Two-dimensional Finite Element Analysis Model Research Articles

Research on seismic fragility of subway station based on incremental dynamic analysis method

Seismic intensity measure is an significant parameter that affects the accuracy of structural seismic risk assessment, and plays an important role in the performance-based earthquake engineering research framework. Taking a two story, three span, and shallow buried subway station as the research object, a two-dimensional finite element analysis model of soil structure underground in a typical engineering site was established using ANSYS. Ten earthquake records were selected from PEER as input, and the structural seismic fragility analysis method based on incremental dynamic analysis (IDA) method was introduced into the subway station structure. The maximum story drift angle was used as the structural damage index, and three typical seismic intensity measures were selected, the exploration is conducted on the seismic intensity measures applicable to shallow buried subway stations and the variation pattern of seismic response of subway stations with increasing seismic amplitude. The seismic fragility curve of shallow buried subway station structures is established to obtain the failure probability of the structure at different seismic intensity levels. The analysis results indicate that for shallow buried subway stations, PGA is the most suitable seismic intensity measure, and the comparison with existing empirical fragility curves shows that the vulnerability analysis method is feasible and can quantitatively provide the failure probability of structures at different performance levels, providing reference for seismic design of underground structures.

Enhancing the Sealing Performance of Bolted Ball Joints by Gaskets: Numerical Simulation and Experiment

With the increasing utilization of bolted ball joint steel mesh structures in offshore floating platforms and deep-sea fish cages, the issue of seawater infiltrating the joints and members through the installation gaps of the bolted ball joint, leading to subsequent corrosion, has become increasingly prominent. This article presents an innovative method to improve the sealing performance of bolted ball joints. The approach involves creating sealed surfaces within the contact gaps between the sleeve and connecting components by adding circular grooves and sealing washers to both ends of the sleeve. Subsequently, a two-dimensional finite element analysis model of the bolted ball joint with the sealing structure was created using SOLIDWORKS 2021 and ANSYS Workbench 2022 R1. The study analyzes the sealing gasket’s contact pressure at various compression levels and evaluates its performance with bubble tests for air tightness. Research results show a linear relationship between the contact pressure and compression rate, achieving sealing pressures of 2.91 MPa, 4.22 MPa, and 5.95 MPa at compression levels of 8%, 11%, and 14%, respectively. Experimental testing demonstrates that the improved bolted ball joint exhibits excellent sealing performance.

Deformation of Sandy Ground Induced by Tunneling of Super-Large-Diameter Shield—Influence of Buried Depth of Tunnel and Relative Density of Sand

The mechanical properties of sandy soil depend on both the confining pressure and the state of compactness. Therefore, both the buried depth of the tunnel and the relative density of the sand are key factors that affect the ground deformation induced by the tunneling of a super-large-diameter shield. In this study, the parameters of the SANISAND constitutive model are first calibrated based on triaxial test data for Foshan silty fine sand. Then, based on the actual project, a two-dimensional finite-element analysis model is established to investigate the ground deformation induced by the tunneling of a super-large-diameter shield. The width and maximum value of the settlement trough, the volume loss ratio, and the deformation characteristics of the soil are summarized and analyzed for 13 cases. The results show that as the ratio of the buried depth to the diameter and the relative density of sand increases, the anti-disturbance ability of the sand layer to the tunnel construction increases and the volume loss ratio of the stratum reduces correspondingly. The denser the sand and the smaller the confining pressure of the soil around the tunnel, the more significant the shear-induced expansion of the sand at the tunnel haunch; this expansion partially makes up the volume loss caused by the tunnel excavation and reduces the loss ratio of the stratum at the arch crown.

Nonlinear study on the structure-soil-structure interaction of seismic response among high-rise buildings

Based on the 1–3 identical high-rise buildings with pile-raft foundation, a series of building-site two-dimensional finite element analysis models with different building spacings is established. Then, considering the nonlinear characteristics of soil and structure, the static-dynamic coupled numerical simulations are conducted to study the structure-soil-structure interaction (SSSI) under different ground motion. The results show that: 1) Adjacent high-rise buildings have the most unfavorable impact on the peak acceleration of the 1/4–1/2 height floors of the middle building, and increase the normalized response acceleration spectra value of acceleration near the second natural period of the structure; 2) Adjacent high-rise buildings have the most significant impact on the inter-story drift of the top, bottom and basement of the middle building; 3) Adjacent high-rise buildings redistribute the total horizontal shear force of the pile top of the middle building among the pile foundations, so that the peak value of the pile top shear force of each pile changes significantly, which is extremely unfavorable to the seismic safety of the structure. It should be taken seriously in the seismic design of structures. In addition, the structure spacing that results in favorable or unfavorable effects is discussed, and the reasons for the impact are analyzed.

Multi-objective Optimization of Linear Proportional Solenoid Actuator

This paper employed a multi-objective Genetic Algorithm (GA) process to optimize the structure parameters of Linear Proportional Solenoid (LPS). And designed objectives include magnitude of static push force, stability of push force with displacement in working range and push force to mass ratio. A two-dimensional finite element analysis model is presented to reduce the large calculation time generated by GA process. The optimization process result of LPS shape parameters is obtained and the optimal LPS is manufactured. Through using a high-precision measuring device in the static push force test, a comparison result between conventional shape and optimal shape shows that the proposed optimization strategy is feasible.

PCM thermal conductivity effect on mechanism of PV/PCM thermal control characteristics

ABSTRACT According to the structure of photovoltaic/phase change material (PV/PCM), the mechanism of internal heat transfer, transmission, storage, and temperature control is analyzed, and a two-dimensional finite element analysis model of PV/PCM structure is established. This study is carried out on the effect of PCM thermal conductivity on internal temperature distribution characteristics of PV/PCM and temperature control characteristics of solar cells. The results show that the increase in thermal conductivity of PCM can prolong the temperature control time of solar cell in PV/PCM system, for example, when the thermal conductivity is increased from 0.2 W/(m·K) to1.5 W/(m·K) under a thickness of 4 cm, the duration when PV/PCM solar cell temperature is controlled below 40°C and extended from 52 min to 184 min. In addition, PV/PCM experimental prototypes are designed with the LA-SA-EG composite PCM peak melting point of 46°C and thermal conductivity of 0.8 W/(m·K) and 1.1 W/(m·K), respectively. The results indicate that compared with PCM-free solar cells, the maximum temperature of PV/PCM prototype solar cells with thermal conductivity of 0.8 W/(m·K) and 1.1 W/(m·K) is reduced by 10.8°C and 4.6°C, respectively, with average output power increased by 4.1% and 2.2%, respectively, under simulated light sources. Under natural light conditions, the average output power is increased by 6.9% and 4.3%, respectively. The results provide theoretical and experimental basis for the optimization of PV/PCM design by changing the thermal conductivity of PCM.

A Performance Improvement Strategy for Solenoid Electromagnetic Actuator in Servo Proportional Valve

This study presents a simulation model, optimization strategy and the experimental validation of a solenoid electromagnetic actuator that is widely used in industry components, especially in pneumatic/hydraulic valves. In the preliminary design, a two-dimensional magnetostatic finite element analysis (FEA) model is proposed and verified by static push-force comparisons between the two-dimensional FEA model, the three-dimensional FEA model and the experimental results. Then, a static and dynamic performance improvement strategy is proposed. To optimize the static push-force of the actuator, a static multi-objective optimization strategy for actuator structure parameters was developed based on a genetic algorithm. An experimental analysis of dynamic performance was carried out to improve the dynamic response of the actuator. By using a high-precision measuring device in the static-push-force test and dynamic direct current-input-signal tests, the comparisons results between the manufactured conventional actuator and the manufactured optimal actuators showed that the proposed optimization strategy was feasible. Through the static optimization strategy, the average static push-force in the working stroke was improved by 21.8%. Moreover, through the dynamic optimization strategy, the cutoff frequency of the push force response was improved by 129.1%, 79.6% and 74.3%, respectively, at three key positions in the working stroke.

Analysis on influence of adjacent buildings on mutual seismic acceleration response

During an earthquake, the seismic response of adjacent buildings will be affected by each other, which is known as structure-soil-structure interaction (SSSI). In order to study the SSSI between neighboring buildings, the slab foundation frame structure on a typical type II site in Nanjing is used as the object. ABAQUS software is used to establish a nonlinear static-dynamic coupling two-dimensional finite element analysis model of a single building and multiple buildings with different spacing. The numerical analysis of the model shows that: Under the action of earthquakes, the increase of surrounding structures will increase its own acceleration response; when the building spacing ratio is 1/2 and 1/4, the existence of adjacent buildings will reduce its own acceleration response. When the spacing ratio is greater than or equal to 1, the impact tends to be unfavorable, and it is the most unfavorable when the spacing ratio is 2. When the spacing ratio is greater than or equal to 4, the impact of adjacent buildings on each other’s peak acceleration response can be ignored.

Above-floor tube-and-plate radiant floor model development and validation

While some building energy simulation tools include dedicated models to represent thermally massive embedded-tubes radiant floor systems, there are no models available for lightweight above-floor tube-and-plate (AFTP) systems. AFTP systems consist of a grooved wooden subfloor (or high density insulation layer), and conductive fin. This paper discusses the development of a transient AFTP radiant floor model and its implementation into ESP-r. This AFTP radiant floor model uses the general approach of the existing embedded-tube model in ESP-r and combines an analytical model of the tube with a two-dimensional finite difference model of the top layers of the floor construction. The new AFTP radiant floor model was found to compare closely with a transient two-dimensional finite element analysis model. Additionally, a full-scale transient experiment was conducted to empirically validate the model. The new model's predictions were found to be in close agreement with the measurements from this experiment.

Stress behavior of cemented fiber-reinforced composite and titanium posts in the upper central incisor according to the post length: Two-dimensional finite element analysis

Background/purposeThis study examined the stress distribution in endodontically treated maxillary central incisors restored with various lengths of either titanium or fiber-reinforced composite (FRC) post-and-core systems, using two-dimensional finite element analysis models. Materials and methodsEight models of the maxillary central incisor were formed, surrounded by cortical bone, cancellous bone, and the periodontal ligament. Two different post-and-core systems, titanium and FRC posts (D.T Light Post), were modeled. In each restorative system, four models were designed by changing the post lengths cemented to the root at 10 mm, 9 mm, 8 mm, and 7 mm. A 100-N load was applied at a 45° angle to the long axis of each model. The stress distribution levels were calculated according to the Von Mises criteria. ResultsThe titanium post showed stress concentrations toward the post when loaded, and its stress concentration shifted toward the direction of the crown with a decreasing post length. In contrast, there was no stress concentration in the FRC post when loaded and no shift of the stress concentration toward the crown with a change in the post length. ConclusionResults suggest that the possibility of fracture of the FRC post is relatively low, compared to the titanium post, even for a short post. The same criteria for installation of a metal post should not be applied to an FRC post.

고무 마운트로 이산 지지되는 플로팅 슬래브 궤도의 실모형 실내 실험에서의 정적 및 저주파 대역 동적 거동

Recently, with increasing social interests on noise and vibration induced by railway traffic, the application of floating slab track that can efficiently reduce the railway vibration is increasing. In this study, to more accurately understand the dynamic behavior of the floating slab track, a laboratory mock-up test has been performed, and the static and dynamic behaviors at frequency range near the system resonance frequency were explored. Based on the test results, the design of the floating slab track and the structural analysis model used in the design have been verified. The analytic and test results demonstrate that the dominant frequency of the floating slab track occurs at the frequencies between vertical rigid body mode natural frequency and bending mode natural frequency, and the dominant deformation mode is close to the bending mode. This suggests that in the design of the floating slab track, the bending rigidity of the slab and the boundary conditions at slab joints and slab ends should be taken into consideration. Also, the analytic results by the two-dimensional finite element analysis model using Kelvin-Voigt model, such as static and dynamic deflections and force transmissibility, are found in good agreement with the test results, and thus the model used in this study has shown the reliability suitable to be utilized in the design of the floating slab track.

Topology Optimization for a Micro/Nano Compliant Grip and Move with Parallel Movement Tips Using Multi-Objective Compliance

Abstract The past few years have witnessed an increasing maturity of the micro- and nano-electro-mechanical systems (Mems/Nems) industry and a rapid introduction of new products addressing applications ranging from biochemical analysis to fiber-optic telecommunications. The assembly of micro-devices involves handling of parts that are extremely very small. A microgripper compliant mechanism is one of the key elements in micro-robotics and micro-assembly technologies for handling and manipulating micro- objects without damage. This paper presents the design of compliant grip and move manipulators with parallel movement tips. The integration of both, gripping and moving manipulators, with parallel movement tips is accomplished by the use of compliant mechanisms, which generate paths that are symmetric. These mechanisms can grip an object and convey it from one point to another with parallel movement. The structural topology optimization approach is applied in order to find the optimal material distribution in the proposed domain for compliant mechanisms. The objective of the optimization problem is to maximize the structural stiffness within the limit of prescribed design volume. A two-dimensional finite element analysis model using Ansys is constructed for the proposed design domain. Three optimal configurations of two-dimensional compliant mechanism, which can realize a micro grip and move with parallel movement tips for a wide range of micro- and nano-objects, are demonstrated.

Peeling experiments of ductile thin films along ceramic substrates – Critical assessment of analytical models

Two types of peeling experiments are performed in the present research. One is for the Al film/Al 2O 3 substrate system with an adhesive layer between the film and the substrate. The other one is for the Cu film/Al 2O 3 substrate system without adhesive layer between the film and the substrate, and the Cu films are electroplated onto the Al 2O 3 substrates. For the case with adhesive layer, two kinds of adhesives are selected, which are all the mixtures of epoxy and polyimide with mass ratios 1:1.5 and 1:1, respectively. The relationships between energy release rate, the film thickness and the adhesive layer thickness are measured during the steady-state peeling process. The effects of the adhesive layer on the energy release rate are analyzed. Using the experimental results, several analytical criteria for the steady-state peeling based on the bending model and on the two-dimensional finite element analysis model are critically assessed. Through assessment of analytical models, we find that the cohesive zone criterion based on the beam bend model is suitable for a weak interface strength case and it describes a macroscale fracture process zone case, while the two-dimensional finite element model is effective to both the strong interface and weak interface, and it describes a small-scale fracture process zone case.

Modeling nonlinear peeling of ductile thin films––critical assessment of analytical bending models using FE simulations

Three analytical double-parameter criteria based on a bending model and a two-dimensional finite element analysis model are presented for the modeling of ductile thin film undergoing a nonlinear peeling process. The bending model is based on different governing parameters: (1) the interfacial fracture toughness and the separation strength, (2) the interfacial fracture toughness and the crack tip slope angle, and (3) the interfacial fracture toughness and the critical Mises effective strain of the delaminated thin film at the crack tip. Thin film nonlinear peeling under steady-state condition is solved with the different governing parameters. In addition, the peeling test problem is simulated by using the elastic–plastic finite element analysis model. A critical assessment of the three analytical bending models is made by comparison of the bending model solutions with the finite element analysis model solutions. Furthermore, through analyses and comparisons for solutions based on both the bending model and the finite element analysis model, some connections between the bending model and the finite element analysis model are developed. Moreover, in the present research, the effect of different selections for cohesive zone shape on the ductile film peeling solutions is discussed.

Thermal peeling stress analysis of thin-film high-TC superconductors

Abstract Thermal peeling stress between a thin film and the substrate is caused by the mismatch of thermal expansion coefficients while the film and substrate undergo a temperature change. The thermal peeling stress resulting from the temperature decrease from ambient to operating conditions (cryogenic temperatures) between a thin-film high-temperature superconductor and its substrate is calculated using finite element analysis (FEA). The superconductor thin film is idealized as a long bridge on a large substrate. A two-dimensional FEA model is applied to calculate the tensile (peeling) stress at the thin film/substrate interface. Results are obtained for different geometries and temperature conditions, and these results are compared with analytical predictions. A stress singularity is found at the very edge of the thin film which is not predicted by the analytical prediction. The peeling stress can be very high due to this stress singularity, even if the temperature change is not large. The stress singularity area depends on the local geometry of the edge, suggesting that refining the geometry of the thin-film HTS device is important.