye Sensitized Solar Cell

Amongst the several alternative resources, renewable energy source (RES) can provide continuous and clean energy. Furthermore, RESs have received a worldwide attention and an outstanding role is attributed to them. The sun energy can be exploited using light energy conversion applications such as photovoltaics. Dye Sensitized Solar Cell (DSSC) is third-generation photovoltaic device and a forwardlooking, easily producible solar cell. Nevertheless, buying a commercially available DSSC, datasheet and material information are unavailable. Thus, the purchased DSSC is a black box. The main motivation is that to develop a MatLab application which is able to determine the material information and parameters of the Dye Sensitized Solar Cell from some incoming parameters. The goal of the study is to describe the peration of the developed MatLab application which calculated the photogeneration rate in function of the thickness of the cell, the open-circuit voltage, and to illustrate its operation via an example. The photogeneration rate is solved using the numerical finite element method as a numerical procedure. In our model the Beer-Lambert law is implemented. The model takes into consideration the measured parameters of the light such as photoncount-wavelength spectrum, transmissionwavelength spectrum and irradiation intensity-wavelength spectrum. Furthermore, the open-circuit voltage is an elementary electric parameter of a solar cell.

Fatigue life prediction for Al–Zn–Mg alloy butt welded joints based on a fatigue damage model accounting for the influence of interior porosity

AbstractThis paper proposed a high‐cycle fatigue life prediction method for Al–Zn–Mg alloy welded joints considering the thermal process of welding and the effect of welding pores. First, the welding process was simulated by a numerical thermal–mechanical analysis. The residual stresses were then obtained and applied as the initial stress field of the subsequent fatigue life calculation. Second, a fatigue damage model was constructed by introducing a dimensionless quantity to equivalently describe the effect of interior pores. Further, a corresponding damage mechanics–finite element numerical method was numerically implemented by the ABAQUS platform to calculate the high‐cycle fatigue life for Al–Zn–Mg alloy welded joints. The calculated lives have good consistency with test data, which validates the feasibility and applicability of the proposed model and the calculation method. Finally, the curves of the cyclic stress versus fatigue life of Al–Zn–Mg alloy welded joints with different interior pore sizes were calculated to explore the influence law of the welding pore.

Quantitative characterization of volcanic expansion fractures based on thermodynamic coupling analysis

In recent years, volcanic reservoirs in the Bohai Sea have become the focus of oil and gas exploration and development. Volcanic activity during the Cenozoic provided favorable conditions for the development of hydrocarbon traps. These volcanics also result in difficulties during the drilling and development of oil and gas fields. Furthermore, the high-temperature magma induced thermal expansion in the surrounding rocks, which changed the local stress field and affected the fracture distribution characteristics of the surrounding strata. The complexity of the fracture distribution makes predicting lost circulation difficult and causes substantial economic losses. Therefore, it is necessary to characterize the volcanic perimeter expansion-type fractures effectively. The distribution of volcanic rocks is identified through logging and seismic data, with perimeter fracture development characteristics being analyzed. The temperature conditions of the volcanic activity were determined through core mineral analysis and thin section observation. Based on the laws of energy conservation and geomechanics, the principle of thermal coupling was applied to quantitatively predict the thermal expansion fractures caused by volcanic activity using a finite element numerical simulation method. To determine the extent of volcanic influence on lost circulation, and the development characteristics of fractures under the influence of these rocks were analyzed. The results provide an important reference for drilling and volcanic reservoir prediction in the Bohai Basin and guide for elsewhere.