Field Finite Element Analysis Research Articles

High-Accuracy and Fast Calculation Framework for Berthing Collision Force of Docks Based on Surrogate Models

The accurate prediction of the collision force magnitude resulting from ship berthing on docks is crucial for the rationality and safety of dock structural design. This paper presents a novel framework for the calculation of berthing collision force for ships (CBCF), which integrates field data, finite element models, and surrogate models. Based on field data and finite element analysis, the framework constructs and compares four surrogate models with low sample requirements, ultimately selecting the optimal surrogate model for predicting collision force. Furthermore, a sensitivity analysis of the parameters is conducted based on the selected model, followed by a comparison with the various methods used for collision force prediction. The results illustrate the effectiveness of the proposed framework in replacing finite element models for the rapid and accurate prediction of collision force. Comparison with existing methods also underscores the advantages of the proposed framework, including low sample requirements, high calculation accuracy, and exceptional efficiency. In summary, this study not only introduces a novel and precise surrogate model framework for the swift prediction of berthing collision force, but it also offers valuable insights into the prevention of ship collision with wharf accidents and facilitates the rational and safe design of wharf structures.

Design and damping performance analysis of a multistage meandering hybrid valved magnetorheological damper

Abstract The current valved magnetorheological damper has a low space utilization of the piston head, which results in insufficient output damping force, and this paper proposed a multistage meandering hybrid valved magnetorheological damper. The three-dimensional structure of the damper is established and its mathematical model is derived. The electromagnetic field finite element analysis was used to simulate the damper structure, and a comparison was made between the results of traditional annular valve structures and those of multistage meandering hybrid valve. The damping performance of a multistage meandering hybrid valved damper was experimentally studied. The results indicate that the maximum output damping force of the multistage meandering hybrid valved structure is increased by 62.2% over the traditional annular valved structure at a current of 2.4 A and a coil turn count of 350 turns. The structure can effectively utilize the piston head space and improve the output damping force of the damper. The output damping force of the damper reaches 486.4N and the adjustable coefficient K reaches 8.6. The numerical simulation results are the same as the actual experimental results.

Investigation of Electro-Thermo-Mechanical Degradation and Crack Propagation of Wire Bonds in Power Modules Using Integrated Phase Field Modelling and Finite Element Analysis

Investigation of Electro-Thermo-Mechanical Degradation and Crack Propagation of Wire Bonds in Power Modules Using Integrated Phase Field Modelling and Finite Element Analysis

The Efficiency Improvement of Track-Type Wireless Power Transmission Systems through Electromagnetic Finite Element Analysis

The original system, designed as a combination structure of a linear machine and a wireless power transmission transformer, was designed to overcome the limitations of the wired power supply method used for working robots and transportation equipment in existing smart factories, and improvements in magnetic coupling and power transfer efficiency are needed. In this work, we study the efficiency improvement of a system that can supply wireless power to track-type transportation equipment. For this purpose, electromagnetic properties such as magnetic equivalent resistance, inductance, magnetic coupling rate, and core loss are analyzed using the finite element method. In addition, the results of magnetic field finite element analysis are applied in electrical equivalent circuit modeling to analyze the voltage transfer ratio and input/output characteristics of a CLLC resonant converter designed for wireless power transmission. The efficiency improvements of the proposed model are verified through a comparison of experimental and simulation results after fabricating a prototype. From the results of this study, a more optimized wireless power transmission system design based on the analysis results from an electromagnetic perspective can be realized to improve the efficiency of wireless power transmission.

Flexural behavior of the hollow slab girders strengthened with ultra-high performance concrete: Field full-scale experiment and analysis

Due to high strength and well durability, ultra-high performance concrete (UHPC) can be designed to strengthen damage hollow slab girder. The main objective of this study is to evaluate reinforcement feasibility of compression zone of hollow slab girder via field full-scale experiments and finite element (FE) analysis. To this end, UHPC layer was firstly proposed to reinforce top plate of damaged hollow slab girder. Then, four-point bending tests were conducted to investigate flexural behavior of hollow slab girder with/without UHPC layer. FE models were developed to simulate bending failure process of hollow slab girders. The deflection, crack propagation and stress distribution of hollow slab girders were analyzed as well as failure modes. The results show that UHPC layers can significantly improve flexural stiffness of hollow slab girder, and it results in an increase of 11.5% in cracking load and 23.7% in ultimate load, respectively. Moreover, reinforced girder exhibits well ductility and relatively high flexural bearing capacity. Furthermore, the parameter analyses were performed to investigate the effects of the thickness of UHPC layer and prestress on flexural behavior of reinforced girder. The results show that the prestress significantly affects the ductility and cracking load. Whereas, it seems to be independence of ultimate load. Finally, theoretical analysis was performed to obtain calculation formulas, which determine cracking and ultimate loads of reinforced hollow slab girder. Overall, this study has verified effectiveness of proposed reinforcement method in improving stiffness and flexural bearing capacity of hollow slab girder.

Inverse design of polymer alloys using deep learning based on self-consistent field analysis and finite element analysis

In this study, a framework that deals with the inverse design of material structures based on macroscopic properties using deep learning models is proposed. For the framework, “polymer alloy’s phase separation structures” as material structures and “stresses” as macroscopic properties are considered. The results of self-consistent field analysis are used as structure data, in particular, the analysis result of two-dimensional phase separation structures of a diblock copolymer melt in the equilibrium state. For the stress data, the results of finite element analysis are used, in particular, the analysis results of average stresses over the system under the small-enforced-displacement condition. This framework consists of two deep learning models—one aimed at generating phase separation structures, and the other at predicting properties from structures. For the second model, we incorporate a convolutional neural network. By implementing a random search toward a model that combines these two deep learning models, we constructed the framework for the inverse design of phase separation structures that possess desired macroscopic properties. This framework is demonstrated to be able to suggest phase separation structures that realize desired stresses that are input to the framework through examples. The innovation of the method is the development of framework to propose the optimal structure of polymer alloys by using machine learning. The main novelties of this method are the construction of generative adversarial network that reproduces the phase-separation structure of polymer alloy specified by label information, realization of inverse analysis based on mechanical properties, and the simultaneous optimization of multiple mechanical properties.

Introduction of a recurrent neural network constitutive description within an implicit gradient enhanced damage framework

The contribution at hand presents a method for the application of Recurrent neural network based constitutive models within a coupled field Finite Element Analysis. Thereby, an additional scalar field is coupled to the displacement field and evolved by a scalar variable at the integration points. By employing implicit gradient enhancement as regularization framework, the representation of softening material behavior is possible without the generation of localization phenomena. The feasibility of this approach is shown for an anisotropic constitutive description based on the microplane model, by employing a self-adversarial training scheme for enhanced robustness which was proposed to work for arbitrary inelastic materials. Its capabilities and limitations during application in Finite Element Analysis are evaluated and discussed for two numerical simulations.

Multiobjective Optimization and Multiphysics Design of a 5 MW High-Speed IPMSM Used in FESS Based on NSGA-II

The flywheel energy storage system (FESS) has high-power density and fast response speed, hence it is widely used as a pulse power supply. For the high-speed permanent magnet synchronous machine (HSPMSM) used in high-power FESS, there are two technical problems that need to be solved, including huge centrifugal forces of the rotor at a high-speed operation region and large phase currents at a low-speed operation region. In this paper, a 5 MW high-speed interior PMSM (HSIPMSM) is designed for FESS. The design goal of this electric machine is to reduce the maximum phase current at the lowest speed as much as possible while ensuring the rotor mechanical strength. Based on the response surface (RS) model and non-dominated sorting genetic algorithm II (NSGA-II), the multiobjective design of the HSIPMSM is accomplished using 29 groups of multiphysical field finite element analysis (FEA) sampling experiments. The computational cost is effectively reduced. In addition, the constant power optimal trajectory and control switching speed of the HSIPMSM are analyzed and discussed, and the reason that the constant power flux weakening region of the designed HSIPMSM is not wide and the maximum torque per ampere (MTPA) mode is adopted at a low-speed operation region is further illustrated.

Field Investigation and Finite Element Analysis of Landslide-Triggering Factors of a Cut Slope Composed of Granite Residual Soil: A Case Study of Chongtou Town, Lishui City, China

Landslides caused by excavations and precipitation events are widespread types of slope failures in southwest Zhejiang, China, in areas with granite residual soil. Investigations of the effect of high precipitation on the hydrological response, stability, and evolutionary mechanism of cut slopes in granite soil areas are lacking. The characteristics of historical landslides in Chongtou Town in southwestern Zhejiang were summarized, and a typical slope was selected for analysis. The hydraulic and mechanical properties of the residual soil and fully weathered granite were tested, and the surface displacements on the slope were monitored. Geo-studio was utilized to establish a coupled seepage-deformation model to validate the numerical method and investigate the landslide-triggering factors of the cut slope. The results showed nearly all historical landslides in Chongtou Town were triggered by precipitation events, and the slide bodies consisted of residual soil and fully weathered granite with similar geotechnical properties. The simulated and measured horizontal displacements were in good agreement, indicating the reliability of the established model and parameters. The stability coefficient decreased with an increase in the gradient or height of the cut slope. The critical height values were 5.3 m, 5.5 m, 5.7 m, 6.0 m, and 6.3 m at slopes of 60°, 65°, 70°, 75°, and 80°, respectively. Long-term torrential rain and short-term high-intensity precipitation events are likely to trigger landslides when the precipitation event lasts longer than 26 h and 78 h, respectively. The landslide formation includes four stages: slope evolution, formation of unloading zone at slope foot, migration and loss of soil particles, and instability of the cut slope. The findings can be used to prevent and manage landslides on cut slopes in areas with granite residual soil.

Static Response of Self-anchored Suspension Bridge under Vehicle Load Considering Time-varying Effects

In order to study the structural state of the bridge under the influence of time-varying effect, the response of the concrete self-anchored suspension bridge under vehicle load and temperature load during the 30-year operation period is studied, through field load test and finite element analysis based on ANSYS refined spatial solid model. The results show that with the increase of the service life of the bridge, the bottom plate of the box chamber of the main girder gradually tends to be tensioned in the longitudinal direction of the bridge, and the horizontal preload stress of the main girder gradually loses when the bridge is completed; The transverse bridge stress at the junction of the outermost bottom of the box chamber and the web tends to be tensile, while the transverse bridge stress at the measuring point of the inner bottom plate gradually increases. The change value of the cable force of the hanger is obviously affected by the restraint mode of the support. Affected by the main tower support, the cable force of the hanger adjacent to the main tower decreases greatly. During the operation of the bridge, the working conditions of the mid span and east span hangers shall be monitored.

Effect of the braking parameter on disc brake squeal of a railway vehicle

In order to study the generation mechanism of railway disc brake squeal and its influencing factors, a field test and a finite element analysis of disc brake squeal are carried out in the present paper. In the field test, the disc brake squeal of a railway brake unit for several different brake conditions is measured, the occurrence law of railway disc brake squeal is obtained. Test results show that the disc brake squeal has a coherent relationship with the brake pressure and the initial braking speed. The occurrence propensity of brake squeal depends on the variation of braking air pressure against time, especially the stepwise increase of brake pressure is the main cause of brake squeal. At the same time, the initial braking speed also has an effect on the occurrence of brake squeal. A full-size prediction model of brake squeal is established, which included disc, pad, bracket and two levers. The transient dynamic analysis method is used to study friction self-excited vibration characteristics of disc brake systems. The field test and finite element analysis show the disc brake finite element prediction model can correctly predict the frequency of brake noise. Finite element results show that brake pressure is the most critical factor causing brake noise. The increase of braking pressure will directly lead to the disc brake system to become more unstable. At the same time, the step growth of brake pressure also greatly increases the possibility of brake squeal. A large initial braking speed will intensify the friction vibration, and increase the frictional contact pressure.

Finite Element Analysis of Damage of Cylindrical Roller Bearing of Main Shaft of Shot Blasting Machine

The main shaft of shot blasting machine mainly uses cylindrical roller bearing as the supporting part. The influence of stress, strain and temperature on bearing damage was studied by thermal structural coupling analysis of the bearing through finite element simulation. The causes and main damage forms of bearing surface were verified by super depth of field observation and finite element analysis. It is found that there exists pyramidal strain in the contact area between inner and outer raceway and roller, and its distribution form is continuous point distribution. The stress concentration is mainly distributed in the contact area between the roller face and the retaining edge, and the roller temperature is more concentrated in the area near the end face. The maximum length and depth of spalling pit on racetrack surface were 572.2μm and 14.15μm respectively. The maximum width and depth of the scratches on the roller surface are 386.7μm and 10.7μm, and the damage degree of the roller surface is not uniform. The thermo-structural coupling analysis is used to simulate the running state of bearings, which is of guiding significance to analyze the failure forms of bearings and improve the service life of bearings.

Study on the structural design and performance of magnetorheological (MR) valve with hybrid supply magnetic source and double annular channels

Valve plays an important role in achieving precise position control for the hydraulic lift system. In order to improve the performance of hydraulic lift in precise motion, this paper proposes an MR valve with hybrid supply magnetic source and double annular channels. In addition, a structural model was established to perform pressure drop analysis. According to its working principle, it is proposed that this MR valve has two channels that work separately. There are three working modes in which the two channels work together, and the pressure drop of the MR valve can be calculated in different ways. Therefore, the MR valve with hybrid supply magnetic source and double annular channel performance test system is constructed, and the magnetic field inside the valve is simulated by performing magnetic field finite element analysis. Finally, a test bench of vehicle maintenance elevators is built to analyze whether the MR valve with hybrid supply magnetic source and double annular channels can achieve accurate control on the vehicle maintenance elevators. According to the experimental and simulation results, the pressure drop of the MR valve with hybrid supply magnetic source and double annular channels is affected by the current and channel operating mode, while the load makes little difference to the pressure drop. The worse the rising response time performance increases with increasing current, but the response time performance decreases without being affected by current. When a current greater than 1.5A is applied to the coil, the response time of the lifting platform is basically maintained at 6 s with the increase of current. The position accuracy is ±1 mm for the experimental platform of the vehicle maintenance lift table based on the MR valve with hybrid supply magnetic source and double annular channel hydraulic system.

Hybrid Data-Driven Deep Learning Framework for Material Mechanical Properties Prediction with the Focus on Dual-Phase Steel Microstructures

A comprehensive approach to understand the mechanical behavior of materials involves costly and time-consuming experiments. Recent advances in machine learning and in the field of computational material science could significantly reduce the need for experiments by enabling the prediction of a material's mechanical behavior. In this paper, a reliable data pipeline consisting of experimentally validated phase field simulations and finite element analysis was created to generate a dataset of dual-phase steel microstructures and mechanical behaviors under different heat treatment conditions. Afterwards, a deep learning-based method was presented, which was the hybridization of two well-known transfer-learning approaches, ResNet50 and VGG16. Hyper parameter optimization (HPO) and fine-tuning were also implemented to train and boost both methods for the hybrid network. By fusing the hybrid model and the feature extractor, the dual-phase steels' yield stress, ultimate stress, and fracture strain under new treatment conditions were predicted with an error of less than 1%.

Study on the Application of Vibration Isolation by Using a Trench in Frame Structures

An isolation trench is a simple and effective method to isolate structural vibrations originating from sources of vibration other than earthquakes (machines, traffic, explosions, etc.); however, there is still not a conclusive depth of the isolation trench for frame structures. To investigate the isolation effect of a trench in the frame structure designed for ground vibration, both a field test and finite element analysis were conducted to analyze the reduced effect of the vibration. The vibration reduction analysis was based on the dynamic equation and wave theory. Considering the vibration control of an industrial plant frame, a soil-trench-building finite element model was built to analyze the vibration characteristics of the floor before and after the open isolation trench structure was used. According to the model, a dynamic test was carried out on the frame structure to assess the effect of the vibration reduction by introducing the trench. The results showed that the depth of the trench was the dominating factor in vibration isolation. When the depth of the trench reached 1~1.3 times the wavelength of the Rayleigh wave, the damping effect was the strongest. the width of the trench has little effect on the vibration isolation efficiency, and the trench must be maintained at a certain distance from the building to ensure the vibration damping efficiency. The vibration of each floor was obviously reduced after the trench was built. The vibration damping effect of the trench was significant.

Field investigation and finite element analysis on expansion and shrinkage strains of expansive concrete structures

This study investigated the strain behavior of various reinforced concrete structures cast with expansive concrete. Laboratory tests, field measurement, and finite element (FE) analysis on the expansion and shrinkage were investigated. Field measurement and numerical simulation were carried out on three different structures, i.e., slab on grade (SG), slab on beam (SB), and water tank wall (WT). Strain gauges are installed in several locations in each structure to study the effects of type and amount of expansive additive and restraining conditions on the level of expansion and shrinkage. To increase the flexibility and versatility of the design process, FE analysis is one of the comprehensive methods for estimating the expansion and shrinkage strain in expansive concrete structures under restraint. FE analysis in this study applies free expansion strain as an input, with the consideration of expansion loss due to pores filling of expansive products and early age compressive creep. The field measurement results indicated that the restraint (internal and external restraint) significantly affects the expansion and shrinkage strains in the structures. Furthermore, it was found that the application of effective free strain as the input in the FE analysis made it possible to predict the level of restrained expansion strain in expansive concrete structures. The expansion and shrinkage strains can be estimated accurately using the FE analysis by considering several factors such as degree of restraint, curing conditions, and mix proportions.

Spatial distribution characterization of the Temperature-induced gradient viscoelasticity inside asphalt pavement

Under the influence of continuous periodic changes of various meteorological factors, there will be an inhomogeneous temperature field inside the asphalt pavement, which will cause a continuous gradient viscoelasticity of asphalt concrete with depth. In order to perform the structural mechanics analysis accurately, the temperature field gradient effect and the temperature-induced gradient viscoelasticity distribution inside the asphalt pavement should be revealed first. In this research, based on the heat conduction theory, a temperature field finite element analysis (FEA) model of a semi-rigid base asphalt pavement was established to investigate the distribution behavior of the temperature gradient along the depth. Dynamic modulus tests were conducted to survey temperature effect on the viscoelastic parameters of asphalt concrete. Eventually, the intrinsic relationship between temperature, depth, and viscoelastic parameters was integrated, and the relaxation time shift method was proposed to quantitatively characterize the temperature-induced gradient viscoelasticity at different depths. It is found that the temperature varies in a cubic parabolic fashion along the depth under the most significant positive and negative temperature gradient conditions. The relaxation time shift method can be effectively used to characterize the distribution of the relaxation modulus and relaxation time spectrum of asphalt concrete under the influence of temperature. It is easy to be programmed to fully consider the inhomogeneous temperature field, and applicable to both traditional and gradient FEA. The change of parameters of generalized Maxwell model for asphalt concrete with temperature is essentially the result of relaxation spectrum shifting along the relaxation time axis at different temperatures. When the temperature is high, the viscosity decreases, the relaxation spectrum shifts to the direction of decreasing relaxation time, the relaxation modulus of asphalt concrete decreases, and vice versa.

A case study on the restoration of a three-story historical structure based on field tests, laboratory tests and finite element analyses

Masonry buildings have been vulnerable structures to earthquakes due to the brittle nature of the materials used in their construction. Due to strong ground motions, the majority of masonry buildings built in seismic zones are damaged or collapsed. The performance-based evaluation of these structures must be conducted to improve their seismic performance. In this approach, the main goal is to determine structural damage, evaluate the condition of the building based on the results and decide on restoration techniques and materials. In this study, a performance-based evaluation was conducted on a three-story masonry building that was constructed in 1912, and the building was restored in response to the results. In this study, Performance Evaluation Studies are examined under four main steps: (1) Preliminary Evaluation, (2) Damage Survey Studies, (3) Detailed Evaluation Studies and (4) Restoration Implementations.

Prediction of wall deflection induced by braced excavation in spatially variable soils via convolutional neural network

Recently, the random field finite element method (RF-FEM) has attracted significantly increasing attention in the field of geotechnical engineering, especially for the purpose of analyzing the response of geotechnical systems due to the inherent variability of physical and mechanical properties. However, the method requires repeated finite element calculations based on a mass of sampling processes, making the computing effort expensive. The surrogate model is one of the techniques commonly adopted to alleviate the computational burden. In addition, some architectures of deep learning surrogate models are so unique that it is difficult to transfer to similar cases and to be familiar and reproducible by readers. In this study, we propose a convolutional neural network (CNN) surrogate model based on classical architecture, VGG6, to perform random field finite element analyses (RF-FEM). We pre-process the tabular data generated by the random filed method into an image-like format as input data. The VGG6 is used as a surrogate model to replace the original RF-FEM simulations for all subsequent calculations. The applications of the proposed method to assess wall deflection of braced excavation in clays with randomly varying cohesion cu and the friction angle φ are illustrated and compared in different cases. The excellent agreement between the VGG6 outputs and the FEM predictions demonstrated the promising potential of using VGG6s as a surrogate model for reliability analysis in spatially variable soils. Moreover, the model saves a lot of computing time and computing power and fully proves the generalization performance of the model under various cases.

Temperature Load Mode of Bridge in Permafrost Region of Qinghai–Tibet Railway

The Qinghai–Tibet railway is the plateau permafrost railway with the highest altitude and the longest line in the world. The natural conditions along the line are harsh, with many unfavorable factors such as low temperature, strong ultraviolet radiation, and large changes in daily temperature, resulting in frequent bridge damage. In order to study the bridge temperature field and its effect in the permafrost region of the Qinghai–Tibet railway, a long-term field test was carried out, and a calculation model of sunshine temperature field of concrete two-piece T-beam was established based on the principle of meteorology and heat transfer. On this basis, the beam temperature difference load mode, beam section temperature distribution law, and temperature effect were obtained. As revealed, the daily temperature difference of the Qinghai–Tibet railway bridge is large in winter, which is related to the ground’s effective radiation and surface reflectivity, and the maximum value has exceeded the current codes. The beam section temperature field shows “internal heat and external cold” in the morning and “internal cold and external heat” from noon to evening. Under the action of strong radiation and large temperature difference, bridge displacement occurs frequently, by which it is easy to cause damage to rail fasteners and bridge bearings. Based on the field test and finite element analysis, the bridge temperature difference load mode was proposed, which makes up for the deficiency that the relevant codes do not consider the plateau’s special climatic conditions and can provide a reference for the construction of plateau railways such as the Sichuan–Tibet railway.