Finite Element Simulation Techniques Research Articles

Optimization of electromagnetic layout for E-machine in electric vehicles: Achieving high performance, efficiency and NVH

The development of electric vehicles (EVs) presents the challenge of optimising electric machines to enhance efficiency, compactness, noise, vibration, harshness (NVH), and affordability, while reducing the dependence on heavy rare-earth materials to reduce the CO2 footprint of electric powertrains. This paper introduces a comprehensive optimization approach for the electromagnetic design of permanent magnet synchronous machines (PMSMs), employing a combination of Design of Experiment (DoE) and Robust Neural Networks (RNN). The optimization framework is utilised to comprehensively address the multiple objectives of an electric machine, including efficiency, noise, vibration, harshness (NVH), and cost. The integration of Artificial Intelligence (AI)-driven modelling has resulted in significant performance improvements, achieving up to 96% total efficiency over the entire load cycle with substantial NVH reductions of up to 20 dB, while reducing the magnet rare earth materials by 35% compared to the baseline. Furthermore, this methodology reduces the simulation time by up to 90%, demonstrating the potential of combining neural network optimization with conventional finite element simulation techniques. The validation of the AI-driven optimization approach with the measurement of the baseline and optimised electric machines for efficiency and vibration is demonstrated for correlation.

Design of petal-shaped probe for pulse eddy current testing based on finite element simulation

Abstract This paper employs finite element simulation techniques to devise an innovative array-type petal-shaped pulsed eddy current testing probe and investigates its distinctions related to conventional cylindrical probes. Within the simulation framework, a thorough comparative analysis of the detection capabilities of the two probe types is conducted, encompassing an examination of the eddy current regions formed, the impact of lift-off effects and sensitivity to circular corrosion defects. The simulation outcomes reveal that the probe designed in this study exhibits a more extensive detection range and superior detection performance in comparison to its counterparts. This observation holds significance for defect detection in coated materials and the refinement of pulsed eddy current testing probe designs.

Machine learning assisted prediction and analysis of in-plane elastic modulus of hybrid hierarchical square honeycombs

In this study, experimental, finite element (FE) simulation, machine learning (ML), and theoretical techniques are employed to investigate the in-plane elastic modulus (EHHSH) of hybrid hierarchical square honeycombs (HHSHs). First, HHSHs with different configurations were fabricated using a 3D printer, and in-plane quasi-static compression tests were conducted on them. Then, 234 FE models are simulated to determine the EHHSH of HHSHs with various configurations, and the results are used to train 11 ML models. Comparative analysis demonstrates that the Extreme Gradient Boosting (XGBoost) model has the best predictive capability. Moreover, a modified theory for EHHSH is established based on the XGBoost model and existing theory, and its exceptional predictive capability is verified by comparing with experimental, FE, and existing theoretical results. Finally, the upper and lower bounds of EHHSH are determined by the modified theory, and the Shapley Additive Explanation (SHAP) method is used to identify the importance of different geometric parameters on tailoring EHHSH. The combination of theoretical and ML techniques provides a promising approach for developing a robust prediction model of material properties.

Computational and Experimental Analysis of Surface Residual Stresses in Polymers via Micro-Milling.

This research conducts an in-depth investigation into the residual stresses in resin micro-milling processes. Considering that resin is the most crucial matrix material in composites, the construction of a precise machining theory for it is not only key to achieving high-quality- and efficient processing of composite materials but also fundamental to enhancing the overall performance of the materials. This paper meticulously examines the surface integrity and accuracy of epoxy polymers following precision machining, primarily revealing the significance of residual stresses and size effects in extending the lifespan of precision components and promoting their miniaturization. We have adopted an innovative finite element (FE) simulation method, integrated with the Mulliken-Boyce constitutive model, to profoundly analyze the impacts of residual stresses on the surfaces and sub-surfaces of thermosetting polymers. This research further explores the influence of critical machining parameters such as chip thickness, cutting edge radius, feed per tooth, and axial depth on cutting forces, as well as the inherent size effects in polymers. Utilizing X-ray diffraction (XRD) technology, we accurately measured the residual stresses generated during the micro-milling process. The close correlation between FE simulations and experimental results validates the accuracy and effectiveness of our method. This study represents a substantial breakthrough in finite element simulation techniques for high-precision machining of polymer materials, injecting valuable theoretical and practical knowledge into the field.

Pre‐insertion resistors temperature prediction based on improved WOA‐SVR

AbstractThe pre‐insertion resistors (PIR) within high‐voltage circuit breakers are critical components and warm up by generating Joule heat when an electric current flows through them. Elevated temperature can lead to temporary closure failure and, in severe cases, the rupture of PIR. To accurately predict the temperature of PIR, this study combines finite element simulation techniques with Support Vector Regression (SVR) optimized by an Improved Whale Optimization Algorithm (IWOA) approach. The IWOA includes Tent mapping, a convergence factor based on the sigmoid function, and the Ornstein–Uhlenbeck variation strategy. The IWOA‐SVR model is compared with the SSA‐SVR and WOA‐SVR. The results reveal that the prediction accuracies of the IWOA‐SVR model were 90.2% and 81.5% (above 100°C) in the ± 3°C temperature deviation range and 96.3% and 93.4% (above 100°C) in the ± 4°C temperature deviation range, surpassing the performance of the comparative models. This research demonstrates that the method proposed can realize the online monitoring of the temperature of the PIR, which can effectively prevent thermal faults PIR and provide a basis for the opening and closing of the circuit breaker within a short period.

Ti-PEEK interpenetrating phase composites with minimal surface for property enhancement of orthopedic implants

Bioinspired interpenetrating phase composites (IPCs) present a promising strategy for augmenting the mechanical properties of materials, thereby synergistically enhancing the strength and fracture toughness of orthopedic implants. In this study, Ti6Al4V-PEEK IPCs were fabricated by pressing molten PEEK into additively manufactured Ti6Al4V scaffolds designed using minimal surface structures. The mutual spatial interpenetration and strong binding between Ti and PEEK were confirmed through CT detection and SEM analyses, revealing the presence of continuous constituents within biomimetic architectures. Due to interpenetration promoting interaction and efficient stress transfer of the two phases, IPCs enhances toughness and energy absorption by over 291% and 309% respectively while maintaining bone-compatible elastic modulus and higher strength. The mechanisms underlying stress dispersion, crack propagation resistance, and prolonged stress plateau period of IPCs were investigated through the utilization of digital image correlation (DIC) and finite element simulation techniques. Among the various types of IPCs investigated, Gyroid IPCs exhibit superior comprehensive mechanical properties, thereby facilitating the development of customized IPCs aimed at ensuring long-term stability in orthopedic implantation scenarios.

Numerical and experimental investigations of mechanical, tribological, and electrical properties of laminated Bi-metal Al/SiC/Ni composites

Bimetal pure Al/SiC/Ninanocomposites are a remarkable class of nanocomposite materials with a layered structure comprising pure aluminum, silicon carbide nanoparticles, and nickel. The ingenious design of these nanocomposites aims to synergistically combine the desirable properties of each constituent material, resulting in an exceptional enhancement of mechanical, thermal, and electrical characteristics. This study focused on fabricating 1-mm bimetal pure Al/SiC/Ni nanocomposites using an accumulative roll bonding process. The rolling process was conducted for eight cycles at a controlled temperature of 250 °C. To understand the behavior of the bonding interface between the aluminum/nickel layers, a comprehensive investigation was carried out using finite element simulation techniques. The study specifically delved into the bonding mechanisms between the aluminum and nickel layers, employing simulation and experimental procedures. A series of rigorous tests were conducted to evaluate the resulting nanocomposites comprehensively. These included tensile strength tests, peeling tests, average Vickers micro hardness tests, wear-resistant tests, electrical resistance testing, and scanning electron microscopy analysis. These tests thoroughly examined the evolution of the microstructure and the nanocomposites’ mechanical properties. The obtained results conclusively demonstrate that the supplementary accumulative roll bonding process led to substantial improvements in the nanocomposites’ mechanical properties, wear resistance, and electrical resistance properties. Furthermore, the simulation results indicate that the optimal bonding conditions, characterized by robust interfacial bonding, were achieved at higher cumulative rolling cycles.

In-plane energy absorption characteristics and mechanical properties of 3D printed novel hybrid cellular structures

This paper developed and fabricated four novel hybrid metamaterial structures by combining honeycomb, re-entrant, and star-shaped unit-cells by additive manufacturing (AM) techniques and tested them to evaluate the enhanced mechanical properties. Then, the in-plane energy absorption capacity and uniaxial compressive response of novel structures were compared using finite element simulation and experimental techniques. In addition, all structures' failure modes and deformation mechanisms were explained in detail. A type one re-entrant-star-shaped (RS1) structure demonstrated higher compressive strength, plateau stress, and energy absorption than other structures, mainly due to the unique deformation mechanism. For comparing energy absorption and mechanical properties between the parent and hybrid cellular structures (HCS), the RS1 performed the best. A Poisson's ratio curve for HCS was also obtained, and the relevant results were analyzed. In addition, the results of this research should aid in determining the best unit-cell arrangement for HCS to improve their mechanical properties and energy absorption.

Field test and numerical simulation of a full-scale RC pier under multiple lateral impacts

In recent years, the frequent occurrence of vehicle-pier collision accidents have highlighted the necessity of the research on the impact resistance of bridge piers; but until now, most of the studies employed numerical simulations or indoor reduced-scale tests, while the collision tests regarding full-scale reinforced concrete (RC) piers with actual foundations are still scarce. In order to obtain the most realistic impact responses and damage characteristics of RC pier, six successive lateral impact tests on a full-scale RC single-column pier with a monopile foundation were conducted in this study based on a self-designed large-size slide device and a rigid model vehicle. The mass of the model vehicle was 2205 kg and the impact velocity ranged from 3.17 m/s to 8.22 m/s. The tests obtained valuable test data such as vehicular impact forces, and lateral displacements, accelerations and damage pattern of the RC pier under all the six collision trials. Furthermore, finite element (FE) simulations were also performed and validated against the test results, where several problems of the commonly-used FE simulation techniques are revealed. In addition, the influences of multiple (successive) impacts on the impact forces and dynamic behavior of the pier are also discussed in this paper. This study provides valuable experimental data for the current research on RC piers subjected to vehicle collisions, and also references for the numerical simulations and theoretical analysis of RC columns under multiple lateral impacts.

Room-Temperature Sodium-Sulfur Batteries: Rules for Catalyst Selection and Electrode Design.

Seeking an optimal catalyst to accelerate conversion reaction kinetics of room-temperature sodium-sulfur (RT Na-S) batteries is crucial for improving their electrochemical performance and promoting the practical applications. Herein, theoretical calculations of interfacial interactions of catalysts and polysulfides in terms of the surface adsorption state, interfacial ions migration, and electronic concentration around the Fermi level are systematically proposed as guiding principles of catalyst selection for RT Na-S batteries. As a case, MoN catalyst is accurately selected from transition metal nitrides with different d orbital electrons, and for experiment, it is introduced into the carbon nanofibers as a dual-functioning host (MoN@CNFs). The MoN@CNFs can effectively anchor polysulfides and accelerate their conversion reaction. In addition, for the sodium anode, the MoN@CNFs can also induce uniform deposition of Na and inhibit dendrite growth, which are supported by in situ characterizations and finite element simulation technique. As a result, the as-prepared RT Na-S battery displays high reversible capacity of 990 mAh g-1 at 0.2 A g-1 after 100 cycles and long lifespan over 1500 cycles at 2 A g-1 . Even with high S loading of 5mg cm-2 , the RT Na-S battery still exhibits a high areal capacity of 2.5 mAh cm-2 .

Evaluation of Pavement Treatment Strategies for Friction-Deficient Horizontal Curves

In friction management of horizontal-curve pavements, highway agencies develop treatment strategies for friction-deficient pavements mainly based on past experience or industry recommended practices. In the absence of an engineering procedure to evaluate the effectiveness of friction treatments, there is no sound basis for comparing the effectiveness of different treatment strategies. To overcome this limitation, this study explored a mechanistic approach to analyze friction treatments for a horizontal curve and compare the magnitudes of skid resistance improvement, reductions of skidding potential, and terminal polished skid resistance. This was achieved by applying the finite element simulation technique to calculate the tire–pavement skid resistance available and the safe vehicle speeds under a given set of design operating conditions. For illustration, five friction treatments for pavement curves were analyzed: resurfacing/overlay, high-friction resurfacing, longitudinal grooving, transverse grooving, and resurfacing/overlay plus raising of superelevation. The skid resistance, safe vehicle speed, and terminal skid resistance were determined for different wet-weather operating conditions. The operating conditions were defined by horizontal-curve geometric parameters, pavement surface properties, wheel load, geometric and structural properties of tire, and water film thickness. The effectiveness of an improvement treatment is evaluated by skid resistance improvement, skidding potential reduction, and terminal polished skid resistance. Two quantitative indicators were introduced for effectiveness evaluation: safe skid resistance margin ΔSN and safe vehicle speed margin ΔV. The proposed approach presents a quantitative engineering assessment procedure for highway agencies in the selection of a suitable treatment, and maintenance planning in their friction management of horizontal-curve pavements.

Finite Element Simulation Technique for Evaluation of Opening Stresses Under High Plasticity

Abstract The crack closure phenomenon is important to study as it estimates the fatigue life of the components. It becomes even more complex under low-cycle fatigue (LCF) since under LCF high amount of plasticity is induced within the material near notches or defects. As a result, the assumptions used by the linear elastic fracture mechanics (LEFM) approach become invalid. However, several experimental techniques are reported on the topic, the utilization of numerical tools can provide substantial cost and time-saving. In this study, the authors present a finite element simulation technique to evaluate the opening stress levels for two structural steels (25CrMo4 and 30NiCrMoV12) under low-cycle fatigue conditions. The LCF experimental results were used to obtain kinematic hardening parameters through the Chaboche model. The finite element analysis (FEA) model was designed and validated, following the fatigue crack propagation simulation under high plasticity conditions using abaqus. Crack opening displacement versus stress data were exported from abaqus, and 1.5% offset method was employed to define opening stress levels. Numerical simulation results were compared with the experimental results obtained earlier through the digital image correlation (DIC) technique. To conclude, FEA could be a valuable tool to predict crack closure phenomena and, ultimately, the fatigue life of components. However, analysis of opening stresses using crystal plasticity models or extended finite element method (XFEM) tools should be explored for a better approximation in future studies.

The Optimization of Ti Gradient Porous Structure Involves the Finite Element Simulation Analysis

Titanium (Ti) and its alloys are attracting special attention in the field of dentistry and orthopedic bioengineering because of their mechanical adaptability and biological compatibility with the natural bone. The dental implant is subjected to masticatory forces in the oral environment and transfers these forces to the surrounding bone tissue. Therefore, by simulating the mechanical behavior of implants and surrounding bone tissue we can assess the effects of implants on bone growth quite accurately. In this study, dental implants with different gradient pore structures that consisted of simple cubic (structure a), body centered cubic (structure b) and side centered cubic (structure c) were designed, respectively. The strength of the designed gradient porous implant in the oral environment was simulated by three-dimensional finite element simulation technique to assess the mechanical adaptation by the stress-strain distribution within the surrounding bone tissue and by examining the fretting of the implant-bone interface. The results show that the maximum equivalent stress and strain in the surrounding bone tissue increase with the increase of porosity. The stress distribution of the gradient implant with a smaller difference between outer and inner pore structure is more uniform. So, a-b type porous implant exhibited less stress concentration. For a-b structure, when the porosity is between 40 and 47%, the stress and strain of bone tissue are in the range of normal growth. When subject to lingual and buccal stresses, an implant with higher porosity can achieve more uniform stress distribution in the surrounding cancellous bone than that of low porosity implant. Based on the simulated results, to achieve an improved mechanical fixation of the implant, the optimum gradient porous structure parameters should be: average porosity 46% with an inner porosity of 13% (b structure) and outer porosity of 59% (a structure), and outer pore sized 500 μm. With this optimized structure, the bone can achieve optimal ingrowth into the gradient porous structure, thus provide stable mechanical fixation of the implant. The maximum equivalent stress achieved 99 MPa, which is far below the simulation yield strength of 299 MPa.

Validation of the mechano-bactericidal mechanism of nanostructured surfaces with finite element simulation

The mechano-bactericidal property of nanostructured surfaces has become the focus of intensive research toward the development of a new generation of antibacterial surfaces, especially in the current era of spreading antibiotic resistance. However, the mechanisms underlying nanostructured surfaces mechanically damaging bacteria remain unclear, which ultimately limits translational potential toward real-world applications. Using finite element simulation technique, we developed the three-dimensional thin wall with turgor pressure finite element model (3D-TWTP-FEM) of bacterial cell and verified the reliability of this model by the AFM indentation experiment simulation of the cell, and the cell model is able to simulate suspended bacterial cell and the process of cell adhering to the flat and nanopillar surfaces. Since bacterial cells suffer greater stress and deformation on the nanopillar surfaces, a two-stage model of the elastic and creep deformation stage of the cells on the nanostructured surfaces was developed. The calculations show that the location of the maximum stress/strain on the cells adhered to the nanopillar surfaces is at the liquid-cell-nanopillar three phase contact line. The computational results confirmed the ability of nanostructured surfaces to mechanically lyse bacteria and gave the effect of nanopillar geometry on the efficiency and speed of bacterial cell rupture. This study provides fundamental physical insights into how nanopillar surfaces can serve as effective and fast mechanical antimicrobial materials.

Evaluation of Modelling and Simulation Strategies to Investigate the Mechanical Integrity of a Battery Cell Using Finite Element Methods

The mechanical integrity of a lithium ion battery cell can be evaluated using finite element (FE) simulation techniques. In this study, different FE modelling approaches including heterogeneous, homogeneous, hybrid and sandwich methods are presented and analysed. The basic capabilities of the FE-methods and their suitability to simulate a real mechanical safety test procedures on battery cells are investigated by performing a simulation of a spherical indentation test on a sample pouch cell. For each modelling approach, one battery cell model was created. In order to observe the system behaviour, relevant parametric studies involving coefficient of friction and failure strain of separator were performed. This studied showed that these parameters can influence the maximum force and the point of failure of the cell. Furthermore, the influence of an anisotropic separator on the results was also investigated. The advantages and disadvantages of each modelling approach are discussed and a simplified approach with a partial cell modelling is suggested to further reduce the simulation time and complexity.

Highly flexible cover window using ultra-thin glass for foldable displays

The market for next-generation flexible displays is rapidly expanding with the launch of foldable electronic products. Consequently, the flexible electronic material and device industries are continuously growing. Specifically, the cover window used in foldable displays is a very important component that must have excellent optical, physical, and mechanical characteristics while withstanding high external stresses caused by the bending radius, unlike the existing rigid-type cover windows. Considerable research efforts have been dedicated toward improving their performance. In this study, a cover window substrate for a foldable display having high flexibility was developed. To this end, ultra-thin glass (UTG) with excellent flexibility and transparency was used to overcome the low surface hardness of the typical polymer substrate used in existing foldable substrates. In addition, for efficient stress control, the design of the multilayer structure was optimized by generating multiple neutral planes through the use of an optical clear adhesive (OCA) buffer layer. The structure of the cover window was designed using the finite element simulation technique, and actual samples of the cover window with the optimized structure were produced to evaluate their physical, mechanical, and optical characteristics. As a result, the optimized foldable cover window showed a surface hardness of 9 H and a light transmittance of 90 %; especially, it exhibited an excellent bending reliability with 200000 bending repetitions without failure at the small bending radius of 1.5 R.

Characterization of a standard pneumatic piston gauge using finite element simulation technique vs cross-float, theoretical and Monte Carlo approaches

Simulation techniques when applied for metrological estimations have recently emerged as a tool for potential improvement in design and performance aspects. The current paper reports one such application for the numerical estimation of the distortions and strains developed in a standard piston gauge leading to the estimation of the effective area and the pressure distortion coefficient up to a pressure of 4 MPa, through the application of finite element analysis (FEA) technique and a comparative analysis of its outcome with the experimentally and theoretically determined values as well as the Monte-Carlo simulation results. The experimental characterization was done using cross-floating method while theoretical approach used the Dadson's equations. The strain values for the piston-cylinder assembly under pressure, obtained from the FEA simulation, were used to calculate the distortions in the piston and cylinder, which in turn were used for calculating the effective area of the piston gauge at various pressure points. From the obtained effective area with pressure values, the zero pressure effective area and the distortion coefficients were calculated. In addition, the results of FEA were also compared with the previously published results from the Monte Carlo Simulation on the same piston-cylinder assembly. Interestingly, the uncertainty associated with the distortion coefficient estimated using FEA, was found to be an order of magnitude lower as compared to the other approaches.

Tool wear induced modifications of plastic flow and deformed material depth in new generated surfaces during turning Ti-6Al-4V

The thermo-mechanical loads induced by tribological interfaces complicate the descriptions of the local plastic deformation behaviours in high-speed machining. This study utilized finite element simulation technique and microstructural observation to investigate the local plastic deformation behaviours of new generated chips and machined surface in turning Ti-6Al-4 V. The plastic deformation behaviours modifications of plastic flow and deformed material depth under different tool wear states were discussed. On one hand, the Arbitrary-Lagrangian-Eulerian (ALE) modelling based on hybrid sticking-sliding friction model was proposed with dependence of tool wear geometrical changes. The multi-physics variables distributions such as cutting temperature, strain, and strain rate were acquired to provide the basic analysis of thermo-mechanical loads induced by tribological effects. On other hand, the experimental evidences of local plastic deformation behaviours including intensive microstructural changes in primary/secondary/tertiary deformation zones were analysed in details. Both simulated and experimental results indicated that thermo-mechanical loads due to tool wear effects were the critical driving factor for local plastic behaviours evolution. The deformation strength of primary/secondary/tertiary zones increased because of the gradual increasing contact areas and heat generation. This study can help to control the microstructural evolutions by limiting tool wear and enhance the surface quality.

A new technology for steel pipeline damage detecting without removing cladding

• Harmonic signal generators is developed and harmonic magnetic field detection technology is proposed. • Magnetic focusing array detection probe is designed. • Inner and outer damage of in-service pipeline can be detected based on the proposed technology. In this study, a harmonic magnetic field detection technology is proposed in order to detect the damage of an in-service coated steel pipeline. Based on the electromagnetic theory and magnetic field detection principle integrated with magnetic focusing technology, an array consisting of focusing detection probe and harmonic magnetic field detection system was designed. Numerical simulations for different coil structures was performed by finite element simulation technique to explore the focusing performance of designed coil structure. The feasibility of the detection probe and harmonic magnetic field detection technology was verified by experimental results and numerical simulations. The results of this study show that the proposed method can provide excellent information about the full wall thickness by penetrating the cladding over the surface of pipeline and effectively identify the outer wall defects and the inner wall corrosion.

Finite element analysis and simulation study on micromachining of hybrid composite stacks using Micro Ultrasonic Machining process

Hybrid composites stacks are multi-material laminates which find extensive applications in industries such as aerospace, automobile, and electronics and so on. Most hybrid composites consist of multiple layers of fiber composites and metal sheets stacked together. These composite stacks have excellent physical and mechanical properties including high strength, high hardness, high stiffness, excellent fatigue resistance and low thermal expansion. Micromachining of these materials require particular attention as conventional methods such as micro-drilling is extremely challenging considering the non-homogeneous structure and anisotropic nature of the material layers. Micro Ultrasonic Machining (μUSM) is a manufacturing process capable of machining such difficult-to-machine materials with ultraprecision. Experimental study showed that μUSM process could successfully machine hybrid composite stacks at micron scale with a relatively good surface finish. This research uses finite element simulation technique to investigate the material removal during the μUSM process for micromachining hybrid composite stacks. The effects of critical process parameters including the amplitude of vibration, feed rate and tool material on the cavity depth, cutting force and equivalent stress distribution are studied. The outcome of this research can be utilized to further our understanding of performing precision machining of hybrid composite stacks for use in several critical engineering applications.