FEM Simulation Research Articles

Effect of natural crack distributions on coal failure process based on fluorescent epoxy impregnation method and phase-field FEM simulation

Effect of natural crack distributions on coal failure process based on fluorescent epoxy impregnation method and phase-field FEM simulation

Grain Size Distribution of DP 600 Steel Using Single-Pass Asymmetrical Wedge Test

Grain size distribution after the completion of a phase transformation was studied through the laboratory-controlled hot-plastic deformation of dual phase 600 (DP 600) steel using a specially prepared asymmetric single-pass hot-rolling wedge test with a refined reheating grain size instead of the usual coarse-grained starting microstructure observed in practice. The experiment was performed to reduce generally needed experimental trials to observe the microstructure development at elevated temperatures, where stable and unstable conditions could be observed as in the industrial hot-rolling practice. For this purpose, experimental stress–strain curves and softening behaviors were used concerning FEM simulations to reproduce in situ hot-rolling conditions to interpret the grain size distribution. The presented study revealed that the usual approach found in the literature for microstructure investigation and evolution with a hot-rolling wedge test was deficient concerning the observed field of interest. The degree of potential error concerning the implemented deformation per notch position, as well as the stress–strain rate and related mean flow stresses, were highly related to the geometry of the specimen and the material behavior itself, which could be defined by the actual hardening and softening kinetics (recrystallization and grain growth at elevated temperatures and longer interpass times). The grain size distribution at 1100–1070 °C was observed up to a 3.45 s−1 strain rate and, based on its stable forming behavior according to the FEM simulations and the optimal refined grain size, the optimal deformation was positioned between e = 0.2 and e = 0.5.

Investigation on anchor and base design for aluminum nitride flexural mode resonators

This paper investigates the impact of base and anchor on the quality factor (Q) of piezoelectric microelectromechanical system (MEMS) tuning fork resonators vibrating in in-plane flexural mode, and proposes a new strategy to improve Q significantly. Finite element method simulation and measured results reveal that base and anchor geometries have a significant impact on the thermoelastic damping (TED) which dominates the overall resonator quality factor. For the first time, we accurately extract Q value related to TED of piezoelectric tuning fork resonators by cryogenic temperature experiment, which is consistent with FEM simulation results. According to the analysis, a wider anchor or a longer base should promote overall Q by restraining the thermal conduction induced by TED. On the other hand, increase of width or length of anchor will force the out-of-plane flexural modes closer to the target mode, reducing the overall Q by multimode effect. With a wide anchor and a pillar structure under the base to suppress multimode effect, the resonator Q could be improved by 65% to more than 11 000 and impedance at series resonant frequency (f s) could be reduced by 78% to 6.5 kΩ. To our knowledge, the proposed resonator exhibits the highest f× Q and lowest motional impedance among the reported in-plane mode piezoelectric MEMS tuning fork resonators.

Why is aluminum‐based lithium adsorbent ineffective in Li+ extraction from sulfate‐type brines

AbstractAluminum‐based lithium adsorbent (Li/Al‐LDH) is the only industrialized adsorbent for Li+ extraction from salt lake brines. The inherent mechanism of declined Li+ adsorption performance was revealed to explain the feebleness in sulfate‐type brines. SO42− in brines could replace interlayer Cl− by a stronger electrostatic attraction with laminates, significantly altering the stacking structure and interlayer spacing, while Cl K‐edge of XAFS showed intercalated SO42− would not obviously change the chemical environment of interlayer Cl−. Experiments as well as DFT and FEM simulations indicated the intercalated SO42− regulated Li+ adsorption of Li/Al‐LDHs at different ionic strength under a combined effect of expanded interlayers, close packing, and electrostatic repulsion. Although sufficient SO42− contents in brines might promote the single Li+ adsorption by offering ionic strength as a driving force, the long‐term usability would be severely impaired as SO42− intercalation in interlayers reduced the subsequent Li+ adsorption capacity and increased the desorption difficulty.

The Drucker–Prager criterion-based plasticity theory of amorphous alloys under the complex stress states

The constitutive models of materials are pushed to their limits in a wide range of service scenarios, each with a unique stress state, strain rate, and temperature coupling. This paper successfully captured the stress state sensitivity of amorphous alloys using the free volume theory and the Drucker–Prager yield criterion. The varying yield surface and shear band angle as the dilation coefficient changes are well captured by the FEM simulations. The model can also accurately portray the influence of the stress state, as well as the difference of shear-induced dilation between the tension and compression. This model can facilitate the application of amorphous alloys in complicated local stress states at a large scale and structural level, such as in chiral mechanical metamaterials and gear structures.

FEM Simulation of Pulsed Laser Welding of High-Carbon Alloy Steel: Using Different Heat Source Models

FEM Simulation of Pulsed Laser Welding of High-Carbon Alloy Steel: Using Different Heat Source Models

Modelling and analysis of electromagnetic vibration in long sheet secondary tubular linear induction motors

AbstractThis paper aims to clarify the behaviour and mechanism of electromagnetic vibration in long sheet secondary tubular linear induction motors (LSS‐TLIMs). Firstly, the spatial and temporal characteristics of electromagnetic force acting in the stator are analysed. Secondly, based on the wave propagation method, an analytical model is established to calculate the vibration response of the stator, which is simplified as a finite cylindrical shell. The accuracy of the proposed model, as well as the rationality of the simplification, are verified by 3D FEM simulation. It is indicated that the electromagnetic vibration response of LSS‐TLIMs mainly depends on the “axial breathing mode” (ABM) and corresponding “modal participation factor”. Moreover, the influences of the spatial distribution of electromagnetic force and the structural dimensions on the vibration are investigated. Finally, the “static vibration test” is performed to validate the above analysis. It is concluded that, compared with a rotary motor, the low‐frequency vibration of LSS‐TLIMs can be easily controlled since the natural frequency of ABMs tends to be much higher than that of the circumferential mode.

FEM simulation of a novel medical device for TMJ therapy

Temporomandibular disorders (TMD) are one of the leading health problems in dentistry. The work aimed to evaluate, using FEM, the influence of the material elastic properties of the flexible obstacle of the tongue trainer on the range of deflection and strength.In prototyping the trainer tongue, the starting point was real models with different extents of the tongue obstacle. moulded from dental wax on a dental stone model. Then versions were tested intraorally for the perception of the space occupied by the tongue. The models were scanned on a 3D scanner, and then a parametric CAD model (NX Siemens) was made on their basis. Finally, in order to take into account, the anatomical aspects, the two extreme ranges of the tongue obstacle, named "Long " and " Short ", were developed. Simulation deflection and material strength tests were made using FEM in the linear range (NX Siemens). Calculations were made for materials with Young's modulus equal to 8 MPa, 80 MPa and 800 MPa. The interaction of the tongue with the force of 5N was assumed. The support was provided by the retention surface on the teeth, with the support of the posterior edge of the obstacle on the palate (palatal variant) or lack of support, i.e., the obstacle freely bending in this area (free variant), was additionally tested. In order to assess the drop or retention of the trainer on the teeth, the second type of simulation was performed with the assumption of horizontal (anteriorly directed) tongue pressure with the force of 10N for the condition of rigid support in the area of the teeth and the periodontal zone from the lingual side. In this variant, a simulation was adopted for a material with a modulus of elasticity E=80 MPa.The stress values of the flexible obstacle of the trainer were obtained, allowing for the selection of potentially valuable materials for the trainer's construction. The results obtained in the simulations indicate the possibility of using ethylene vinyl acetate (EVA) and its blends. The accumulation of saliva inside the sealed obstacle was found, which indicated the need to look for an area to perforate without losing the load capacity of the obstacle. The structural feasibility of solving the problem of saliva accumulation without a significant change in the load capacity and stiffness of the obstacle was confirmed by simulation.Simplifying the model to a linear range does not allow buckling analysis. In addition, the assumption of a linear material further limits the possibility of analysing materials with softening and plateau characteristics, where the compliance of the structure leads to elastic buckling.The range of deflections and stresses for different stiffness of the elastic element of the trainer was determined in order to select the appropriate material for the medical device (MD). Polyurethanes or silicones provide the range of deflection and strength, but in the case of manufacturing prefabricated trainers thermoformed in the patient's mouth (maximum temperature 75C), the material that can be used is ethylene vinyl acetate (EVA).Simulation tests made it possible to determine the range of deflections and stress for different stiffness of the flexible obstacle of the trainer in order to select the appropriate material for the medical device.

Failure analysis on wave compensator and hull structure of trailing suction hopper dredger (TSHD) under Medium-Long period wave

In the process of dredging construction, the trailing suction dredger (TSHD) in the medium-long period waves usually encounters a violent 6-DOF (six degree of freedom) motion. It may lead to the failure of the wave compensator beyond its stroke, and also the failure of structural strength due to the impact of drag arm. Based on the CFD method, the motion simulation of a 10000 m3 TSHD under medium-long period waves is carried out, the most violent condition is found as wave height of 3.5 m, period of 12 s, and direction of 90°, with the peak values of roll and heave are 10.84° and 1.18 m. For TSHD under dredging state, the stress on hull and drag arm is calculated. FEM simulation is used to analyze the structural dynamic response and strength failure of the hull structure in collision with drag arm. Finally, the impact of wave conditions on the collision between drag arm and hull is summarized, and the basic safe wave conditions for the failure of the drag arm, hull, and wave compensator are determined to guide the construction safety of TSHD.

FEM-GAN: A Physics-Supervised Deep Learning Generative Model for Elastic Porous Materials.

X-ray μCT imaging is a common technique that is used to gain access to the full-field characterization of materials. Nevertheless, the process can be expensive and time-consuming, thus limiting image availability. A number of existing generative models can assist in mitigating this limitation, but they often lack a sound physical basis. This work presents a physics-supervised generative adversarial networks (GANs) model and applies it to the generation of X-ray μCT images. FEM simulations provide physical information in the form of elastic coefficients. Negative X-ray μCT images of a Hostun sand were used as the target material. During training, image batches were evaluated with nonparametric statistics to provide posterior metrics. A variety of loss functions and FEM evaluation frequencies were tested in a parametric study. The results show, that in several test scenarios, FEM-GANs-generated images proved to be better than the reference images for most of the elasticity coefficients. Although the model failed at perfectly reproducing the three out-of-axis coefficients in most cases, the model showed a net improvement with respect to the GANs reference. The generated images can be used in data augmentation, the calibration of image analysis tools, filling incomplete X-ray μCT images, and generating microscale variability in multiscale applications.

FEM Simulation of AlSi10Mg Artifact for Additive Manufacturing Process Calibration with Industrial-Computed Tomography Validation.

Dimensional accuracy of selective laser melting (SLM) parts is one of manufacturers' major concerns. The additive manufacturing (AM) process is characterized by high-temperature gradients, consolidation, and thermal expansion, which induce residual stress on the part. These stresses are released by separating the part from the baseplate, leading to plastic deformation. Thermo-mechanical finite elements (FE) simulation can be adopted to determine the effect of process parameters on final geometrical accuracy and minimize non-compliant parts. In this research, a geometry for process parameter calibration is presented. The part has been manufactured and then analyzed with industrial computed tomography (iCT). An FE process simulation has been performed considering material removal during base plate separation, and the computed distortions have been compared with the results of the iCT, revealing good accordance between the final product and its digital twin.

Optimization of the First-Step Drawing Parameters for Platinum-Clad Nickel Bar Based on FEM Simulation

The first-step drawing process of the platinum-clad nickel composite bar was numerically simulated using DEFORM 3D finite element analysis software. The Taguchi method was used to study the effect of the first-step drawing parameters (the semi-angle of die α, the friction coefficient between the platinum tube and die μ1, the friction coefficient between the platinum tube and nickel rod μ2 and the outer diameter of the original platinum tube D) on the effective stress of platinum-clad nickel bar. Then, the optimal combination of parameters (D = 7.55 mm, μ1 = 0.2, μ2 = 0.3, α = 3°) was obtained. Furthermore, the results of the deformation behavior, cladding behavior, stress effectiveness and the distribution of the damage of the composite bar using optimization schemes were compared and analyzed with Numerical Simulations 8, which showed the worst result. Meanwhile, the experimental results were in general agreement with the simulation results of optimal combination of parameters, indicating that our simulation results are plausible. This has certain guidance significance to improve the quality of platinum-clad nickel composite wires in actual production.

Assessment of AC Corrosion Probability in Buried Pipelines with a FEM-Assisted Stochastic Approach

In this paper, a stochastic approach is combined with field theory and circuit methods to study how the geometrical and electrical properties of holidays (defects or pores in the insulating coating) in a metallic pipeline influence the probability of exceeding the current density limit for corrosion. Three-dimensional FEM simulations are conducted to assess the influence of the shape and electrical resistivity of the pore on the computed spread resistance value. The obtained results are then used to evaluate the probability of exceeding a given current density value for different sizes of pore and soil resistivities. Finally, a case of 50 Hz interference along a pipeline-transmission line routing is examined. The probabilistic approach presented in this paper allows the pipeline sections more subjected to the induced AC corrosion risk to be identified to be used as an auxiliary tool for adopting preventive protection countermeasures. Lastly, unlike most papers devoted to assessing electromagnetic interference on pipelines, the present work uses a probabilistic rather than a deterministic approach, representing its main novelty aspect.

Fem Simulation of Connecting Rod for Minimal Distortion using Aluminum Alloy- A Review

The connecting rod is a critical component in internal combustion engines, transmitting the reciprocating motion of the piston to the crankshaft. The structural integrity and performance of the connecting rod are essential for the overall efficiency and reliability of the engine. Aluminum alloys are commonly used in connecting rod manufacturing due to their desirable properties such as high strength-to-weight ratio and excellent machinability. However, during the manufacturing process, connecting rods made of aluminum alloys are susceptible to distortion, which can adversely affect their performance. Finite element method (FEM) simulation has emerged as a powerful tool for analysing the mechanical behaviour of complex structures, including connecting rods. This review paper aims to present an overview of recent research and developments in FEM simulations of connecting rods made from aluminum alloys, with a focus on minimizing distortion during manufacturing processes The review begins with an introduction to the importance of connecting rods and the challenges associated with distortion during manufacturing. It then provides an overview of the FEM methodology, including the modelling techniques, material models, and boundary conditions commonly employed in connecting rod simulations.

Realization of a Test Tool for Diagnosis of Contact Resistance and Measurement of Selected Types of Conductive Materials

Contact connections in electrical machines and apparatus are important elements in the whole power supply network and a high level of reliability is expected there. Contact resistance is a fundamental criterion in the design of an electrical contact or contact system. The contact resistance should be as low as possible to minimize losses due to the current passage and the related heating of the contact connection. The value of the contact resistance depends on the material used, the value of the applied force, the type of contact, and, last but not least, the quality of the surface and chemical layers. In this paper, an initial diagnosis of the contact material is performed based on the determination of the sample’s specific resistivity by the four-wire method and the evaluation of the measurement uncertainty. The work is followed by the design of a testing device that uses crossed bars to measure the change in contact resistance as a function of the magnitude of the applied force. An analysis of the sample mounting method is performed here using FEM simulations of the current field and shows the interaction between the holder and the sample in terms of current line transfer. The proposed system is then used for experimental measurements of the material-dependent coefficient KC for verification of existing or newly developed materials in electrical engineering, where the values of the KC coefficient are not known. Finally, the paper also deals with the measurement of fritting voltage for individual contact pairs having surface quality corresponding to brushing.

Modeling and computer heat analysis of the proposed sample for testing hardenability of steel as a simplification of Grossman methods

The article presents a calculation model of the proposed sample to test the hardenability of steel to replace a series of samples - one. Previous studies have not included this type of sample shape. The FEM simulation of the sample was also compared with that of a cylindrical cross-sectional sample. The calculations made it possible to verify the initial assumption and provided new opportunities to develop a simplification of real steel hardenability tests of steel. Test results may also allow for the simplification of the designed structure. The work also includes perspectives on the development of the method

Investigation of Underpass and Railway Track Settlements Induced by Shield Tunneling Through In Situ Test and 3D FEM Simulation

Investigation of Underpass and Railway Track Settlements Induced by Shield Tunneling Through In Situ Test and 3D FEM Simulation

INVESTIGATION USING FINITE ELEMENT ANALYSIS OF EFFECT TO EARRING OF ANISOTROPY PARAMETERS IN DEEP DRAWING PROCESS

The investigation mentioned focuses on utilizing finite element analysis to study the impact of anisotropy parameters on the behavior of earrings during the deep drawing process. deep drawing is a manufacturing technique used to transform flat sheet metal into three-dimensional shapes, and anisotropy refers to the directional dependence of material properties. by analyzing and understanding how anisotropy parameters affect the behavior of earrings during the deep drawing process, this investigation aims to provide valuable insights for optimizing the manufacturing process and enhancing the quality and durability of earrings. In this study, an Al6061-T6 sheet material with different planar anisotropies with a single thickness of 2 mm was employed to simulate the effects of anisotropy parameters on the earring by using finite element method. The effects of anisotropy parameters on the earring were examined by using FEM. Variations force obtained in Δr_2 are higher than Δr_1. This is due to the anisotropy of the material. It can be said that the FEM simulations give reasonable results in view of earring for deep drawing processes. So, experimental costs can therefore be avoided using a suitable FEM model.

Damage sensitivity studies of composite honeycomb sandwich structures under in-plane compression and 4-point bending: Experiments and numerical simulations

Honeycomb sandwich structures, especially those with carbon-fiber panels and Nomex-honeycomb cores, are widely employed in automobiles and aircraft due to their excellent mechanical properties. Here, in-plane compression and 4-point bending experiments, as well as FEM simulations, are performed for a composite honeycomb sandwich structure with face-core de-bonding defects or impact damage to evaluate the damage sensitivity. It is found that the structure exhibits a higher sensitivity to impact damage than to de-bonding defects. Impact damage caused by an energy of 3 J–5.5 J can alter the failure mode under both in-plane compression and 4-point bending loads, and reduce in-plane compression strength by more than 50 % and 4-point bending strength by 15 %. In comparison, de-bonding defects of the same size can change the failure mode and decrease the strength by only 10 % under in-plane compression. The developed FEM model predicts all failure modes and residual strengths obtained from experiments. The simulation results show that the structural characteristics of producing concaves in the facesheet and core are the dominant contributors to structural failure. Our model, covering all geometric and structural details of the honeycomb core, provides a useful tool for studying the mechanical behaviors of such structures.

Crack-Based Sensor with Microstructures for Strain and Pressure Sensing

Recent extensive research on flexible electronics has led to the development of various flexible sensors. In particular, sensors inspired by the slit organs of a spider, which utilize cracks in a metal film to measure strain, have garnered considerable interest. This method exhibited significantly high sensitivity, repeatability, and durability in measuring strain. In this study, a thin-film crack sensor was developed using a microstructure. The results exhibited its ability to simultaneously measure the tensile force and pressure in a thin film, further expanding its applications. Furthermore, the strain and pressure characteristics of the sensor were measured and analyzed using an FEM simulation. The proposed method is expected to contribute to the future development of wearable sensors and artificial electronic skin research.