General Finite Element Analysis Research Articles

Study on Bearing Mechanism of Steel Screw Pile

In order to study the bearing mechanism of a steel screw pile (SSP), a 3D-FEM of “SSP-stratum” was established based on the large-scale general finite element analysis platform ABAQUS. Secondly, the real friction coefficient between pile and soil was determined by comparing it with the field bearing test data of screw piles. Finally, the bearing mechanism and failure criterion of the SSP was revealed. The research showed that the pile-soil friction coefficient was about 0.6 under the condition of this stratum, and the screw pile was in the elastic working stage under the conditions of compression and tension load, which had a large bearing reserve. The magnitude of Young’s modulus was inversely correlated with the settlement value and the extreme value of principal stress. The increase in the Young’s modulus of the stratum was helpful in improving the bearing capacity of the screw pile. The compressive capacity of circular steel tube + screw pile (CST + SP) was about 2 times higher than CST, and the compressive capacity of circular steel tube + large blade + screw pile (CST + LB + SP) was about 2.4 times higher than CST. The tensile capacity of CST + SP was about 3.4 times higher than CST, and the tensile capacity of CST + LB + SP was about 4.9 times higher than CST. The arrangement of large blades better bore the load of the screw part and optimized the stress distribution of the structure. Based on the mechanical analysis in the vertical direction, the bearing mechanism of the SSP under compression and tension conditions was elaborated. The bearing failure criterion of the SSP was summarized from the aspects of mechanics and displacement. The bearing design of the SSP should meet the control of mechanics and deformation at the same time. The research work could provide a useful reference for the design and construction of SSPs.

Modeling of the accurate application of the Kernel Efficiency Method in the proportioning process of shield tunnel construction

Abstract The existing control strategies for subway construction struggle to address the challenges posed by the impact of large-diameter shield-driven underpass subway tunnels on soil settlement. In this paper, based on the mechanism of ground settlement of the shield tunnel under the KNX method, the influence of the underpass tunnel on the existing tunnel and its surrounding soil stress-strain characteristics is calculated by the Peck superposition method. The KNX method is optimized by optimizing the ratio of KNX slurry and the grouting pressure to control the existing tunnel and the ground settlement. The geotechnical general finite element analysis software is being introduced to conduct numerical simulation and engineering application experiments to verify its effectiveness. The results show that when the bonding force of the grouting material is 350Pa-s, the maximum value of the variation is 3.91mm, and the mobility is more suitable, which can effectively fill the void of the shield machine and reduce the settlement of the foundation. When the grouting pressure is 280kN/m2, the maximum contraction of the tunnel is 6.25mm, which can ensure the safety of the existing tunnel on the basis of the tunnel so that the actual settlement of the soil in the tunnel is minimized. Comprehensively, the optimization of the ratio of the KNP method in the control of the deformation characteristics of the soil and structures under the shield tunnel has effectiveness and can effectively provide theoretical and technical guidance for the construction of subway tunnels under the large-diameter shield under the subway.

Progressive Failure Analysis of Composite Overwrapped Pressure Vessel

Stress and progressive failure analysis (First Ply Failure to Last Ply Failure) of a composite overwrapped pressure vessel (COPV) with an aluminum liner using the finite element method (FEM) in general and commercial finite element analysis (FEA) software ANSYS in particular is presented in this paper. Ply failure prediction is based on failure criteria implemented in ANSYS software. The first-ply failure (FPF) does not necessarily imply the total failure of a laminate. After FPF, the laminate stiffness is reduced consistent with identified ply failure mode. The strength of the composite laminate is evaluated again to see if it could carry additional load. This ply-by-ply analysis progresses, until the ultimate strength is reached. In the present study the methodology is validated using benchmarks and applied to a filament wound fibre reinforced plastic composite pressure vessel with an aluminum liner. Significant results are presented and critically assessed. Directions for further work in this field are identified.

Numerical study on the influence of geometric parameters on mechanical properties of Tapered Head Grouted Sleeve joints

In order to ensure the effectiveness of the Tapered Head Grouted Sleeve (THS) joints and reduce its impact on prefabricated components, three-dimensional numerical analysis models were established based on the large-scale general finite element analysis software ABAQUS. On the basis of verifying the validity of the model, numerical uniaxial tensile tests were carried out on THS joints of different sizes, this research mainly considered the influences of the diameter and embedded length of the bar and the diameter, angle and length of the sleeve on the connection performance and strain characteristics of the THS joints, and a theoretical model for the tensile strength of THS joints was proposed. In addition, based on the numerical tensile test results of THS joints with different parameters, the concept of diameter-angle ratio (ζ) suitable for THS was established, and a simple calculation method was proposed to predict whether the connection of THS joint is effective. The results illustrated that: THS joint embedded length should be at least 6 times the diameter of the bar; Increasing the embedded length or reducing the sleeve diameter are beneficial to reduce the tensile strain of the sleeve; The calculated results of the theoretical model were in good agreement with the numerical results; When the minimum embedding length is satisfied, the range of diameter-angle ratio that the THS joint need to meet is 0.52≤ζd≤0.63.

Fluid–Structure Interaction Analysis and Verification Test for Soil Penetration to Determine the Burial Depth of Subsea HVDC Cable

Recently, there have been frequent reports of subsea cable breakage accidents caused by the drop of an anchor pile for aquaculture works involving subsea cables for high-voltage direct current (HVDC) transmission embedded in the southwest sea of Korea. To determine the burial depth that can ensure the safety of subsea HVDC cables embedded under the seabed from the drop of anchor files, the soil penetration characteristics of anchor piles should be reasonably estimated. In the present study, the penetration characteristics of anchor piles into the soil under which subsea HVDC cables are embedded were evaluated using numerical simulations and field verification tests. The numerical simulation for the soil penetration phenomena of anchor piles was carried out using the fluid–structure interaction analysis method using the general purpose nonlinear finite element analysis code based on explicit time integration. Regarding the soil into which anchor piles penetrate, three types of soil—a clay layer, a sand layer, and a clay–sand mixed layer—were considered, which are the representative soil types in the southwest sea of Korea, where many subsea HVDC cables have been embedded. The result of fluid–structure interaction analysis showed that the maximum penetration into the clay layer was higher than that into the sand layer and the clay–sand mixed layer by 86.3% and 36.4% or more, respectively. The error rates of the field verification test and the fluid–structure interaction analysis were found to be 9.8%, 2.4%, and 2.4% in the clay layer, the sand layer, and the clay–sand mixed layer, respectively, which were found to be reasonable levels when considering that it was the numerical simulation for the soil penetration of an anchor pile resulting from drop impacts. The penetration depths of anchor piles were found to be the deepest in the clay layer, showing values of 3.9 to 4.1 m, and those in the sand layer were the shallowest, showing values of 1.9 to 2.1 m.

A general mathematical modeling and finite element analysis of a strain wave gear possessing a double-circular-arc-with-a-common-tangent profile

In this study, the characteristics of a strain wave gear (SWG) with a double-circular-arc with a common tangent (DCACT) profile were simulated using two-dimensional (2D) and three-dimensional (3D) finite element analysis (FEA). First, theoretically generated tooth profiles for the flexible spline (FS) and circular spline (CS) of an SWG were developed according to the theory of gearing. An automated mesh-generating computer program was developed in Visual C++ to establish 2D and 3D finite element models of the SWG based on its derived geometry. An FEA was then performed to explore the meshing characteristics, including the stress distribution, torsional angle, torsional stiffness, and number of engaged teeth, of the SWG. Continuous meshing of multiple tooth pairs between the FS and CS from the 2D FEA verified the conjugation of tooth profiles. The coning effect on the FS during assembly of the SWG was also predicted and discussed from the 3D FEA results. The 3D FEA produced more accurate and practical results than the 2D FEA did. Additionally, 3D FEAs of a modified (with longitudinal crowning) and unmodified (without longitudinal crowning) FS were performed and compared. Finally, a 3D FEA of a modified FS was successfully conducted to predict cyclic contact stress, root stress, and transmission error.

Parameters Identification of Rubber-like Hyperelastic Material Based on General Regression Neural Network.

In this study, we present a systematic scheme to identify the material parameters in constitutive model of hyperelastic materials such as rubber. This approach is proposed based on the combined use of general regression neural network, experimental data and finite element analysis. In detail, the finite element analysis is carried out to provide the learning samples of GRNN model, while the results observed from the uniaxial tensile test is set as the target value of GRNN model. A problem involving parameters identification of silicone rubber material is described for validation. The results show that the proposed GRNN-based approach has the characteristics of high universality and good precision, and can be extended to parameters identification of complex rubber-like hyperelastic material constitutive.

Efficient form-finding algorithm for freeform grid structures based on inverse hanging method

Grid structures and branching columns have been widely adopted due to their high structural efficiency and novel appearance. High structural efficiency must be achieved through a strict form-finding analysis. Existing algorithms are mainly applicable for grid structures or branching columns only. However, the form-finding of upper grid structures and the lower branching columns are mutually affected. A form-finding algorithm is needed for grid structures supported by branching columns. In the present work, an efficient form-finding algorithm suitable for grid structures is initially proposed, and the feasibility of this algorithm is verified through three examples. Then, the form-finding algorithm for grid structures is integrated with the form-finding algorithm of branching columns. Results indicated that the proposed algorithm can be used for form-finding analysis of various grid structures supported by branching columns. This work was conducted using a general finite element analysis program and can be easily mastered by engineering designers while avoiding tedious programming.

A novel assumed-strain finite element for detecting the elastic behavior of wall-like structures

It is aimed to propose a new triangular plane finite element to improve the accuracy and reduce the computational effort for analysis of plane structures. The suggested element is formulated by assuming an incomplete second-order strain field. It leads to an element free from shear parasitic error with lower sensitivity to the mesh distortion. Satisfying both equilibrium and compatibility equations in the strain field level results in 12 independent strain states. Accordingly, the suggested element has 12 degrees of freedom, which are allocated to six nodes. Although the suggested element has the geometry and number of degrees of freedom same as the well-known linear strain triangular element, but its accuracy and efficiency are much better than many of the available high-performance membrane elements. The selected geometry provides the opportunity to simply include the presented element in the general finite element analysis software. After evaluation of the element performance using basic benchmark problems, to demonstrate the efficiency of the proposed formulation in comparison with widely used finite elements, different shear and retaining wall structures are analyzed by the developed element. The attained results for even coarse meshes prove higher accuracy and efficiency of the developed element in computation of displacements and stresses. Another advantage of the proposed element in comparison with the other available robust finite elements is its simple and straightforward formulation.

A DBN-PSOSA hybrid response surface method for bridge reliability

When solving bridge reliability problems, the traditional response surface method has a highly nonlinear implicit function, which results in a low fitting accuracy and difficulty in meeting the requirements. Therefore, the dynamic Bayesian network (DBN), which is suitable for solving a multi-state unit or system uncertainty problems, is selected to construct the response surface of the implicit function. In this study, the DBN model is combined with the particle swarm optimisation based on simulated annealing (PSOSA) algorithm to improve the optimisation efficiency of model parameters and allow the constructed implicit function to simulate the structure limit state function. The DBN-PSOSA hybrid response surface analysis method is proposed for bridge failure probability calculations. A numerical example is given to demonstrate the effectiveness of the proposed method, and the reliability of an actual bridge project is analysed. The results indicate that this method has a higher calculation accuracy and efficiency compared to the traditional response surface method, and is easy to combine with the existing general finite element analysis software to achieve the rapid analysis of bridge structure reliability.

Finite Element Analysis on Hysteretic Behavior of H-shaped Columns of Thin-Walled Sections of 690 MPa High Strength Steel

High strength steel is widely used in engineering, especially in light steel structures. However, due to the material properties of high strength steel, its seismic performance has attracted wide attention. To study the hysteretic behavior of H-shaped members of thin-walled sections of Q690 high strength steel, a finite element model was built up by using the general finite element analysis software ABAQUS. Based on the finite element model, an extensive parametric analysis of H-shaped members of thin-walled sections of Q690 high strength steel was carried out. The results showed that the limiting flange width-thickness ratio and web height-thickness ratio for H-shaped members of Q690 high strength steel were recommended to be 11 and 65, respectively, in actual engineering. Also, an increase in web height-thickness ratio and axial compression ratio could lead to a significant decrease in the ductility of H-shaped members of thin-walled sections of Q690 high strength steel. The thinner and more flexible the section is, the larger the axial compression ratio is, further reducing the energy dissipation ability of the members.

Seismic Performance Analysis of Reinforced Concrete Frame Structures Based on Computational Mechanics

In order to study the degradation law and seismic performance of reinforced concrete frame structure with the extension of service time under normal service environment, the multi-scale modeling of corroded reinforced concrete frame is carried out by using the general finite element analysis software ABAQUS. The correctness of the multi-scale modeling method is verified by the experimental data of corroded reinforced concrete members and single frame. The pushover analysis and elastic-plastic time history analysis of a four story reinforced concrete frame structure are carried out by using a multi-scale model. Then the seismic response and damage of RC frame structures with different service time are compared. The experimental results show that the established seismic performance model of reinforced concrete frame structure is more practical in practical application and can meet the research requirements.

Study on Mechanical Properties of Concrete-Filled Aluminium Alloy Tube Column under Lateral Impact

Concrete-Filled Aluminium Alloy Tube (CFAAT) column may be damaged by lateral impact. Based on general finite element analysis software, the dynamic analysis and performance of lateral impact of CFAAT columns with different tube wall thickness are studied in this paper. The results show that when the outer diameter of the columns is constant, the impact resistance of the columns can be improved by increasing the thickness of the aluminium alloy (Al alloy) tube, and the reinforcement of the core concrete constraint by increasing the strength and thickness of the Al alloy tube is the main reason for the enhancement of the impact resistance.

Stray Load Loss Calculation for Induction Motor by Combination of General Airgap Field Modulation Theory and 2D FEA

The accurate calculation of stray load loss has an important contribution to increasing motor efficiency. The stray load loss can be regarded as the difference of the total iron losses and harmonic rotor cage losses between the no load and load conditions. A method combining the general airgap field modulation theory (GAFMT) and 2D finite element analysis (FEA) is proposed for calculating the stray load loss of the squirrel cage induction motor (SCIM). Firstly, the amplitudes and rotation speeds of the main space harmonics of the airgap magnetic flux density are calculated based on the GAFMT. And the relationships between these space harmonics and stray load loss are analyzed. Secondly, these space harmonics are synthesized by the equivalent current layers in the airgap and then are substituted into the 2D FEA models to calculate the losses. At last, the stray load loss calculated by the proposed method is compared with that obtained by practical motor tests.

Study on the performance of a restored concrete bridge after ship impact in China

The WanJiang Bridge in China was damaged by an oil tanker at 5.28 p.m. on 5 August 2006, and three supporting frames near the mid-span of the bridge, 5# pier, were severely damaged. Some concrete members fell into the river, causing significant changes in the structural behaviour of the bridge. Thereafter, the administration department has done some emergency detection, strengthening design and strengthening construction to the bridge. A field load test and simulation of the bridge using the large-scale general finite-element analysis software Midas were performed. According to the comparative analysis and model validation of the field load test and the results of simulation analysis, the bridge bearing capacity after strengthening is evaluated, and a maintenance proposal for the bridge is given. The results of the research show that the results of static and dynamic load tests agree well with the theoretical value; the latter verifies the correctness of the theoretical analysis. Based on the field load test, comparative analysis and computational evaluation, the strengthening effect on the WanJiang Bridge is evaluated from the aspects of static performance and dynamic performance.

Effect of change of cross section and Frequency Analysis of Anti-Roll Bar Using FEA

Anti-roll bars are the suspension system component in automobiles that are used to control the body roll effect. They have a strong impact on the handling functions of the engine. The design effects of the anti-roll bar are normal in different vehicles and the study is mandatory for each design change. Finite Element Analysis (FEA) is used for an accurate study of the anti-roll bar style. The finite element analysis is carried out in ANSYS. The paper comprises of pre-processing, evaluating, post-processing, and using the work bench to interpret the FEA results. Be that as it may, because of a high number of rehashed plans looks at, deciphering time and cost issues related with the utilization of general FEA bundle projects may create critical inconveniences in utilizing these bundle projects to perform against move bar structure examination. Vibration characteristics such as typical set vibration levels and frequency are varied within the automotive environment. Even if an automobile is driven, the random excitations from road inputs and intermittent vibrations from engine firing are felt by its components and structures. It can sometimes cause problems with reliability if the construction of the components is often not completely evaluated.

LAGRANGIAN DESCRIPTION AND FINITE ELEMENT ANALYSIS OF RELUCTANCE ACCELERATOR CIRCUIT MODEL

Lagrangian description of electrical circuit model of a reluctance type accelerator system is introduced. The effectiveness of the general purpose magnetostatic finite element analysis (FEA) tools on the introduced model is demonstrated. Electrical equivalent circuit model of the system lays out many properties of the system in terms of voltage, current, power or energy distributions of electrical components, and also electrical equivalent of the mechanical components, in an easily perceivable form. These type of actuators are simple mechanisms when they are in steady state. However, when they are in transient, their dynamics may become very complex. The aim of the study is to show how this approach allows many researchers without the full electromagnetic background, to model and understand the dynamics of the reluctance type linear or rotary motor or actuators whether they are saturated or not. To exhibit the validity of the proposed model and solution of dynamic behaviors with FEA, it is verified on a basic capacitor discharge type driver circuit including the electromagnetic accelerator coil and projectile.

Heat pipe failure accident analysis in megawatt heat pipe cooled reactor

The heat pipe cooled reactor is an advanced reactor design which is nearly solid-state with an array of in-core heat pipes for passive heat transfer. The local heat pipe failure probability is certainly high over the reactor lifetime. Therefore, the reactor design must include consideration of heat pipe failure accidents which needs to be explored in-depth. The Monte Carlo neutron transport code RMC was used with the general finite element analysis software ANSYS Mechanical to analyze the thermal/mechanical characteristics of a megawatt heat pipe cooled reactor for both normal and heat pipe failure conditions. The simulations were verified against a previous study with the predicted temperature distributions being consistent with each other with an absolute error of less than 3 K. Further analyses show that a 2-D model simulation can also well represent the 3-D model for heat pipe failure accident analyses. Sterbentz et al. (2017) simplified the heat pipe model with a constant temperature boundary condition along the evaporator wall of 950.15 K regardless of the heat load or heat pipe operating temperature. Therefore, a heat pipe subroutine was added to the codes to predict the heat pipe temperatures during a heat pipe failure accident. The results show that the heat pipe failure will cause larger temperature rises and stress concentrations. The heat pipe wall temperatures in the core differ from each other with the differences between the heat pipe loads during normal heat pipe operation and with failures reflecting the local effect of the heat pipe failures. The operating conditions far from the failure area are little affected (<20 K temperature change) by a single heat pipe failure. The effects of the heat pipe failure on the reactor core reactivity and local power distribution were also analyzed with a reactivity change of less than 5 pcm and a local power change of less than 0.1%. Therefore, the heat pipe failure can be analyzed in steady-state simulations with unchanged power distributions.

The strong coupled form-finding and optimization algorithm for optimization of reticulated structures

Reticulated shell structures are commonly adopted because of their long-span feature and novel appearance. These structures generally comprise slender beam members, which may cause the buckling of entire structures. A shape-finding method is proposed in this study to eliminate the bending moment while optimizing the member buckling capacity of reticulated shell structures. The proposed method (the strong coupling form-finding and optimization algorithm) can be utilized to optimize the geometrical length of each component. The effective length factor, sectional area, and moment of inertia can be accurately considered in the optimization analysis. Member length can be optimized according to the axial force and geometrical parameter. This study can systematically be adopted in the design, analysis, and optimization of reticulated shell structures. This work was conducted using a general finite element analysis program and can be easily mastered by engineering designers while avoiding tedious programming.

Influence of wear on hot banding migration of sealing ring using FEM

Hot banding is a typical thermoelastic instability phenomenon that occurs on the sealing surface of the sealing ring in a transmission. The presence of hot banding on sealing contact surfaces causes local wear. The wear of a sealing ring results in the loss of supply pressure and ultimately causes transmission failure. Local wear and hot banding migration also affect each other. This paper has discussed the influence of the wear of the sealing interface on hot banding migration using the general finite element method. A wear simulation procedure, based on Archard's wear law, was used to calculate the wear of the sealing ring, and the thermoelastic effects were also included in the simulation model. An iterative cyclic updating method was performed using the general finite element analysis software. The results of the simulation showed how wear influenced the migration of the hot banding. The worn sealing surfaces lead to more complex migration states of the hot banding, including division and combination of the hot banding. The proposed simulation method and the procedure that was used are suitable for trend analysis of seal design.