Finite Element Method Model Research Articles

Development of a virtual reality-based zygomatic implant surgery training system with global collision detection and optimized finite element method model

Background and objectiveZygomatic implant surgery is challenging due to the complex structure of the zygomatic bone, limited visual range during surgery, and lengthy implant path. Moreover, traditional training methods are costly, and experimental subjects are scarce. MethodsTo overcome these challenges, we propose a novel training system that integrates visual, haptic, and auditory feedback to create a more immersive surgical experience. The system uses dynamic bounding volume hierarchy (BVH) and Symplectic Euler to detect global collisions between surgical tools and models, while an optimized finite element method (FEM) model simulates soft tissue and detects collisions. Compared to previous works, our system achieves global rigid-body collisions between surgical tools and patient models, while also providing stable and realistic simulation and collisions of soft tissues. This advancement offers a more realistic simulation for zygomatic implant surgery. ResultsWe conducted three experiments and evaluations. The first experiment measured the axial force generated during the zygomatic implant simulation process and compared it with actual surgery, demonstrating the realistic force rendering feedback of our system. The second evaluation involved 15 novice surgeons who experienced the system and completed a questionnaire survey focusing on five aspects. The results showed satisfactory evaluations. The third experiment involved six surgeons who underwent in-depth training for two hours daily and were tested on the first, third, and fifth days. We collected data and combined it with the doctors' feedback to prove that our system can improve surgeons' proficiency in zygomatic implant surgery and provide a novel training solution for this procedure. ConclusionWe have innovatively integrated global collision detection and optimized soft tissue simulation into our system. Furthermore, we have conducted experimental validation to demonstrate the effectiveness of this implementation. We present a novel solution for zygomatic implant surgery training.

Fluid–structure interaction with a Finite Element–Immersed Boundary approach for compressible flows

This paper presents the mathematical modeling and numerical simulations of fluid–structure interaction (FSI) problems. The fluid domain is discretized using a Cartesian block-structured mesh and solved using the Finite Volume Method (FVM), using the LES methodology with Smagorinsky turbulent closure model. The fluid flow in the system is considered compressible, with properties that vary. The Immersed Boundary Method (IBM) is used to model the solid–fluid interface, and the structure deformation was solved using the Finite Element Method (FEM). The Multi-direct Forcing Scheme is used to calculate the fluid-dynamics forces through the IBM. After calculating the fluid forces exerted on the solid, the forces are interpolated and transferred to the FEM model, providing the deformation of the structure at each time step. The structural domain was discretized with Hexahedral eight-noded element with extra shape functions. The simulations were carried out using MFSIm (in-house code), a multiphysics simulation framework developed by the Fluid Mechanics Laboratory of the Federal University of Uberlândia with financial support from Petrobras. This paper demonstrates the practical application of FSI analysis in an industrial context, specifically focusing on a pipeline system within a Fluid Catalytic Cracking Unit (FCCU) used in the oil and gas industry. The analysis involves the use of butterfly valves positioned at different angles of opening. The results are treated statistically, and a surface response is generated. Machine learning is employed to predict the surface response, showing the valve configurations that yield the maximum and minimum displacement magnitudes of the evaluated structural probes.

Analysis of Interlayer Crack Propagation and Strength Prediction of Steel Bridge Deck Asphalt Pavement Based on Extended Finite Element Method and Cohesive Zone Model (XFEM–CZM) Coupling

The extended finite element method (XFEM) was employed for the computational modeling of internal defects within a bond layer. Furthermore, a cohesive zone model (CZM) was implemented to characterize the behavior of the bond layer in response to interactions at both the bond layer/steel plate and bond layer/asphalt paving layer interfaces. The coupling of XFEM and CZM was used for a comprehensive analysis of crack propagation within the bond layer as well as the assessment of phenomena associated with interfacial debonding and delamination. The feasibility and accuracy of the XFEM–CZM coupling method were verified by comparing it with the virtual crack closure technique (VCCT), CZM, XFEM–VCCT, and experiments. A double cantilever beam experimental model was established to simulate the process of interlayer-type cracks expanding from the inside of the bond layer to the interface between the bond layer and the upper and lower layers, causing debonding. This was undertaken to analyze the damage failure mechanism of interlayer-type cracks in asphalt paving layers of steel bridge decks; to discuss the impacts of the initial crack length, the interface stiffness, the interface strength, and the thickness of the bond layer on the performance of the overall interlayer bond strength; and to carry out the significance analysis. The results showed that the initial crack length, interface stiffness, and bond layer thickness had different effects on the expansion path of interlayer cracks. The interlayer strength decreased with an increase in the initial crack length and interface stiffness, increased with an increase in the interface strength, and decreased with an increase in the thickness of the bond layer. The interface stiffness had the most significant effect on the strength.

Study on the applicability of the single cable model in cable force identification of in-service beam string structures

At present, the frequency-based cable force identification method based on single cable model assumption is still one of the most popular methods for its efficiency and convenience. However, the applicability of the single cable model assumption in the cable force identification of complex structures such as beam string structures (BSS) is worth of studying for the cables in BSS are usually short and thick, and the joints connection are complex, the cable force-frequency relationship will be possibly affected by the boundary assumption. Therefore, this paper studies the applicability of the single-cable model hinged at both ends in the cable force identification of BSS from the perspective of overall structure. Firstly, the finite element method (FEM) models for the overall BSS are established to describe the true parameters and boundary conditions of each cable within the BSS. Secondly, a “Three-criteria method” is conducted for extracting the local modes of each cable element from the global modes of the overall structure under pre-designated cable forces; and then the cable force-frequency correlation considering the influence of overall structure can be established. On this basis, the error magnitude of the single-cable model hinged at both ends for frequency-based cable force identification is analyzed corresponding to the changes of different sensitive factors. Some meaningful conclusions are obtained. Finally, the effectiveness of the method and the conclusions in this paper is verified by the testing data of an actual truss string project. The research in this paper provides a foundation for further research on improving the identification precision.

Soft pneumatic actuator workspace augmentation with synthesis of simplified analytical and numerical subcomponent models

Chamber inflating soft pneumatic actuators (SPA) are widely used for many industrial applications. Despite the increasing popularity of the actuators, few analyses investigating the detailed functionality of the actuator subcomponents and the contribution of their functions to the overall actuator operation are available. Understanding the roles of the actuator’s (sub)components for the overall actuator motion is the fundamental motivation of this work. Consequently, this paper must evaluate the interactions between the actuator’s overall performance and the component-level design parameter variations. To understand the relation, this work builds component-level simplified analytical models and extends them to estimate the actuator motions. With finite element method (FEM) models, the work enhances its analysis of each component and confirms their contribution to the overall motion. Both the newly built analytical and FEM models are thoroughly compared to a series of experiments. Finally, the present work synthesizes the studied design sensitivity of the subcomponent variations and suggests a soft pneumatic actuator design that is believed to provide the maximum workspace.

Heat generation induced by plastic deformation during particle normal impact

Energy dissipation during particle impact has been widely studied in different fields where material plastic deformation is one of the main dissipation mechanisms. However, heat generation associated with plastic deformation is hardly accounted for, particularly in granular flows. This work investigates this problem at a particle level for the normal impact between an elastic-perfectly-plastic particle and a rigid substrate. The finite element method (FEM) and theoretical models are used to predict the net generated heat. It is shown that the FEM model agrees with the theoretical model especially when the coefficient of restitution is estimated accurately. In addition, the FEM model is used to study the temperature evolution for various impact velocities and material properties. It is found that the highest temperatures are generally in the subsurface. This observation confirms that the heat generation associated with plastic deformation is indeed a volumetric phenomenon, in contrast to the surface action conventionally assumed in the case of dissipation by friction.

Evaluation of pH variation in cathodic protection conditions by FEM simulation

AbstractCathodic protection is an electrochemical technique used to control the corrosion of metals. It does this by sending a proper amount of current equal to the current required by the cathodic processes at the protection potential. One of the chemical effects of cathodic protection is a local pH increase at the surface, which is an important factor in the reduction of corrosion rate, as carbon steel may work in a passive condition. In the present study, a tertiary current distribution finite element method model is introduced. A dynamic boundary condition is considered, by defining a Fe anodic Tafel slope as a pH function, and oxygen reduction reaction limiting current density as a function of available oxygen at the cathode surface. The model has been validated by direct pH measurement during a short‐term polarization test, and subsequently used to predict the pH and the available oxygen at the cathode surface for long‐term condition.

Seismic behaviors of CFT-column frame-four-corner bolted connected buckling-restrained steel plate shear walls using ALC/RAC panels

A Frame-Buckling Restrained Steel Plate Shear Walls (BRSPSWs) system has been designed, featuring a steel plate connected to frame elements, to withstand lateral loads like seismic or wind forces. This system incorporates recycled aggregate concrete (RAC) to create concrete-filled and concrete panels, promoting eco-friendly and sustainable construction materials. Two single-span, two-floor specimens were tested under cyclic quasi-static load. A four-corner bolted connection was used to connect the steel plate to the square concrete-filled steel tubes (CFTs) column and H-section beam, minimizing the potential deformation of the frame elements produced by the tension field of the steel plate after high-order bucking. The steel plate was sandwiched using either autoclaved lightweight concrete (ALC) or RAC panels. The study analyzed failure modes, load-displacement responses, and characteristic capacities. Test results inferred that BRSPSWs exhibited favorable cyclic behavior, with similar failure modes observed using both ALC and RAC panels. The buckling of steel plates was reduced, and the type of restrained panels had a negligible impact on buckling. Consequently, ALC panels can effectively replace RAC panels. Furthermore, bearing capacities and yield stiffness were primarily determined by the bolted connection forms. A finite element (FE) modeling was developed using ABAQUS software and validated against test results. This FE modeling method successfully simulated failure modes and load-displacement curves. Parametric analyses were conducted and revealed that bearing capacity and yield stiffness positively correlated with steel plate thickness, bolt diameter, and the number of bolts but negatively correlated with the axial compression ratio. In contrast, the panel thickness and span length had a minor impact due to shear deformation in the bolted connection. Based on the test results and parametric studies, an equation for the yield-bearing capacity of BRSPSWs was proposed and verified.

Investigating the effectiveness of deep cement mixing in deep sea: A static load testing case study

This research demonstrated a marine reclamation project in Hong Kong's deep-sea region, which employed the economically efficient and environmentally sustainable deep cement mixing (DCM) clusters for the reconstitution of marine sediments. This study offers a detailed introduction to the installation of DCM clusters and the conduction of subsequent static loading tests, providing experiences for forthcoming endeavors in marine reclamation, particularly in regions akin to Hong Kong. To ensure that both compressions and lateral movements do not exceed the acceptance criteria, the finite element method (FEM) was employed to navigate the construction of DCM clusters effectively. Subsequently, static load tests were conducted, with meticulous measurement of compressions and lateral movements. The results show that the maximum vertical compression and lateral movements are approximately 4 mm and 10.8 mm, respectively, which are significantly beneath the corresponding acceptance criteria (i.e., 40 mm and 60 mm for vertical and lateral movements). A comparison between field measurement outcomes and simulation results supported the capability of FEM in identifying the crucial movement characteristics of DCM clusters, albeit a discernible discrepancy, predominantly being attributed to the conservative parameters utilized in the FEM model as per existing specifications. This delineation underscores the imperative need for the development of region-specific guidelines.

Nonlinear electromechanical bending of bi-modular piezoelectric laminated beams

In this paper, the nonlinear electromechanical bending of a bi-modular piezoelectric laminated beam is studied based on the principle of minimum potential energy and the Adomian decomposition method. The different tensile-compressive Young’s modulus of the core and piezoelectric layers, and the different tensile-compressive piezoelectric coefficients are considered. The electromechanical governing equations and related boundary conditions are obtained by using the principle of minimum potential energy. The deflection, neutral layer and interlaminar stresses of the beam are solved by the Adomian decomposition method and the iterative method, and verified by the finite element model and Galerkin's method. Results show that the applied voltage and the bi-modular characteristics affect the position of the neutral layer and the interlaminar stresses. Compared with the bi-modular properties of the core layer, the influences of the bi-modular properties of the piezoelectric layer on the neutral layer are relatively unobvious. In addition, the interlaminar stresses between the piezoelectric layer and core layer can be increased or decreased, depending on the relative magnitude of the applied voltage ratio and the bi-modular ratio. The results obtained are helpful for the analysis of the electromechanical coupling mechanism and design of piezoelectric composites and structures with bi-modular characteristics.

Dynamic mechanical response prediction model of honeycomb structure based on machine learning method and finite element method

In this study, a novel framework was presented for accelerating the prediction of the mechanical response of honeycomb structures under dynamic crushing, using 2D cells to surrogate 3D honeycomb structures by machine learning (ML). The sizes of different honeycomb structures were designed and the necessary training data obtained through finite element (FE) simulations, but without using any explicit design parameters of the honeycomb cells in the ML model. A pixelization method of FE model was proposed to separate the complete cell structure from the honeycomb FE grid data and convert it into a matching pixel map. FE data was structuralized while reducing the large amount of computational power consumed in identifying complex array structures. Unsupervised automatic extraction of low-dimensional features of pixel maps was performed using a convolutional denoising autoencoder (CDAE). The crushing velocity and the extracted latent features were used as the input of the long-short term memory (LSTM) network to predict the crushing deformation and stress-strain curve of the honeycomb structure under different dynamic loading. Results showed that the constructed ML model could describe the dynamic crushing response behavior. Compared with the traditional FE method, the prediction model was 4.45 × 103 and 1.05 × 103 times faster in predicting the stress-strain and structural deformation response, respectively. The mechanical response prediction model provided a method for rapidly evaluating the dynamic mechanical response behavior of similar periodic array structures using FE model data, which could be beneficial for the design and development of equipment based on bionic structures.

Grounded source transient electromagnetic 3D forward modeling with the spectral-element method and its application in hydraulic fracturing monitoring

A long wire with large current source transient electromagnetic (TEM) monitoring, with a large detection depth, low cost, safety, and environmental protection, has unique advantages in the testing and identification of unconventional reservoir fluid and the evaluation of stimulated reservoir volume. So, the TEM 3D forward modeling method has become a research hotspot. Although the finite-element method (FEM) is a type of numerical algorithm that has been widely applied in three-dimensional (3D) electromagnetic field forward modeling, the efficiency and accuracy of FEM require further improvement in order to meet the demand of fast 3D inversion. By increasing the order of the basis function and adjusting the principle of mesh discretization, the precision of the mixed-order spectral-element (SEM) result will be increased. The backward Euler scheme is an unconditionally stable technique which can ignore the impact of the scale of the time step. To achieve a better description of the nonlinear electromagnetic (EM) response of the grounded source TEM method and to optimize the efficiency and accuracy/precision of the 3D TEM forward modeling method significantly, we proposed the use of 3D TEM forward modeling based on the mixed-order SEM and the backward Euler scheme, which can obtain more accurate EM results with fewer degrees of freedom. To check its accuracy and efficiency, the 1D and 3D layered models are applied to compare the SEM results with the semi-analytical and FEM solutions. In addition, we analyzed the accuracy and efficiency of the SEM method for different types of order basis functions. Finally, we calculated the long-wire source TEM response for a practical 3D earth model of a shale gas reservoir for fracturing monitoring and tested the feasibility of the TEM method in a hydraulic fracturing monitoring area to further demonstrate the flexibility of the SEM method.

Optimisation Design of a Low-Frequency Eddy Current Rail Heater

The aim of the work is the optimisation of a rail heater, constituted by a magnetic core supplied by a sinusoidal current, which induces an eddy current in the rail. Optimisation parameters are electrical and geometrical quantities: supply frequency, voltage amplitude, airgaps, and core shape, while objectives are power transferred to the rail, absorbed current, and power distribution index. Optimisation is performed by an accurate field analysis, provided by the finite element method (FEM), coupled to an automated multiobjective procedure based on fuzzy logic. Particular care has been devoted to the FEM model in order to take into account important phenomena as non-linearity magnetic behaviour and non-uniform distribution of current in the rail caused by eddy currents.

A coupled model of finite element method and Mie theory for heat transfer inside expanded perlite vacuum insulation panels (VIPs) at high temperatures

The present study introduces the first coupled model of the finite element method and Mie theory that predicts the heat transfer mechanism inside the expanded perlite vacuum insulation panels at a temperature range of 300–800 K. The finite element method is applied to discretise the governing equation of the steady state heat transfer and the three-dimensional Fourier's law is used. COMSOL Multiphysics is the finite element numerical solver which predicts solid and gaseous thermal conductivity inside the VIPs. Moreover, Mie theory predicts the radiative conductivity. Heat transfer radiation is superimposed on the heat transfer through conduction. The model is capable of predicting total thermal conductivity of VIPs at high temperatures ≥ 500 K, which makes it a unique model with clear advantage over previously developed numerical models. The numerical predictions of the developed coupled model are validated experimentally. The predictions of the coupled model are in good agreement with the experimental measurements, which indicate the capability of the developed model to predict the mechanisms of heat transfer at high temperatures. For instance, the values of total thermal conductivity for numerical prediction and experimental measurement, at 557 K, are 14.6 and 14.7±1.2 mW/m/K, respectively, excellently agreeing within ± 8.9 %.

Investigation into the fracture behavior of ZK60 Mg alloy rolling sheet under different stress triaxiality

In order to investigate the fracture behavior of the ZK60 Mg alloy rolling under different stress triaxiality, the different nominal stress triaxiality samples were well-designed, and the in-situ DIC tensile tests were carried out. The finite element method (FEM) model was validated by experimental results and the stress triaxiality evolution of samples was determined by modeling. The fracture strain of the ZK60 Mg alloy was non-monotonic with the nominal stress triaxiality increase and the best deformation performance of the central hole sample was indicated via the experimental and modeling results. The low stress triaxiality gradient of the central hole sample led to better deformation performance in terms of the macroscopic mechanical response. The transformation of the fracture mechanism from shear transgranular fracture to intergranular fracture and then to transgranular fracture during the stress triaxiality increased from 0 to 2/3 and was revealed via scanning electron microscope (SEM) characterization and FEM modeling. To further confirm the above fracture mechanism, X-ray computed tomography (XCT) was carried out to characterize the micro damage volume fraction and morphology. Due to the transgranular fracture induced by the high stress triaxiality at the initial fracture position of the central hole sample, the micro damage was smaller, delaying the fracture failure and achieving higher strain.

Identification of damage in steel beam by natural frequency using ANNS models

Beams have played a significant role in engineering applications and they have been commonly used for modelling civil problems. In fact, different models and methods have been developed to identify the damage to the beams. In this paper, the artificial neural network (ANN) model was developed to predict the location, width and depth of the saw-cut of steel beams by the change of natural frequencies. The natural frequencies of a steel beam in different scenarios were identified by the Finite Element Method (FEM). In order to validate the accuracy of FEM model, the natural frequencies of the steel beam in the case of no saw-cut determined by this model were compared with those determined by the Frequency Domain Decomposition (FDD) method. The results indicated that, the combination of FEM method, FDD method and ANN model would have great significance in structure health monitoring.

The Behaviour of Thin-Walled Cylinders with Reinforcing Inner Walls Subjected to High-Velocity Impact

Thin cylindrical tubes as impact energy absorbers have been widely used in various fields. Previous researchers have proposed many methods to increase the ability to absorb energy by modifying the geometry or using different materials. This study discusses using reinforcing walls in the cylinder to increase energy absorption capability. We make thin cylindrical specimens made of aluminium alloy with a length of 150 mm, a diameter of 50 mm, and a thickness of 1 mm. Reinforcing walls are fitted in the cylinder with a vertical position of 1, 2, 3, and without supporting walls. An impactor moving at high velocity hits the up-end cylinder in the axial direction. The finite element method modelling results show that installing reinforcing walls in thin-walled cylinders increase the maximum impact force, decreases the maximum deformation, changes the deformation mode, and increases the energy absorption capability. The amount of wall added to the thin wall will affect the impact behaviour of the specimen. However, in this study, the presence of a wall will have an effect when the deformation reaches the location of the wall. Nevertheless, using this reinforcing wall also makes the manufacturing process more complex. Therefore, this study’s results are recommendations for the design of the impact energy absorption structural system.

Study on the Vibration and Sound Radiation Performance of Micro-Perforated Laminated Cylindrical Shells

In response to the problem of vibration and noise reduction in equipment with cylindrical shell structures, this paper focuses on the micro-perforated laminated cylindrical shell structure and establishes its finite element model. Through comparative analysis with experimental results, the reliability of the finite element modeling method is verified. Based on this, the paper places particular emphasis on the vibration and acoustic radiation performance of the structure in the 1–1000 Hz frequency range under free conditions to understand the impact of different laminated shell structures, micro-perforation parameters (porosity, aperture), sound-absorbing foam materials, and placement methods. The results indicate that micro-perforated structures can efficiently reduce the structural radiated sound power level at specific frequencies, but the overall reduction in radiated sound power level is not significant. Various types of foam are effective in reducing the structural radiation acoustic power level, with polyurethane performing best among them. Changing the location of foam placement has a relatively insignificant impact on the structural radiation acoustic power level.

Fabry–Perot Cavity Optimization for Absolute Strain Sensing Using Finite Element Analysis

The finite element method (FEM) was used to investigate the optical–mechanical behavior of a Fabry–Perot Interferometer (FPI) composed of a capillary segment spliced between two sections of standard optical fiber. The developed FEM model was validated by comparing it with theory and with previously published experimental data. The model was then used to show that the absolute strain on the host substrate is usually smaller than the strain measurement obtained with the sensor. Finally, the FEM model was used to propose a cavity geometry that can be produced with repeatability and that yields the correct absolute strain experienced by the host substrate, without requiring previous strain calibration.

Ultrasonic Non-Contact Air-Coupled Technique for the Assessment of Composite Sandwich Plates Using Antisymmetric Lamb Waves

This paper describes the design and implementation of an ultrasonic non-contact air-coupled technique (UNCACT) using antisymmetric Lamb waves (ALW) for NDT assessments in novel composite sandwich plates of a car body shell. This technique is complemented with a C-Scan image implementation using guided waves. The finite element method (FEM) was developed using Comsol 6.1 for the interpretation of the several wave modes presented in the experiments, including the ALW mode. This FEM model is indispensable for the correct interpretation of the received signals and contributes to a better implementation of this technology. This is a novel contribution building upon previously reported work. Additionally, the phase velocity method (PVM) was applied for the verification of the ALW mode in the portion of the RF signal necessary for the C-Scan image.