Developed Finite Element Method Model Research Articles

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

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

Investigation of the tensile deformation behaviour in Ni-based superalloy inconel alloy 617 using EBSD-based finite element simulations and optical flow method

To improve component design, the fundamental understanding of the fatigue behaviour of gas turbine materials is essential. Since Ni-alloys exhibit pronounced elastic anisotropy, the local grain orientation strongly affects the stress and strain distribution in the material under mechanical loadings. This work addresses the characterisation of anisotropic elastic–plastic deformation and its consequences for crack initiation of nickel-base superalloy IN617 under tensile loading. Samples were loaded in situ in a scanning electron microscope (SEM) to correlate the deformation behaviour with the grain structure and the grain orientation determined by electron backscatter diffraction (EBSD) measurements. To calculate the resulting stresses and strains, the EBSD data were used to develop a model by finite element method (FEM) considering the grain structure and orientation. The results of the elastic–plastic finite element (FE) simulation were compared with the theories of the E⋅m model based on the Schmidt factor (m) and anisotropic Young’s modulus (E). A mathematical image registration method called “optical flow method” (OFM), which is capable to calculate the transformation of EBSD measuring points during deformation, was applied to the EBSD data. The strains calculated by the optical flow method and by FE simulation were compared for two samples. The findings revealed large strains in the later crack initiation area found in both the OFM and FEM. The developed FEM model was verified by the successful correlation of hypotheses of the E·m model with the simulated mechanical behaviour. Furthermore, the impact of the microstructural neighbourhood on the mechanical behaviour was emphasised.Graphical

Concept Design of a High-Voltage Electrostatic Sanitizer to Prevent Spread of COVID-19 Coronavirus

In addition to public health measures, including social distancing, masking, cleaning, surface disinfection, etc., ventilation and air filtration can be a key component of a multi-pronged risk mitigation strategy against COVID-19 transmission indoors. Electrostatic precipitators (ESP) have already proved their high performance in fluid filtration, particularly in industrial applications, to control exhaust gas emissions and remove fine and superfine particles from the flowing gas, using high-voltage electrostatic fields and forces. In this contribution, a high-voltage electrostatic sanitizer (ESS), based on the electrostatic precipitation concept, is proposed as a supportive measure to reduce indoor air infection and prevent the spread of COVID-19 coronavirus. The finite element method (FEM) is used to model and simulate the proposed ESS, taking into account three main mechanisms involving in electrostatic sanitization, namely electrostatic field, airflow, and aerosol charging and tracing, which are mutually coupled to each other and occur simultaneously during the sanitization process. To consider the capability of the designed ESS in capturing superfine particles, functional parameters of the developed ESS, such as air velocity, electric potential, and space charge density, inside the ESS are investigated using the developed FEM model. Simulation results demonstrate the ability of the designed ESS in capturing aerosols containing coronavirus, precipitating suspended viral particles, and trapping them in oppositely charged electrode plates.

Simulation and Experimental Investigation of a Two-Stage Magnetic Precession Gear

Gears are common and important components of many types of propulsion systems applied in mechanical engineering. The aim of this paper is to present the mechanical design and performance analysis of a novel two-stage magnetic precession gear (MPG). The main advantage of the proposed design is the ability to obtain higher transmission ratios than other currently known magnetic gear types. A detailed analysis of the performance of the MPG was carried out employing a developed numerical model of the magnetic field in the proposed gear. The MPG model is based on the finite element method (FEM) and allows determining the relations between the torque acting on the main components of the gear, load angles, and air-gap lengths. To validate the developed FEM model, the prototype of an MPG with a 1/144 gear ratio was built and tested. The experiments were also focused on determining the mechanical efficiency as well as the influence of rotational speed and lengths of air gaps on the maximum load torque. The tests indicated that the maximum efficiency of the studied MPG is about 30%, which is comparable to the efficiency of mechanical two-stage precession gears with face meshing.

Analysis of DC reversal error of the calorimetric thermal voltage converter

One of the most precise standards of AC voltage in the frequency range from 1 MHz to 100 MHz is the Calorimetric Thermal Voltage Converter (CTVC) designed at National Research Council (NRC) in Ottawa, Canada. Unfortunately, this converter has a few times higher value of DC reversal error than other known thermal voltage converters (TVC). This article presents analysis of possible reasons of such a high DC reversal error and discusses possible ways of its reduction. The analysis is performed using finite element method (FEM) simulations. The correctness of the developed FEM model was validated with published results of investigation of the physical model of the CTVC designed and constructed in NRC. This article presents also improved construction of a CTVC and laboratory measurements of its DC reversal error which is about 89% lower than in the case of NRC CTVC.

Simulation of hot air infrared‐assisted green peas drying using finite element method

AbstractThe objective of this study was to simulate the drying kinetics of green peas in a hot‐air infrared‐assisted dryer using an appropriate finite element method (FEM). To achieve the aim of the study, the axisymmetric FEM with the Galerkin approach was employed to model and predict the drying behavior. One of the key physical properties required for the modeling was to determine the effective moisture diffusivity obtained from previous study on green peas drying in a lab‐scale hot‐air infrared‐assisted dryer. To compare the simulated moisture transfer results with those of experiments several experiments consisting of combination of main factors namely drying air temperatures (30°C, 40°C, and 50°C), infrared power intensity (0 as a control, 0.2, 0.4, and 0.6 W cm−2), and drying air flow velocity (0.5, 1, and 1.5 ms−1) were conducted in three replications. The predicted average moisture contents by the proposed mathematical model showed reasonably a good agreement with the experimental data (maximum error value: RMSE = 2.18 and MARE = 5.08%). The simulation was also compared by two‐dimensional FEM. The results demonstrated that the accuracy of the axisymmetric FEM was higher than two‐dimensional FEM. Based on the results, the developed FEM model has reasonable accuracy and can be applied to provide more information on the dynamics of moisture movement without running any experiments. Furthermore, the useful information about optimum design of industrial dryers and drying behavior can be achieved by simulation of the drying process.Practical ApplicationsFood security is an important issue for every developing country. Fruits are a major source of nutrients that widely used as fresh or processed. Drying process is widely used to improve the security, quality, shelf time, and also the packaging and transportation of the foodstuff. Design of dryer requires a high degree of attention. The useful information about optimum design of dryer and drying behavior can be achieved by simulation of the drying process. In this study, the finite element method is used to model and simulate the drying process of green peas (Pisum sativum L.). Green peas are one of the ancient cultivated and nutritious popular vegetables with a most useful amount of fiber that enjoy the antioxidant and anti‐inflammatory benefits.

Numerical investigation on the forming behaviour of stainless/carbon steel bimetal composite

Bimetal composites have wide applications due to their excellent overall performance and relatively low comprehensive cost. The aim of this study is to investigate the forming behaviour of stainless/carbon steel bimetal composite during stamping by finite element method (FEM). In this work, the bonding interface of bimetal composite sheet was assumed to be perfect without delamination during the plastic forming process for simplicity. Uniaxial tensile tests on base metal (carbon steel) and compositing metal (stainless steel) were first carried out, respectively, in order to obtain the tensile properties of each of the component materials required in the forming simulation. Processing variables, including the layer stacking sequence, relative thickness ratios of two layers and friction were considered, and their effects on the distributions of circumferential stress and thickness strain were analysed. The bimetal composite sheet was set as the eight-node solid elements in the developed FEM model, which is effective for evaluating the distributions of circumferential stress and thickness strain, and predicting the high-risk region of necking during the stamping of bimetal composites. The simulation results can be used as an evaluation indicator of the capability of forming machine to ensure the bimetal composite can be safely formed.

Tool Temperature and Process Modeling of Friction Stir Welding

Friction stir welding (FSW) has many advantages rather than fusion welding, but details of internal phenomena during its processes have not yet been clarified. In this study, a thermo-mechanically coupled process model was developed to investigate FSW phenomena inside a tool and workpiece. As a workpiece, 6061-T6 aluminum alloy was employed. The system of FSW process model includes several thermal boundaries. Among heat flows through these boundaries, heat transfers into the exterior of the system become more sensitive to tool and workpiece temperatures than heat transfers within the system. This paper especially focused on a heat transfer coefficient at a workpiece bottom, and optimized it through experiments and finite element method (FEM) analyses. The tool temperatures during FSW were measured with a special tooling system with imbedded thermocouples within a tool. As a result, an analysis model that is able to investigate details at a wide range of traverse speeds was developed for practical high speed welding. Then, the accuracy of developed FEM model was validated with them. Finally, the temperatures and stress distribution around workpiece/tool interfaces were investigated with the developed model.

High-temperature static strain langasite SAWR sensor: Temperature compensation and numerical calibration for direct strain reading

Strain sensing for extreme environments such as aerospace, power generation, and industrial applications require robust sensors capable of sustaining the targeted high-temperatures, while maintaining a stable sensor response. Current technologies face challenges regarding device or system size, complexity, operational temperature, or dynamic range. Surface acoustic wave resonator (SAWR) sensors fabricated on langasite (LGS) using Pt-alloy based electrodes are capable of withstanding temperatures up to 1000°C, have a small footprint, are battery-free, and can be wirelessly interrogated, thus presenting themselves as a promising technology for harsh-environment strain sensing. This paper presents direct SAWR strain sensor readings up to 114με on a constant stress beam between 24°C and 400°C. In order to obtain the direct strain reading at high-temperature, a finite element method (FEM) numerical model was developed. The FEM model was compared to measurements performed using a room temperature commercial sensor, and revealed correlation between the measured and modeled strain data close to unity. At elevated temperatures, the SAWR frequency measurements were calibrated using the developed FEM model adapted for operation at high-temperatures, due to the absence of a reliable high-temperature static strain sensor. A temperature compensation scheme was employed to mitigate temperature-strain cross-sensitivity, and Savitzky-Golay signal processing filtering employed to improve signal detection. Ceramic Al2O3-based epoxy was used to attach the sensor to the targeted constant stress beam fixture, and −41Hz/με sensitivity was obtained at 400°C. The sensor fabrication, calibration and measurements reported in this work illustrates the capability of LGS based SAW resonators to perform as high-temperature harsh-environment static strain sensors.

Cutting forces prediction and thermal distribution considering various cutting parameters and wear progression in drilling

Purpose The purpose of this paper is to develop a finite element method (FEM) supported simulation of drilling process applied to superficially hardened steels and assess the heat treatments effect on the optimum drilling conditions (feed rate, speed, etc.). Design/methodology/approach A three-dimensional model was developed simulating the drilling procedure while experimental data, concerning the chip geometry and force components, were used to validate the model. The developed simulation will allow systematically insight on the tools wear progression induced by the developed temperature and stress fields. Two different cases of simulation were examined. A typical simulation was investigated, which erected with all the standard features found in the FEM simulation software. In the second case, all the experimental data were introduced. Findings The simulation results revealed that the advanced developed FEM model describes sufficiently the real chip geometry. Moreover, the FEM calculations provide an effective tool for predicting occurring temperatures, strain and stresses and thus for approaching the real loads of the cutting tool during drilling. Originality/value This paper fulfills an identified need to study the drilling simulation.

A Computational Model for Surface Welding in Covalent Adaptable Networks Using Finite-Element Analysis

Covalent adaptable network (CAN) polymers can rearrange their macromolecular network by bond exchange reactions (BERs), where an active unit attaches to and then replaces a unit in an existing bond and forms a new bond. When such macromolecular events occur on the interface, they can contribute to surface welding, self-healing, and recycling of thermosetting polymers. In this paper, we study the interfacial welding and failure of CANs involving both interfacial normal and shear stresses. To do this, we incorporate our recently developed multiscale model for surface welding of CANs with a cohesive zone modeling approach in finite-element method (FEM) simulation. The developed FEM paradigm involves a multiscale model predicting the interfacial chain density and fracture energy, which are transferred to a cohesive zone model to establish the surface traction-separation law. The simulations show good agreement with experimental results on the modulus and strength of welded samples. They also provide understanding of the interactions between surface welding and material malleability in determining the final mechanical properties of polymer structures. The developed FEM model can be applied to study other complex welding problems, such as polymer reprocessing with nonregular particle size and shape.

Prediction of the effect of porous sound-absorbing material inside a coupled plate cavity system

This paper predicts the acoustic properties of the porous sound-absorbing material in a box cavity by conducting a finite element method (FEM) analysis, and it verifies the estimated acoustic properties using an appropriate experimental method. The cavity is a rectangular box with five rigid walls and one flexible wall which is an aluminium plate. The porous sound-absorbing material is attached to the inner surface of the plate, in order to modify the coupling between the plate inner surface and the air inside the box. The plate is mechanically excited by using an electromagnetic shaker, which is imitating structure-borne noise. The generated noise is recorded by using pressure microphones at the different locations inside the box. The results show that there is good agreement between the FEM prediction and the measurement for the acoustic response at different locations inside the rectangular box. Sound pressure peaks due to cavity modes are effectively reduced by adding porous sound-absorbing material. Furthermore, sound level in the cavity is reduced by a similar amount in both the numerical simulation and the measurement, when a porous sound-absorbing material is added. The developed FEM model is used to characterise the effects of porous sound-absorbing material in reducing the structure-borne radiated noise.

A dynamic FEM simulation of the nano-impact test on mono- or multi-layered PVD coatings considering their graded strength properties determined by experimental–analytical procedures

Nano-impact test is a reliable method for assessing the brittleness of PVD coatings with mono- or multi-layer structures. For the analytical description of this test, an axis-symmetrical Finite Element Method (FEM) model was developed using the LS-DYNA software. This software was adequate to simulate the progressive superficial coating fracture induced by the repetitive nano-impacts during the nano-impact test. The coating possesses one or more individual layers with own mechanical properties, since every layer after its deposition at the PVD process temperature is exposed to an annealing affecting its strength data. The annealing duration of each layer is associated with the rest time, up to the deposition of the overall coating thickness. For simulating this procedure and estimating the related mechanical properties of the coating layers, cemented carbide specimens with the same TiAlN PVD (Physical Vapor Deposition) coating of various thicknesses and structures were annealed in vacuum. The annealing duration was equal to the deposition time required for coating a specimen with a further layer up to a constant overall thickness. The superficial strength properties of these coatings were determined via nano-indentations, coupled with FEM calculations to estimate the corresponding stress–strain curves. Results obtained by the developed FEM model simulating the nano-impact test were compared with experimental ones. Taking into account the sufficient convergence between them, the introduced numerical procedure can be effectively employed to evaluate the effect of various coating structures on their brittleness.