Search

Aortic dissection is a life-threatening disease that consists in the development of a tear in the wall of the aorta. The initial tear propagates as a discontinuity leading to separation within the aortic wall, which can result in the creation of a so-called false lumen. A fatal threat occurs if the rupture extends through the whole thickness of the aortic wall, as blood may then leak. It is generally accepted that the dissection, which can sometime extend along the entire length of the aorta, propagates via a delamination mechanism. The aim of the present paper is to provide experimentally validated parameters of a mathematical model for the description of the wall's cohesion. A model of the peeling experiment was built in Abaqus. The delamination interface was described by a piecewise linear traction-separation law. The bulk behavior of the aorta was assumed to be nonlinearly elastic, anisotropic, and incompressible. Our simulations resulted in estimates of the material parameters for the traction-separation law of the human descending thoracic aorta, which were obtained by minimizing the differences between the FEM predictions and the delamination force given by the regression of the peeling experiments. The results show that the stress at damage initiation, Tc, should be understood as an age-dependent quantity, and under the assumptions of our model this dependence can be expressed by linear regression as Tc = − 13.03·10−4·Age + 0.2485 if the crack front advances in the axial direction, and Tc = − 7.58·10−4·Age + 0.1897 if the crack front advances in the direction of the aortic circumference (Tc [MPa], Age [years]). Other model parameters were the stiffness K and the separation at failure, δf–δc (K = 0.5 MPa/mm, δf–δc = 0.1 mm). The material parameters provided by our study can be used in numerical simulations of the biomechanics of dissection propagation through the aorta especially when age-associated phenomena are studied. [ABSTRACT FROM AUTHOR]

Numerical simulations are essential for predicting the mechanical properties of different structures like gyroids that center this study. Three different methods are explored: shell elements, solid elements, and homogenization. Results reveal that homogenization is only suitable for obtaining the properties in the elastic zone, whereas solid models can determine also the behaviors in the plateau zone and the densification point. In the case of shell elements model, it can predict the elastic behavior model and the levels of stress in the plateau zone but with a lower accuracy than the solid element, but it cannot predict the densification point. [ABSTRACT FROM AUTHOR]

The study presented the results of model experimental investigations on box structures made using additive manufacturing. The examined models had walls with reinforcements in the form of corrugations. An experiment was also conducted using a reference model without stiffeners. The aim of the study was to determine the influence of corrugation geometry on the shape and magnitude of structure deformations, as well as on the level of critical loads. The experiments were conducted using a dedicated research stand. Nonlinear numerical analyses of selected structure variations were also carried out using finite element method-based software. A comparison of the maximum displacement values obtained by experimental and numerical methods was made. [ABSTRACT FROM AUTHOR]

For scientific software, especially those used for large-scale simulations, achieving good performance and efficiently using the available hardware resources is essential. It is important to regularly perform benchmarks to ensure the efficient use of hardware and software when systems are changing and the software evolves. However, this can become quickly very tedious when many options for parameters, solvers, and hardware architectures are available. We present a continuous benchmarking strategy that automates benchmarking new code changes on high-performance computing clusters. This makes it possible to track how each code change affects the performance and how it evolves. [ABSTRACT FROM AUTHOR]

Hydrogels are polymeric materials with specific mechanical handling and encapsulation properties. Despite their widespread application, the modelling of the drying behaviour of hydrogels, particularly the evolution of texture stiffness with moisture loss, requires further development. This work aimed to develop numerical models to predict the moisture and deformation of cornstarch–alginate hydrogels under convective drying at 60 °C and 0.5 m/s. Cylindrical solids were used, and a transient three-dimensional FEM model predicted drying profiles via diffusion–convection mass transport. Texture analysis evaluating the hyperelastic coefficients of the hydrogels was performed for moisture contents ranging from 0.91 to 0.55 kg∙kg−1 w.b., yielding Young's modulus values from 24 to 147 kPa. A dimensionless relationship between the moisture ratio and elastic modulus produced a stiffness coefficient, used to adjust the moving boundary velocity and predict volumetric deformation. The model fitting returned an R2 higher than 0.95 and an RMSE lower than 0.04. The FEM model simulated hydrogel shrinkage by assessing the molar flux of water and mesh deformation at the boundaries, with mass diffusivity ranging from 2.38 to 5.46 × 10−10 m2∙s−1. Shrinkage reduced the surface area of solids during drying, revealing a pseudo-constant rate period in the drying profiles. The developed models effectively describe the drying of food materials with high shrinkage ratios. [ABSTRACT FROM AUTHOR]

Abstract The effect of lateral confinement in reinforced concrete slabs is widely recognized for its ability to increase the supported ultimate load. In this context, this study proposes a reliability analysis of slabs designed according to Brazilian standards, considering or not the phenomenon, with the goal of establishing a comparison between the cases. A numerical model developed in ANSYS software, calibrated from experimental results, was used to determine the slabs' failure loads. The Monte Carlo Simulation Method was employed to obtain the failure probabilities and reliability indexes. Additionally, a parametric study was conducted to understand the main factors influencing the reliability, whether considering lateral confinement or not. The results indicated a significant increase in the reliability of the slabs when lateral confinement was considered, raising the average reliability index from 3.29 to 4.44. The parametric study revealed that the factors influencing the reliability of confined slabs are similar to those obtained when not considering it, as also demonstrated by the strong correlation between the reliability indexes of confined and unconfined slabs.

Cellular beams are an attractive engineering solution due to their high strength to weight ratio, allowing for a design even lighter and more cost efficient in steel structures. These beams possess enhanced strength and stiffness compared to regular I-section beams of similar weight, due to their higher second moment of area. However, their variable cross-sections along the length introduce different modes of failure, making further research necessary, since there is a lack of standardized processes for their design. This paper investigates the design and verification procedures proposed by Ward (1990), Annex N (1998), Veríssimo et al. (2013), Fares et al. (2016), and Grilo et al. (2018) through a parametric study of cellular beams with varying geometries. To assess the buckling characteristics of cellular beams, shell finite element models are employed, which were previously validated, using experimental tests conducted by other researchers. The results obtained from a Python code implementing these design methods are then compared with Finite Element Method (FEM) analysis results for 80 beams. It can be concluded that the design methods provide conservative results for beams with intermediate or long spans. On the other hand, for beams with short spans, these methods may yield values that compromise safety. Finally, based on the FEM analysis results, a Hybrid Design Method (HDM) is proposed, which incorporates the verification procedures analyzed. This proposed method presents a better failure mode detection and limited load capacity when applied to cellular beams made from regular Brazilian I-section beams. [ABSTRACT FROM AUTHOR]

In this paper, we present a bolt preload monitoring system, including the system architecture and algorithms. We show how Finite Element Method (FEM) simulations aided the design and how we processed signals to achieve experimental validation. The preload is measured using a Piezoelectric Micromachined Ultrasonic Transducer (PMUT) in pulse-echo mode, by detecting the Change in Time-of-Flight (CTOF) of the acoustic wave generated by the PMUT, between no-load and load conditions. We performed FEM simulations to analyze the wave propagation inside the bolt and understand the effect of different configurations and parameters, such as transducer bandwidth, transducer position (head/tip), presence or absence of threads, as well as the frequency of the acoustic waves. In order to couple the PMUT to the bolt, a novel assembly process involving the deposition of an elastomeric acoustic impedance matching layer was developed. We achieved, for the first time with PMUTs, an experimental measure of bolt preload from the CTOF, with a good signal-to-noise ratio. Due to its low cost and small size, this system has great potential for use in the field for continuous monitoring throughout the operative life of the bolt. [ABSTRACT FROM AUTHOR]

In this paper, Computing the eigenvalues of the Conformable Sturm-Liouville Problem (CSLP) of order 2α, 1/2 < α; ≤ 1, and dirichlet boundary conditions is considered. For this aim, CSLP is discretized to obtain a matrix eigenvalue problem (MEP) using finite element method with fractional shape functions. Then by a method based on the asymptotic form of the eigenvalues, we correct the eigenvalues of MEP to obtain efficient approximations for the eigenvalues of CSLP. Finally, some numerical examples to show the efficiency of the proposed method are given. Numerical results show that for the nth eigenvalue, the correction technique reduces the error order from O(n4h²) to O(n²h²). [ABSTRACT FROM AUTHOR]

This paper offers a concise critical review of finite element studies of the jetting phenomenon in cold spray (CS). CS is a deposition technique wherein solid particles impact a substrate at high velocities, inducing severe plastic deformation and material deposition. These high-velocity particle impacts lead to the ejection of material in a jet-like shape at the periphery of the particle/substrate interface, a phenomenon known as "jetting". Jetting has been the subject of numerous studies over recent decades and remains a point of debate. Two main mechanisms, Adiabatic Shear Instability (ASI) and Hydrodynamic Pressure-Release (HPR), have been proposed to explain the jetting phenomenon. These mechanisms are mainly elucidated through finite element method (FEM) simulations, a numerical technique rooted in continuum mechanics. However, it is important to emphasize that FEM is limited by the equations established for analysis, and as such, its predictive capabilities are confined to those principles clearly defined within these equations. The choice of employed equations and approaches significantly influence the outcomes and predictions in FEM. While recognizing FEM's capabilities, this study reviews the ASI and HPR mechanisms within the context of CS. Additionally, this paper reviews FEM's algorithms and the core principles that govern FEM in calculating plastic deformation, which can lead to the formation of jetting. [ABSTRACT FROM AUTHOR]

The adaptation of traditional roads (tRoads) into electrified roads (eRoads) generally requires the inclusion of a charging unit (CU) in the pavement. In this study, the structural behaviour of a conductive eRoad is assessed using 2-D FEM simulations, and compared to the behaviour of a tRoad. Thermal and mechanical loadings representative of field configurations were applied and the relaxation response of the bituminous mixtures was calculated. Resulted strain and stress fields indicated a differential thermomechanical behaviour of the eRoad components. Strain and stress concentrations due to daily temperature fluctuations were pronounced near the interface with the CU. Traditional parameters obtained at the bottom of the bituminous layer were found similar for tRoad and eRoad. It is concluded that the development of new failure criteria is necessary to predict the service life of eRoads, in order to consider the thermally-induced strain and the impact of the volumetric rearrangement of the CU. [ABSTRACT FROM AUTHOR]

A finite element formulation based on sinusoidal shear deformation theory is established to investigate linear and nonlinear bending analysis of functionally graded porous (FGP) beams. Three different porosity distribution patterns are considered along the thickness of the beams. Nonlinear Von-Kármán strains are assumed to study the nonlinear behavior of FGP beams. The minimum total potential energy principle is applied to derive the governing equations and the equations are solved numerically by a finite element model. Parametric studies are performed for bending analysis of FGP beams, where the effects of porosity distribution pattern, porosity coefficient, length-to-height ratio and distributed load type are examined. [ABSTRACT FROM AUTHOR]

This paper investigates the failure mechanism of the rear drive shaft in a modified pickup truck which had operated for about 3000 km. The investigation included macroscopic and microscopic evaluation to document the morphologies of the fracture surface, measurement of the material composition, metallographic preparation and examination, mechanical testing, and finite element modelling and calculations. The results obtained suggest that rotation-bending fatigue was the primary cause of the drive shaft failure. The crack initiation is located in the root of the machined threads on the drive shaft surface and expanded along the side of the machining line surface. The main cause of fatigue cracks is attributable to a high stress concentration owing to a large unilateral bending impact under overload. Meanwhile, the bidirectional torsional force also produces a higher stress concentration and thus accelerates the fatigue crack to expand radially along the surface. Furthermore, the hardness of the central section of the drive shaft was marginally below standard. This deficiency results in harm to the bearings and other mechanical components, as well as expediting the enlargement of cracks. Finite element analysis revealed significant contact stress between the bearing and drive shaft, with stress levels exceeding the fatigue limit stress of the parent material. This highlights the need for reevaluation of the heat treatment process and vehicle loading quality to enhance the drive shaft's longevity. [ABSTRACT FROM AUTHOR]

Modern aircraft are being equipped with high-voltage and direct current (HVDC) architectures to address the increase in electrical power. Unfortunately, the rise of voltage in low pressure environments brings about a problem with unexpected ionisation phenomena such as arcing. Series arcs in HVDC cannot be detected with conventional means, and finding methods to avoid the potentially catastrophic hazards of these events becomes critical to assure further development of more electric and all electric aviation. Inductive sensors are one of the most promising detectors in terms of sensitivity, cost, weight and adaptability to the circuit wiring in aircraft electric systems. In particular, the solutions based on the detection of the high-frequency (HF) pulses created by the arc have been found to be good candidates in practical applications. This paper proposes a method for designing series arc fault inductive sensors able to capture the aforementioned HF pulses. The methodology relies on modelling the parameters of the sensor based on the physics that intervenes in the HF pulses interaction with the sensor itself. To this end, a comparative analysis with different topologies is carried out. For every approach, the key parameters influencing the HF pulses detection are studied theoretically, modelled with a finite elements method and tested in the laboratory in terms of frequency response. The final validation tests were conducted using the prototypes in real cases of detection of DC series arcs. [ABSTRACT FROM AUTHOR]

In this article, several designs of the active region of the THz radiation source are considered, taking into account grown super-multiperiod AlGaAs/GaAs superlattices. For the proposed designs, the principal device characteristics are computed: energy band diagram, gain spectrum, and transport characteristics. Based on the calculation results, the authors proposed an optimal design of the active region of a tunable THz radiation source. [ABSTRACT FROM AUTHOR]

Artificial intelligence (AI) shows good potential for detecting and discriminating faults in electrical machines, however, they require initial training with sufficient data, which is almost impossible to collect for working electrical machines in the field. This paper proposes an effective approach to solve this problem by getting the required training data from exact simulation results. To evaluate this idea, the finite elements method is used to simulate a three-phase induction motor (IM) in the healthy state as well as the stator inter-turn fault, broken rotor bar fault, and mixed eccentricity fault conditions. Then, for every fault condition, some fault indices are extracted from the stator line current and used to arrange and train a suitable support vector machine (SVM) model to detect and discriminate the fault condition. A similar IM is prepared in the laboratory, where, its stator line currents are sampled and recorded under the healthy and the fault conditions, and the same fault indices are extracted from the stator currents. Some penalties, which are determined by comparing experimental test results and corresponding simulation results in the healthy state, are applied to the experimentally attained values of the indices. The modified indices are then applied to the trained SVM models, where, the attained results confirm the trained SVM models are equally able to detect and discriminate the faults in the real IMs. [ABSTRACT FROM AUTHOR]

This paper concerns the evaluation of blank material influence on springback of irregularly shaped stamping after drawing operation to keep the dimensions and tolerances of stamping after the drawing process which are given in part drawing. Simulation of the drawing process and consequent stamping springback were carried out by PAM-STAMP 2G™ software which uses the finite elements method, with the use of blanks from strip steels DX54D, HC220P, HX220BD and HX220YD. Two mesh strategies for drawing tool parts in the software PAM-STAMP 2G™ were compared. Stamping springback was evaluated with the use of a reference points system. Critical areas of deformations and stamping springback were evaluated. Simulation results were compared with measurements on real stampings. The most suitable strip steel in terms of achieving the minimum size of springback after stamping drawing was evaluated. [ABSTRACT FROM AUTHOR]

This paper presents a novel approach to the simulation of the most common type of Cloud to Ground lightning strikes applied to a Photovoltaic farm with the view to validating its lightning protection system generally based on the electro geometric model as prescribed in the relevant international standards. It will be limited to the study of the electrostatic field distribution generated by a downward stepped leader progressing towards a large Photovoltaic Farm with a focus on its effect on the power electronics converters operating under lightning stress conditions. The Simulation was programmed using MATLAB’s Partial Differential Equations Toolbox based on the Finite Elements Analysis.

The paper outlines a finite elements refined mathematical model of the stress-strain state of single shaft gas turbine engine that can be used in ground or floating power plants. The mathematical model, built on the basis of special contact finite elements takes into consideration the contact thermoelasticity problem in the joint area of disk and blades. On the basis of the developed mathematical model the fields of turbine rotor dynamic stresses and displacement have been found too. To make the clear decision about the developed mathematical model adequacy mostly loaded impeller dynamic stresses field has been found and verified by comparison with the calculated results without contact and experimental data. The divergence between the calculated data and experimental results is less than 8%. The turbine rotor displacements and dynamic stresses have been found for different forced vibration modes for the wide range of harmonic indexes changing from 0 to 4. The obtained results along with the previous studies of this rotor fluid flow and thermal state could be used in further studies of the turbine rotor creep and fatigue strength and blades crack researches.

Deviation from the nominal dimension in the sense of component distortion is a quality‐reducing phenomenon in the foundry. This distortion problem as a result of impeded solidification and cooling shrinkage is of particular importance for permanent mold casting with its mechanically stiff and thermally well‐conducting molds. In studies, the temperature when the mold constraint is removed has already been identified as one of the dominant factors influencing the dimensional deviations of the casting. So far, however, no clear dependencies have been described. In the present work, the temperature up to the removal of the mold constraint is varied from near solidus to ambient temperature on a specially designed permanent mold casting made of AlSi7Mg0.3. This is compared with thermally and mechanically coupled finite elements method calculations of the investigated test geometry and the resulting component distortions. Finally, the applicability of the distortion prediction for the development of compensation strategies is evaluated. [ABSTRACT FROM AUTHOR]

How morphogenesis depends on cell properties is an active direction of research. Here, we focus on mechanical models of growing plant tissues, where microscopic (sub)cellular structure is taken into account. In order to establish links between microscopic and macroscopic tissue properties, we perform a multiscale analysis of a model of growing plant tissue with subcellular resolution. We use homogenization to rigorously derive the corresponding macroscopic tissue-scale model. Tissuescale mechanical properties are computed from microscopic structural and material properties, taking into account deformation by the growth field. We then consider case studies and numerically compare the detailed microscopic model and the tissue-scale model, both implemented using the finite element method. We find that the macroscopic model can be used to efficiently make predictions about several configurations of interest. Our work will help making links between microscopic measurements and macroscopic observations in growing tissues. [ABSTRACT FROM AUTHOR]

This paper investigates the failure mechanism of the rear drive shaft in a modified pickup truck which had operated for about 3000 km. The investigation included macroscopic and microscopic evaluation to document the morphologies of the fracture surface, measurement of the material composition, metallographic preparation and examination, mechanical testing, and finite element modelling and calculations. The results obtained suggest that rotation-bending fatigue was the primary cause of the drive shaft failure. The crack initiation is located in the root of the machined threads on the drive shaft surface and expanded along the side of the machining line surface. The main cause of fatigue cracks is attributable to a high stress concentration owing to a large unilateral bending impact under overload. Meanwhile, the bidirectional torsional force also produces a higher stress concentration and thus accelerates the fatigue crack to expand radially along the surface. Furthermore, the hardness of the central section of the drive shaft was marginally below standard. This deficiency results in harm to the bearings and other mechanical components, as well as expediting the enlargement of cracks. Finite element analysis revealed significant contact stress between the bearing and drive shaft, with stress levels exceeding the fatigue limit stress of the parent material. This highlights the need for reevaluation of the heat treatment process and vehicle loading quality to enhance the drive shaft’s longevity.

Cellular porous structures are used as an alternative to blocking structures in industrial fields where multi-functionality and mechanical efficiency are necessary. Many industries, such as automotive, aerospace and defense, utilize the benefits of these structures due to their high specific strength, outstanding noise and vibration damping abilities, thermal shielding, and superior specific energy absorption capacities. This study aims to reveal energy absorbing behavior and deformation mechanisms under compression load of Gyroid and Diamond cell based triply periodic minimal surface (TPMS) structures manufactured by powder bed fusion (PBF) technology. The TPMS lattice structures fabricated using AlSi10Mg material were designed in different relative densities according to cell wall thickness and cell number. Crushing behaviors of these structures were numerically investigated with a commercial Ls-Dyna finite elements (FE) software. The numerical results were obtained in a good agreement with the experimental data. The FE analysis facilitated understanding of the deformation damage mechanisms and stress distribution on the cell surfaces of the TPMS lattice structures designed with different relative densities. The findings of the study demonstrated that peak stress values computed during crushing of the TPMS lattice structures go up significantly with increasing relative density. Crush force efficiency (CFE) and energy absorption capacity of the TPMS lattice structures remarkably varied depending on deformation damage mechanisms occurred during crushing process. The highest CFE values for the Diamond and Gyroid cell-based lattice structures was obtained as 54% and 51%, respectively. Moreover, it was found that specific energy absorption capacity of the Diamond cell based TPMS lattice structures is 50% more than that of the Gyroid cell based TPMS lattice structures with close relative densities. [ABSTRACT FROM AUTHOR]

Calcium dynamics is not only responsible for maintaining the framework and functions of the cell but also plays a role in the dynamics of other biochemical systems in the cell. Phospholipase C- γ l ( PLC ) has a crucial role in the function of fibroblast cells. Experiments have shown that PLC and C a 2 + have interdependent dynamics in fibroblast cells. However, no reaction–diffusion model exists for the two-way feedback system dynamics of C a 2 + and PLC in fibroblasts till date. The computational model is designed to investigate the impact of variations in several processes, such as the SERCA pump, buffer process, source inflow, etc., on the system dynamics of C a 2 + and PLC in fibroblast cells. The computational findings are obtained using finite element techniques, and the consequences of dysregulation in various processes on the spatiotemporal calcium and PLC dynamics in fibroblasts are investigated. The results lead to the conclusion that the effects of buffer, source influx, diffusion, and SERCA pump can cause fluctuations in the dynamics of C a 2 + and PLC in fibroblasts. Disruptions in these constitutive processes can result in changes in the dynamics of calcium and PLC . Thus, the current model provides new/novel information regarding the precise dysregulatory constitutive systems that regulate calcium and PLC kinetics, such as source inflow, diffusion, SERCA , and buffer, can be responsible for excessive calcium and PLC concentrations leading to fibrotic illnesses such as cancer and fibrosis. [ABSTRACT FROM AUTHOR]

Induction surface hardening, which is used in various fields in the aerospace industry, is an important technology due to its accuracy, repeatability and energy efficiency. By modeling this heat treatment, the process parameters and efficiencies will be understood and its effective use in critical aircraft application areas will be expanded by contributing to the development of this technology. In this study, the induction surface hardening process of the cylindrical sample from AISI 4340 steel issimulatedusing couple field analysis. The coil geometry isoptimized using two approaches to achieve homogeneous temperature distribution on the heated sample surface. One is to change the diameter of the coil rings and the other is to change the interval of the coil rings. After the diameters of the coil rings optimization, uniformity isachieved at the sample surface temperature, with deviations up to ±4°C from the austenitizing temperature. After the intervalsof the coil rings optimization, homogenous temperature distribution isachieved at the sample surface temperature, and deviations from the austenitizing temperature areup to ±3°C. The current value required for heating the sample surface to the austenitizing temperature in 2s has beenreduced, and energy savinghave beenobtained.

In microrobotics field, self-reconfigurable modular robots (SRMRs) offer several advantages including adaptation to uneven environments, the capability of handling various sets of tasks, and continuous operation in the case of a malfunction of a single module. The current research direction in self-reconfigurable robotic systems is towards reaching million level number of modules working in coherence by means of locomotion, self-reconfiguration, and information flow. This research direction comes with new challenges such as miniaturizing the modules. One should consider looking for alternative ways of locomotion and self-reconfiguration when dealing with SRMRs having million level number of modules. Externally actuating the modules can be a good alternative to micro SRMRs. In this study, we developed a novel motion mechanism for a single module in a micro SRMR system by using external magnetic actuators. An assembly of elastic microtubes and permanent magnets is attached inside a cube-shaped module and periodic motion of the assembly is applied. The motion of a single microtube with permanent magnets inside is generated by using COMSOL Multiphysics software. The results of the simulations are compared with theoretical values to validate the motion mechanism that is introduced in the study.

Abstract This paper presents a methodology for the generation of a static reluctance network, with magnetomotive sources only in the rotor, applied in the analysis and design of surface mounted permanent magnet synchronous generators. In the analysis stage, this network can provide the magnetic flux in several points of the generator, enabling an estimate of the generator performance. In the design process, on the other hand, it provides the armature linkage flux and hence the induced EMF can be calculated. It is worth mentioning that the proposed methodology makes use of a good discretization level (high number of elements) on the teeth tips and in the air gap of the generator, in order to get better precision on the flux modeling of these regions. The main contribution of this paper is to present the development process of a static reluctance network applied to surface mounted permanent magnets synchronous generators with different dimensions. The proposed model has proved to be robust and flexible as it can be seen in the results. The reluctance network (RN) developed with the proposed methodology presented in this paper shows low variations of the magnetic flux values, when compared with finite element simulations.

Traditional machining in micro-scale still presents many challenges associated with bad chip formation, presence of high burrs, elevated tool wear and low surface quality. Most problems in micro-machining are a consequence of the size effect, which is the similarity in the scale sizes of the cutting-edge radius of the tool and the minimum uncut chip thickness (MUCT). Micro-machining tends to be even more challenging for low-machinability alloys, such as Inconel 718. Through the finite element method (FEM), it is possible to estimate the minimum uncut chip thickness of a material providing that the constitutive model that describes its elastoplastic behavior is known. Therefore, the objective of this contribution is to analyze the chip formation in orthogonal micro-cutting of Inconel 718 using numerical FEM simulations and the Johnson–Cook plasticity model in an explicit scheme. Two cutting tools were modelled with different edge radius in order to represent a sharp tool and a tool that suffered rounding of the tip because of wear. Simulations were carried out with different values of feed per tooth in order to determine which value is closest to MUCT. The Mises stress and accumulated plastic strain were monitored, as well as the cutting forces. The results show that the rounded tool, with an edge radius of 5 µm, leads to higher forces, worse chip formation and worse surface quality when compared to the sharp tool, with an edge radius of 1 µm. [ABSTRACT FROM AUTHOR]

The paper presents the results of experimental studies and numerical analyses using the Finite Elements Method for a planar structure subjected to pure shear. The test specimen was made using an Fused Filament Fabrication incremental technique. In order to correctly represent the mechanical properties of the structure, a series of tests were performed to determine the physical constants of the model material used. Due to the perfect physical nature of the numerical model, in contrast to experimental phenomena, a suitable method was employed to induce the post-critical deformations in the analysed structure. [ABSTRACT FROM AUTHOR]

A problem of determining the characteristics of a semiconductor can be reduced to the study of the quasi-variational inequality, (J. Abouchabaka, R. Aboulaïch, A. Nachaoui and A. Souissi, COMPEL18 (1999) 143–164.) where the obstacle M(u) is the solution of an elliptic problem depending on u. We present here an hybrid finite element method for the computation of obstacle M(u) and we discuss some numerical aspects appearing in its approximation. [ABSTRACT FROM AUTHOR]

Various process nonhomogeneities in the cold rolling lead to an uneven distribution of deformation across the strip cross-section, resulting in the induction of residual stresses. This study investigates the longitudinal residual stresses in cold-rolled EN AW-5083 aluminum alloy strips using the finite element method (FEM) to achieve reliable predictions. The impacts of process parameters, including the reduction ratio, coefficient of contact friction, and front and back tensions, were analyzed. Changes in residual stresses, depending on the process parameters, were determined by the distribution of linear and shear strains, as well as the strain hardening conditions at the exit part of the deformation zone. An increase in the reduction ratio from 20 to 50%, as well as an increase in the friction coefficient from 0.1 to 0.2, resulted in decreased stress values. The residual stresses on the strip surface, determined by the experimental deflection method, were consistent with the results obtained by FEM simulation. Under the impact of back and/or front tensions, there is a reduction in longitudinal residual stresses, with the front tension exerting the greatest influence. The research results show that the FEM is a reliable tool for predicting residual stresses in cold-rolled strips.