Finite Element Analysis Methodology Research Articles

Performance Analysis of Magnetorheological Damper with Folded Resistance Gaps and Bending Magnetic Circuit

The traditional magnetorheological (MR) damper subject to the limited space has shortcomings such as small damping force, narrow dynamic range and low adaptability. In this study, a new MR damper with folded resistance gaps and bending magnetic circuit was proposed for improving the damping performance. The length of the resistance gap was increased by configuring the multi-stage folded annular gap structure, and the magnetic circuit was established to activate the non-flux region. The mathematical model was established for the MR damper to analyze the damper force, magnetic circuit and dynamic performance. Subsequently, the finite element analysis (FEA) methodology was utilized to investigate the changes of magnetic flux densities in the folded resistance gaps. The test rig was setup to explore and verify the dynamic performance of the proposed MR damper under different excitation conditions. The results indicate the maximum damping force is approximately 4346 N at the current of 1.5 A, frequency of 0.25 Hz and amplitude of 7.5 mm. The damping force and dynamic range of the proposed MR damper are enhanced by 55.82% and 62.21% compared to that of the traditional MR damper at the applied current of 1.5 A, respectively, thus highlighting its high vibration control ability.

Minimum thickness of solid concrete floor slab with column line beams to avoid walking vibration discomfort

AbstractIn this study, an attempt has been made to evaluate the minimum slab thickness of reinforced concrete (RC) solid floor slab with column‐line beams to minimize vibration discomfort when subjected to human walking‐induced excitation. An elastic time history finite element analysis methodology has been adopted for the study. An intermediate floor panel of a multistory building has been modeled using appropriate material properties, element dimensioning and stiffness modifiers. The developed model was subjected to a walking excitation using a time history function. The finite element modeling and time history analysis scheme has been validated against experimental study described in the design guide by Fanella and Mota. The study was then focused on studying the walking‐induced vibration characteristics of the floor slab using the span length and slab thickness as the study parameters. The acceleration data obtained for the central point of the slab was subjected to fast fourier transform (FFT) to convert the response to the frequency domain. Comparisons were then made to obtain the minimum slab thickness for each span length using both frequency and acceleration criteria following ACI serviceability limit and the design guide limit by Fanella and Mota. It was observed that a combination of the two limits were needed to determine the minimum slab thickness. The findings will help engineers to design slabs with adequate thickness to minimize human walking‐induced vibration related discomfort.

A Finite Element Analysis and Circuit Modelling Methodology for Studying Electrical Impedance Myography of Human Limbs.

Electrical impedance myography (EIM) measures bioimpedance over muscles. This paper proposes a circuit-based modelling methodology originated from finite element analysis (FEA), to emulate tissues and effects from anthropometric variations, and electrode placements, on EIM measurements. The proposed methodology is demonstrated on the upper arms and lower legs. FEA evaluates impedance spectra (Z-parameters), sensitivity, and volume impedance density for variations of subcutaneous fat thickness (t f), muscle thickness (t m), and inter-electrode distance (IED), on limb models over 1Hz-1 MHz frequency range. The limbs' models are based on simplified anatomical data and dielectric properties from published sources. Contributions of tissues to the total impedance are computed from impedance sensitivity and density. FEA Z-parameters are imported into a circuit design environment, and used to develop a three Cole dispersion circuit-based model. FEA and circuit model simulation results are compared with measurements on ten human subjects. Muscle contributions are maximized at 31.25 kHz and 62.5 kHz for the upper arm and lower leg, respectively, at 4 cm IED. The circuit model emulates variations in t f and t m, and simulates up to 89 times faster than FEA. The circuit model matches subjects measurements with RMS errors and , while FEA does with and . We demonstrate that FEA is able to estimate the optimal frequencies and electrode placements, and circuit-based modelling can accurately emulate the limbs' bioimpedance. The proposed methodology facilitates studying the impact of biophysical principles on EIM, enabling the development of future EIM acquisition systems.

Cutting force & thermal analysis during turning using Ansys

In metal cutting, the magnitude of the cutting forces and temperature at various interfaces is the function of the cutting process variables. These cutting process variables directly affect production. Therefore, more research on this topic and further development will lead to improved production. Experimental work was conducted under dry machining with heat-treated 4140 Alloy Steel workpiece and the cutting tool was Cast Steel Silver Brazed Carbide were used under turning process. In this experimentation, during the machining the cutting forces were measured using Tool-Lathe Sharp Techno Dynamometer and the temperature measurement was done employing two techniques that were K-Type Thermocouple for the tool temperature and Infrared Thermometer for the tool chip contact area temperature. In this research, Finite Element Analysis (FEA) methodology was used, with cutting forces and temperatures at the different points of the cutting tool as an input. Model of the Single Point Cutting Tool (SPCT) was generated using Solid Works software and the analysis was done in Ansys (Workbench) software. The Ansys software analyzed the Single Point Cutting Tool (SPCT) model by FEA and results obtained are discussed in this study.

Heat transfer simulation in laser irradiated retinal tissues

A realistic model of human retinal tissues to simulate thermal performance of optical laser photocoagulation therapy is presented. The key criteria to validate the treatment effectiveness is to ensure the photocoagulation temperature between 60 and 70 °C is reached in the treatment region of interest. The model presented consists of truncated volumes of the retinal pigment epithelium (RPE) and adjacent retinal tissues. Two cases of choroid pigmentation are modelled to signify extreme cases of human eye difference: albino and dark colour choroid pigmentation. Conditions for consistent heating over the irradiated treatment spot is modelled for laser beams with different intensity profiles: ‘top-hat’, Gaussian and ‘donut’ modes. The simulation considers both uniform heating within retinal tissue layers and spatial intensity decay due to absorption along the direction of laser propagation. For a 500 μm spot, pulse length 100 ms and incident power to the cornea of 200 mW, realistic spatial variation in heating results in peak temperatures increasing within the RPE and shifting towards the choroid in the case of choroidal pigmentation. Finite element analysis methodology, where heat transfer theory governs the temperature evolution throughout tissues peripheral to the irradiated RPE is used to determine the zone of therapeutic benefit. While a TEM01 donut mode beam produces lower peak temperatures in the RPE for a given incident laser power, it reduces the volume of retinal tissue reaching excessive temperatures and maximises the zone of therapeutic benefit. Described are simulation limitations, boundary conditions, grid size and mesh growth factor required for realistic simulation.

Finite element analysis of fracture behavior in ceramics: Prediction of strength distribution using microstructural features

AbstractThe estimation of the strength scatter caused by internal defects is necessary in analyzing a reliable design of advanced ceramic components. In this study, we proposed a finite element analysis methodology to predict the stochastic fracture behavior of ceramics based on the microstructural features obtained by the scanning electron microscopy and X‐ray computed tomography. Here, the two‐ and three‐dimensional distribution microstructural data are approximated by various probability density functions and are reflected in the dispersion of parameters of the damage model via a fracture mechanics model. We then applied the proposed method to alumina fine ceramics sintered at three different temperatures, and performed the three‐point bending test. Furthermore, the numerically created Weibull distributions were compared with those obtained experimentally. Our analysis results confirm that the proposed method can reasonably predict the strength scatter in ceramics.

A study on finite element analysis methodologies and approaches used for total hip arthroplasty

The continuously increasing necessities of total hip arthroplasty (THA) and revision hip arthroplasty (RHA) due to the worldwide increasing aging population and increased accident rates have caught the attention of researchers for improving the biological and mechanical performances of transplanted hip implants. There has been an excessive amount of research works in this context in the last few decades using finite element analysis (FEA). This review article aimed to identify the major criteria and approaches that FEA can implement so that superior performances from hip implants can be obtained. The study revealed some important areas and approaches such as geometrical design, topology optimization, utilization of beneficial materials, functional grading of materials (FGM), and helpful coating layers that can be optimized for improving the performances of hip implants. Furthermore, the study focused on defining suspected failure regions and the role of fixation devices in reducing the failure of the hip implant prosthesis.

Numerical Analysis of Plastic Strain Inhomogeneity in Rectangular Vortex Extrusion (RVE) Process

In this study, the effect of geometrical parameters of rectangular vortex extrusion die, including twist angle (Φ), reduction in area (RA), and twist zone length (L), on deformation inhomogeneity is investigated using the finite element analysis and response surface methodology. Analysis of variance (ANOVA) was used to determine the primary parameters and accuracy of the mathematical model obtained from response surface methodology results. The results showed that the suggested mathematical model predicts the strain inhomogeneity with high accuracy. Additionally, it revealed that the input parameters of Φ, RA, L, the interaction between Φ and RA (Φ×RA), and interaction between RA and L (RA×L) are the main significant factors affecting the inhomogeneity. Perturbation plots and 3D surface diagrams were used to check the results of ANOVA, the sign, and the magnitude of the coefficient of the suggested mathematical model. RA

Dynamic analysis of the plate on multi-elastic-layer foundation under moving load

The dynamic respones of the plate under moving load is an open problem, it has been researched, developed in many majors of solidmechanics, particularly in transport construction. This article presents a methodology of finite element analysis and a solution of thepartial differential equation for the structure of the Kirchhoff plate on the multi-elastic-layer foundation bearing moving load. In which,the multi-elastic-layer foundation is described as the homogeneous Winkler foundation. The moving load with mass oscillates togetherwith the plate. The surveys have been studied in order to show the effects of parameters of foundation and load to the oscillation of the plate.

Novel Finite Element Analysis of Curved Concrete Box Girders Using Hybrid Box Elements

Horizontally curved concrete bridges are widely used in urban viaducts and overpasses all over the world. A box cross-section is often used in curved concrete girders because of its high resistance to both bending and torsion. This study focuses on the development of a new finite element analysis (FEA) methodology incorporating a novel formulation for curved box sections using orthotropic constitutive models for reinforced concrete, along with a layered shell theory approach. In the new approach, the box section is treated as a frame consisting of curved shell elements modeling webs and flanges and curved beam elements in the web-flange junctions. The use of shell and beam elements in the formulation significantly reduces the number of elements needed to model the box-section girder while maintaining the accuracy of the model. A degenerate superparametric shell element with reduced integration is used to avoid shear-locking, membrane-locking, and zero-energy problems. Prestrain effects are considered in the formulation to account for prestressing forces. The simulation results are compared to the available experimental results on four straight and curved, reinforced and prestressed, concrete box-section girders, with good agreement in terms of the deflections, twist angles, and strains in the prestressed reinforcement. Some critical issues in the analysis of concrete box girders, such as postpeak-strength behaviors, distortion of box section, are also discussed.

Stress and coupled electromagnetic-thermal analysis of field excited flux switching machine

Purpose Field excited flux switching machines (FEFSM) are preferred over induction and synchronous machines due to the confinement of all excitation sources on the stator leaving a robust rotor. This paper aims to perform coupled electromagnetic thermal analysis and stress analysis for single phase FEFSM as, prolonged high-speed operational time with core and copper losses makes it prone to stress and thermal constraints as temperature rise in machine lead to degraded electromagnetic performance whereas the violation of the principle stress limit may result in mechanical deformation of the rotor. Design/methodology/approach This paper presents the implementation of coupled electromagnetic-thermal and rotor stress analysis on single-phase FEFSM with non-overlap winding configurations using finite element analysis (FEA) methodology in JMAG V. 18.1. three-dimensional (3D) magnetic loss analysis is performed and extended to 3D thermal analysis to predict temperature distribution on various parts of the machine whereas Stress analysis predicts mechanical stress acting upon edges and faces of the rotor. Findings Analysis reveals that temperature distribution and rotor stress on the machine is within acceptable limits. A maximum temperature rise of 37.7°C was noticed at armature and field windings, temperature distribution in stator near pole proximity was 35°C whereas no significant change in rotor temperature was noticed. Furthermore, principal stress at the speed of 3,000 rpm and 30,000 rpm was found out to be 0.0305 MPa 3.045 MPa, respectively. Research limitations/implications The designed machine will be optimized for improvement of electromagnetic performance followed by hardware implementation and experimental testing in the future. Practical implications The model is developed for axial fan applications. Originality/value Thermal analysis is not being implemented on FEFSM for axial fan applications which is an important analysis to ensure the electromagnetic performance of the machine.

Tearing defect maps for the deep drawing of AISI 304 rectangular cups

Abstract This study proposes a method for integrating finite element analysis and response surface methodology to predict tearing locations in the deep drawing of a rectangular-shape AISI 304 cup. The finite element model was confirmed by a deep-drawing experiment with nitrogengas springs, and the finite element analysis results were in agreement. Moreover, the regression model was developed using response surface methodology to predict final thickness at various locations on the rectangular-shape deep-drawn cup based on 40 finite element cases containing varied blank holder forces. The maximum percentage of thinning values was obtained from the response surface methodology results. The relationships among the blank holder forces and the thinning values at different locations were then further developed. The maps of the predicted tearing locations were then obtained and directly corresponded to the number of locations the specific blank holder forces. These maps, as established, could be directly used in a closed-loop control system enabling tearing defects to be prevented or eliminated.

Interior Permanent Magnet Synchronous Motor Design for Eddy Current Loss Reduction in Permanent Magnets to Prevent Irreversible Demagnetization

We designed and analyzed an interior permanent magnet synchronous motor (IPMSM) to prevent irreversible demagnetization of the permanent magnets (PMs). Irreversible demagnetization of NdFeB PMs mainly occurs due to high temperature, which should thus be minimized. Therefore, it is necessary to reduce the eddy current loss in the PM through optimal design. The shape of the rotor core was optimized using finite element analysis (FEA) and response surface methodology. Three-dimensional (3-D) FEA is required for accurate computation of the eddy current loss, but there is huge time, effort, and cost consumption. Therefore, a method is proposed for indirectly calculating the eddy current loss of PMs using 2-D FEA. A thermal equivalent circuit analysis was used to calculate the PM temperature of the optimized model. For the thermal analysis, the copper loss, core loss, and eddy current loss in PMs were estimated and applied as a heat source. Based on the results, we confirmed the stability of the optimum model in terms of the PM demagnetization.

Cement augmentation of calcar screws may provide the greatest reduction in predicted screw cut-out risk for proximal humerus plating based on validated parametric computational modelling: Augmenting proximal humerus fracture plating.

AimsFixation of osteoporotic proximal humerus fractures remains challenging even with state-of-the-art locking plates. Despite the demonstrated biomechanical benefit of screw tip augmentation with bone cement, the clinical findings have remained unclear, potentially as the optimal augmentation combinations are unknown. The aim of this study was to systematically evaluate the biomechanical benefits of the augmentation options in a humeral locking plate using finite element analysis (FEA).MethodsA total of 64 cement augmentation configurations were analyzed using six screws of a locking plate to virtually fix unstable three-part fractures in 24 low-density proximal humerus models under three physiological loading cases (4,608 simulations). The biomechanical benefit of augmentation was evaluated through an established FEA methodology using the average peri-screw bone strain as a validated predictor of cyclic cut-out failure.ResultsThe biomechanical benefit was already significant with a single cemented screw and increased with the number of augmented screws, but the configuration was highly influential. The best two-screw (mean 23%, SD 3% reduction) and the worst four-screw (mean 22%, SD 5%) combinations performed similarly. The largest benefits were achieved with augmenting screws purchasing into the calcar and having posteriorly located tips. Local bone mineral density was not directly related to the improvement.ConclusionThe number and configuration of cemented screws strongly determined how augmentation can alleviate the predicted risk of cut-out failure. Screws purchasing in the calcar and posterior humeral head regions may be prioritized. Although requiring clinical corroborations, these findings may explain the controversial results of previous clinical studies not controlling the choices of screw augmentation.

Computed Tomographic Evaluation of the Sacroiliac Joints of Young Working Labrador Retrievers of Various Work Status Groups: Detected Lesions Vary Among the Different Groups and Finite Element Analyses of the Static Pelvis Yields Repeatable Measures of Sacroiliac Ligament Joint Strain.

Musculoskeletal injuries can lead to a working dog being withdrawn from service prior to retirement. During training exercises, young working dogs are often required to perform repetitive tasks, including adoption of an upright posture (or “hupp” task). Non-invasive, quantitative methods would be helpful for supporting research on effects of these repetitive tasks on sacroiliac joints (SIJ). Furthering our understanding of lesions in and biomechanical stresses on the SIJ could provide insight into possible training modifications for minimizing risks of SIJ injury. Aims of this retrospective, secondary analysis, exploratory study were to test hypotheses that (1) mean numbers of SIJ computed tomographic (CT) lesions/dog would differ among work status groups in young working Labrador Retrievers; (2) a methodology for using CT data and finite element analysis (FEA) to quantify SIJ ligament strain in the static canine pelvis would be feasible; and (3) this FEA methodology would yield repeatable measures of SIJ ligament strain. Clinical and CT data for 22 Labrador retriever working dogs, aged 11–48 months, were retrospectively reviewed. Dogs were categorized into three work status groups (Breeder, Detection, Other). A veterinary radiologist who was unaware of dog group status recorded numbers of CT lesions for each SIJ, based on previously published criteria. Mean numbers of SIJ CT lesions/dog were compared among dog work status groups. An a priori FEA model was created from the CT images of one of the dogs using image analysis software packages. Using tissue properties previously published for the human pelvis, various directional loads (n = 8) and forces (48 ligament strain values) were placed on the canine model in five trials. Repeatability was tested using regression analysis. There was a significantly greater mean number of subchondral sclerosis lesions in left SIJ of Breeder vs. Detection dogs, a significantly greater mean number of subchondral cysts in right SIJ for Detection vs. Breeder dogs, and a significantly greater mean number of subchondral cysts in right SIJ of Other vs. Breeder dogs (p < 0.05). Finite element modeling and analysis using CT data was feasible and yielded repeatable results in 47/48 (98%) of tests at each combination of strain, ligament, and side.

Optimization of Halbach magnetic roller for eddy current separation based on the response surface method and multi-objective genetic algorithm

Performance optimization of the magnetic roller of eddy current separator is an issue of great significance in the recycling industry. In this study, the Halbach array is proposed for the first time to be used in the eddy current separator. And the new concepts of area field intensity and magnet efficiency density are proposed to quantitatively evaluate the magnetic field intensity around the magnetic roller surface and the utilization efficiency of the magnet respectively. Then the effects of various structural parameters of the Halbach magnetic roller on the area field intensity and magnet efficiency density were systematically investigated by employing finite element analysis and response surface methodology. The results showed that the regression models of the area field intensity (R2=0.9846, Pred.R2=0.9420) and magnet efficiency density (R2=0.9946, Pred.R2=0.9782) are extremely significant and have good prediction capability. The magnetic roller can form a stronger magnetic field by selecting a larger magnetic block, and the utilization efficiency of the magnet is higher when the magnetic block’s shape tends to be flat or has larger curvature. Furthermore, a multi-objective optimization model with the area field intensity, magnet efficiency density, and magnetic pole number is established, and a multi-objective genetic algorithm is applied to get the optimal combinations of various structural parameters. It was found that the points of the Pareto-optimal solution are concentrated on a spatial surface, which reflects the trade-off relationship among the three objectives. It also shows that the performance parameters of many Pareto-optimal solutions are superior to that of previous studies and the eddy current separators found in the vicinity. The proposed method framework and the results are useful for the design and optimization of the magnetic roller, which will improve the separation efficiency of eddy current separation.

Tearing defect maps for the deep drawing of AISI 304 rectangular cups

Abstract This study proposes a method for integrating finite element analysis and response surface methodology to predict tearing locations in the deep drawing of a rectangular-shape AISI 304 cup. The finite element model was confirmed by a deep-drawing experiment with nitrogengas springs, and the finite element analysis results were in agreement. Moreover, the regression model was developed using response surface methodology to predict final thickness at various locations on the rectangular-shape deep-drawn cup based on 40 finite element cases containing varied blank holder forces. The maximum percentage of thinning values was obtained from the response surface methodology results. The relationships among the blank holder forces and the thinning values at different locations were then further developed. The maps of the predicted tearing locations were then obtained and directly corresponded to the number of locations the specific blank holder forces. These maps, as established, could be directly used in a closed-loop control system enabling tearing defects to be prevented or eliminated.

Determination of Residual Stresses in Ceramic-Metal Brazed Joint using Finite Element Analysis (FEA) and Experimental Validation of the Results

Ceramic vacuum feedthroughs are an inevitable requirement for any vacuum system which requires electrical feedlines to be inserted into the vacuum environment. These feedthroughs consist of metal-ceramic-metal transition and, therefore, require the brazing process as a joining technique. This process allows joining two base materials, i.e., Alumina and Kovar, for this case, which manifests different thermo-mechanical response. The difference between the coefficient of thermal expansion (CTE) of these materials causes the development of residual stresses during the cooling phase of the brazing process. Such residual stresses, if not addressed properly, can lead to the failure in the brazed joint even before the design limits. The purpose of this study is to assess these stresses by performing the thermo-mechanical analysis of the brazing process of ceramic-metal assembly through finite element analysis (FEA) technique. This study includes the assessment of non-linear behavior (due to temperature-dependent material properties) of Alumina and Kovar assembly. Further, X-ray diffraction (XRD) based residual stress measurement technique has been utilized to validate the FEA results. The paper shall present the FEA methodology (model, boundary condition, and results) followed by the experimental results and their comparison.

On the prediction of the bi-axial failure envelope of a UD CFRP composite lamina using computational micromechanics: Effect of microscale parameters on macroscale stress–strain behavior

A computational micromechanics based Finite Element (FE) analysis methodology is presented to predict the bi-axial failure envelope of a unidirectional (UD) carbon-epoxy composite ply. In order to estimate the effect of various microscale parameters that are influencing the macroscopic stress–strain behavior, under individual load cases, detailed numerical studies are conducted using a 3D RVE (Representative Volume Element) model. The constituent epoxy matrix plastic deformation in the RVE is captured using the linear Drucker-Prager plasticity model.The effect of the fiber–matrix interface damage, followed by frictional sliding of the constituent materials on the computed interface tractions is captured using the cohesive zone damage model combined with the Coulomb friction law, which is implemented into Abaqus using VUMAT. From the detailed FE analysis of the RVE under individual load cases, it is observed that the predicted macroscopic stress–strain behavior is sensitive to the fiber–matrix interface properties as well as the in-situ epoxy stress–strain behavior. Hence, using a coupled experimental-computational micromechanics approach the interface and the in-situ epoxy material properties are calibrated and validated. Using the calibrated interface and in-situ epoxy material properties, the bi-axial (transverse tension/transverse compression – in-plane shear) failure envelope of a UD composite ply is estimated. Comparing the predicted damage profiles and the failure envelope with the experimental results leads to good agreement and validates the proposed numerical methodology.

Effect of Processing Parameters on the Strain Inhomogeneity and Processing Load in Vortex Extrusion of Al–Mg–Si Alloy

Vortex extrusion (VE), a single pass severe plastic deformation technique, can impose a high amount of effective strain obtained from simultaneously twisting and reduction in area on the processed material. In this study, a hybrid investigation based on finite element analysis (FEA) and response surface methodology (RSM) was carried out to investigate the effect of geometrical parameters involved in VE die design on the strain inhomogeneity and processing load in vortex extrusion of Al–Mg–Si alloy. The analysis of variance (ANOVA) was used for verifying the effect of input variables and the significance of mathematical modeling. Developed mathematical model from RSM was verified using results obtained from the experiment. Results showed that increasing the twist angle increases the effective strain inhomogeneity. Twist angle ( $$\varphi$$ ), reduction in area (RA), and interaction of twist angle and reduction in area ( $$\varphi \times RA$$ ) were determined as the most effective parameters affecting strain inhomogeneity, while the processing parameters of $$\varphi$$ , RA, and the interactions of $$\varphi \times RA$$ , $$\varphi \times \varphi$$ and $$RA\times RA$$ are the most effective parameters on the load of VE process.