FEM Method Research Articles

Analytical and FEM Methods for Line Start Permanent Magnet Synchronous Motor of 2.2kW

This paper has developed electromagnetic equations based an analytical model to design a three-phase line start permanent magnet synchronous motor (LSPMSM) of 2.2 kW. In order to enhance the torque and efficiency of this machine, an optimized slot shape of rotor permanent magnet is proposed. The analytical model is first presented to evaluate the magnetic characteristics, and then analytical expressions are derived under the open circuit condition. The influence of the magnet size variables on the analytical model is considered to investigate the magnetic leakage flux and flux density distribution in air gaps. Moreover, the variation of design has a significant impact on the steady-state performance characteristics of this motor. In addition, in order to check the output results from the analytical model, a finite element method is developed to evaluate these solutions. Finally, experimental and simulation results have been compared and analyzed to validate the development of method.

ROLE OF HUMAN CAPITAL AND SOCIAL CULTURE IN POVERTY REDUCTION IN ACEH PROVINCE, INDONESIA

This study aims to examine the human capital factor in overcoming poverty in the people of Aceh Province and the role of socio-culture in overcoming poverty in Aceh Province. The poverty rate in Aceh province continues to increase while special autonomy and village funds are increasingly available; this is in contrast to the SDGs program. Quantitative research using panel data analysis with the FEM method as the best analysis tool. The Central Statistics Agency released the data used in the Aceh Province Village Potential in 2011, 2014, and 2018 with the number of observations in this study as many as 19,355 of 6505 villages in Aceh Province. Village-level poverty in Aceh Province can be assessed through human capital and socio-culture dimensions. The findings of the dimensions of human capital show that three variables have a significant effect: the number of private primary schools, private senior high schools, and distance to vocational schools. In comparison, the socio-cultural dimensions of variables that significantly affect cooperation are the availability of cinemas/pay-TV, karaoke/entertainment venues, and public spaces or fields. The quality of community welfare development must receive support from the government in providing facilities that support human capital activities and support from the surrounding community in creating a life based on solidarity or cooperation. Socio-cultural factors are an alternative strategy to poverty alleviation in the regions through a village-level approach.

Aerodynamic characteristics and structural behavior of sound barrier under vehicle-induced flow for five typical vehicles

Running vehicles cause disturbances in the surrounding air, which lead to a vehicle-induced aerodynamic load (VIAL) on roadside thin-wall structures. In this study, to reveal the aerodynamic load mechanism on roadside sound barriers subjected to the action of a vehicle-induced airflow, the Computational Fluid Dynamics(CFD) method is used to simulate the airflow around a running vehicle and adjacent to the sound barrier. First, the reliability of the numerical simulation is verified by comparing it with field tests. Second, using the CFD method, flow fields around the running vehicle with and without a sound barrier are obtained, the wind-pressure distribution is extracted, and the micro-mechanism of the sound barrier’s influence on the airflow around the running vehicle is revealed by comparing and analyzing the flow-field distribution characteristics. Thirdly, through parametric studies, the changing rules of the wind-pressure distribution and the VIAL effect of internal force on the sound barrier screen are presented under different conditions, i.e., sound barrier height, vehicle shape, vehicle–barrier separation distance, and sound barrier shape. Then, using the FEM method, the load effect of vehicle-induced airflow on the sound barrier column is revealed. The conclusions improve the understanding of the action mechanisms of the vehicle-induced airflow on roadside sound barriers.

Numerical & experimental assessment of mixed-modes (I/II) fracture of PMMA/hydroxyapatite nanocomposite

Nowadays, polymer-based nanocomposites widely used in biocompatible restorative materials and medical equipment and polymer-based nanocomposites are the most important of them. One of the most useful biocompatible polymers in this field is polymethyl methacrylate (PMMA). In this research, the experimental and numerical analysis of the fracture behaviors of PMMA nanocomposites that are reinforced with hydroxyapatite (HA) nanoparticles are investigated under pure mode I, pure mode II and mixed-mode (I/II) loading. For this purpose, notched semi-circular bend (SCB) specimens containing various Wt. % of HA nanoparticles and different notch angles were fabricated. Then, the mechanical properties of the specimens and the fracture toughness of the notched specimens were investigated. To evaluate the accuracy of nanomaterial distribution, scanning electron microscopy (SEM) images are analyzed and it was observed that at Wt. % of more than 1.5%, specimens with more cumulative masses of hydroxyapatite nanoparticles have more strength reduction. Also, to investigate the fracture behaviors of the produced specimens, the failure criteria of maximum tangential stress (MTS) and generalized maximum tangential stress (GMTS) were evaluated and it was observed that the GMTS criterion is more in line with the experimental results. In addition, the results showed that by increasing the Wt. % of HA nanoparticles from zero to 1% mass, the KIC value increased compared to the pure PMMA, whereas, by increasing this value to 1.5% mass, the fracture toughness decreased. Finally, the fracture initiation and propagation are evaluated using FEM and XFEM numerical methods and the values of stress intensity factors and crack growth path are predicted and compared with experimental values. The obtained numerical results are in good agreement with the experimental results.

Analisis kekuatan struktur ramp door haluan pada kapal Ferry Ro-Ro 1500 GT dengan variasi beban menggunakan Finite Element Method

Ramp Door is a door to put a vehicle into a Ro-Ro ship or any other type of ship that transports vehicles. The use of Ramp Door is needed to facilitate the process of unloading and loading vehicles from the crossing dock to the ship and vice versa. This study aims to analyze the strength of Ramp Door structure with load variations from various types of vehicles in order to compress the maximum stress results and safety factors. The method used is the FEM method with the help of an element-based application up to. The results of the study obtained the maximum stress value of Ramp Door Bow with MPV vehicle type at an even load is 43.26 MPa. In this type of SUV vehicle, the maximum stress with an even load is 50.37 MPa. In sedan vehicle type the maximum stress with an even load is 37.61 MPa. in commerial vehicle type the maximum stress with an even load is 45.70 MPa. In this type of small truck vehicle, the maximum stress with an even load is 81.53 MPa. In large truck vehicles the maximum stress with an even load is 302.48 MPa. In this type of vehicle, the maximum stress bus with an even load is 178.08 MPa. For the largest safety factor value is a type of Commercial vehicle with a value of 8.91. While the smallest safety factor value is the type of Big Truck vehicle with a safety factor value of 1.01.

LTB analysis of pre-stressed mono-symmetric thin-walled beams with deviators under non-uniform bending moments using a simplified FEM

A FE formulation has been newly presented for the lateral-torsional buckling (LTB) analysis of an externally pre-stressed (PS) steel beam, possessing deviators under non-uniform bending moments. Firstly, the total potential energies of the PS mono-symmetric thin-walled beams in possession of un-bonded/bonded deviators are derived depending on the number of deviators. Afterwards, the in-plane solutions of the PS mono-symmetric simple/cantilever beams under the lateral load can be analytically derived through the use of discontinuous functions. A simplified FE procedure is then developed based on the total potential energy, taking into consideration the effects of double tendons. Finally, the critical buckling loads of simple and cantilever PS mono-symmetric beams which were subjected to the non-uniform moments with the increasing of deviators are evaluated using the FEM and Rayleigh-Ritz method. As a result, the FE solutions were found to be very well matched to solutions by Ritz method and Abaqus. Additionally, the effects of double tendons, eccentricity, and the initial tension on LTB of the PS beam system were investigated with the increase of un-bonded/bonded deviators.

Study Analysis of Car Rim Design and Mechanical Properties Using Catia

This study discusses the design of a car rim and analyzed its mechanical properties using three different basic materials: aluminum, steel, titanium. The purpose of this study is to reduce production time and to minimize the risk of design failure. In this study using the Catia software to design a rim, then simulate the effect of applying force on a component, applying a certain working pressure, then able to perform calculations and display the results for analysis. The analytical method used is the FEM method of static analysis. The mesh type uses a linear tetrahedron mesh. Provision of clamps or fixed constraints is carried out on the surface of the bolt hole, where this surface is in contact with the wheel holder of car drive system. Then given a circumferential loading of 200 kN/m2. It was found that aluminum material is the best for the manufacture of car rims, which has a low density so it is lighter than steel and titanium. However, alloys such as lead and magnesium are needed to increase their hardness, and chromium alloys are needed to protect the rims from corrosion due to use in a polluted environment and contain impurities that can trigger corrosion.

Dynamic Analysis of Block-Type Machine Foundation Using Barkan’s Model for Various Soil Parameters

Machine foundation involves both the static loads and the dynamic loads caused by working of the machine. The machine weighs several tons and is required to restrict amplitudes to only a few microns. Inadequately constructed foundations may result in failures exceeding many times the cost of the capital investment required for properly designed foundations. This necessitated a deeper scientific investigation of dynamic loading and analysis. Method proposed by Barkan (recommended by IS: 2974-1982) for design of machine foundations under harmonic load, still remains the most popular method for vibration analysis of block foundations in Indian industry. Finite Element (FE) is very commonly accepted analysis tool for solution of engineering problems. Effective Pre and Post-processing capabilities make modeling and result interpretation simple. The current paper aims to do the parametric study of dynamic analysis of block foundation using Barkan’s method. For the same, three different machines of 150 rpm, 250 rpm and 450 rpm are taken into account and six different soil types: (a) Medium, Stiff and Hard Clay and (b) Loose, Medium and Dense Sand are considered. Foundation sizes are optimized according to soil cases and each case is analysed using conventional method and FEM model using STAAD Pro. for 0.8, 1 and 1.2 times the soil parameters to cover the confidence range. This study is further extended for the comparison of concrete quantity consumed. The results grossly show that as the clay varies from medium to hard, and sand from loose to dense, the foundation size required, decreases. It was seen that, with the increase in stiffness of soil, natural frequency of machine foundation soil system increases and amplitude of foundation reduces. Also, FEM method of analysis indicates safer amplitude of foundation compared to classical method of analysis, inferring to conventional method being conservative.

Verification, validation, and parameter study of a computational model for corrosion pit growth adopting the level-set method. Part I: Corrosion

Corrosion is a phenomenon observed in structural components in corrosive environments such as pipelines, bridges, aircrafts, turbines, etc. The computational model of corrosion should enjoy two features: a) accurately considering the electrochemistry of corrosion and b) properly dealing with the moving interface between solid and electrolyte. There are several approaches to model corrosion such as using FEM with mesh refinement algorithms, combining FEM and level-set method, employing finite volume methods, adopting peridynamic formulation, and utilizing phase field models. Because of its accuracy, lower computational cost, and robust dealing with multiple pit merging, the model which combines FEM with level-set method is selected to be more extensively assessed in this paper. Part I focuses on demonstrating the model’s capabilities of simulating pitting corrosion through a set of numerical examples which include numerical solution verification, experimental validation, and uncertainty quantification of model parameters and properties.

Design of PCF-SPR for Early Detection of Skin Cancer Infected Cells

In this work, we carried out a numerical investigation of the PCF-SPR biosensor for the early detection of infected skin cancer cells and healthy cells. The study was conducted using the COMSOL Multiphysics-based FEM method. The dielectric material used in this PCF design is fused silica, while the plasmonic material is gold. The study was conducted to test the effect of the thickness of the plasmonic layer and the size of the air hole diameter on the PCF-SPR. It was found that the larger the diameter of the air hole in the proposed sensor gives a smaller confinement loss value, while the thicker the plasmonic material used also gives a small confinement loss value. The proposed PCF-SPR has a wavelength sensitivity in detecting skin cancer-infected cells of 7000 nm/RIU. These results indicate that the proposed sensor has a good performance in detecting cells infected with skin cancer.

Multi-scale dimensionless prediction model of PEMFC sealing interface leakage rate based on fractal geometry

The performance of the sealing is closely related to the working efficiency and safety of PEMFCs and the interfacial leaking behavior is heavily influenced by the heterogeneous rough surfaces. And the BPPs and Gaskets of the fuel cell sealing structure are ultra-thin, which makes obtaining leakage rate by experiments difficult. In this paper, a highly efficient method to calculate the PEMFC sealing interface leakage rate is proposed based on the fractal geometry and numerical simulations. FEM and LBM methods are used to analyze the nonlinear contact and microscopic gas flow behaviors in the numerical simulation processes. Furthermore, a multi-scale dimensionless model of PEMFC interface leaking is established by numerical simulated results. The multi-scale dimensionless model can significantly reduce the negative influence of the single observation scale on interface leakage rate prediction accuracy and solve the problem of the inability to analyze interface leakage rates at different scales simultaneously. By comparison with the Roth's theory, the traditional model that only considers the small elastic deformation has a large deviation in the evaluation of the leakage rate of the rubber seal interface, while the multi-scale model can accurately predict the interface leakage rate under different PEMFC Gasket compression rates.

Experimental assessment of the temperature state of tractor diesel pistons

INTRODUCTION: The paper presents the operating conditions of tractor diesel engines that cause the appearance of thermal fatigue cracks on the edges of the piston combustion chamber. The presence of sharp edges of the combustion chamber in the pistons, which are stress concentrators, leads to an increase in the probability of their destruction and thereby limits the engine life of the diesel engine. The main reasons for the formation of cracks in the zone of the edge of the combustion chamber are indicated.
 AIMS: The aim of this study is the assessment of the temperature state of pistons of the D-240 and the D-245 tractor diesel engines, produced by Minsk Motor Plant (MMP).
 METHODS: Temperature gauging was carried out according to the method in order to identify the nature of changing of piston heads temperatures under stationary and nonstationary operation modes of diesel engines. Transfering of thermal electromotive force from thermocouples to measuring devices was carried out by means of an intermittent current collector. Imitaion of nonstationary operation modes was carried out by means of changing the cyclic feed of a high pressure fuel pump, using a reversible electric motor.
 RESULTS: The data of the temperature state of pistons under various stationary and nonstationary operation modes of engines is provided. It is noted that the temperature state of the D-245 diesel pistons has a higher level of heat stress compared to the D-240 diesel pistons. The maximum amplitude of low-frequency temperature fluctuations at the edge of the combustion chamber and their radial differences along the piston bottom are determined, depending on the parameters of thermal loading cycles. It is noted that the most dangerous modes of diesel operation, in terms of the destruction of the edge of the combustion chamber, are sharply changing modes (eg.: theloading unloading mode).
 CONCLUSIONS: It is proposed to increase the fuel injection advance angle in the thermal loading cycle in order to conduct accelerated comparative tests of piston variants for thermal resistance. The developed thermal loading cycle, in which the total duration of the load increase is 180 s and the total duration of the load decrease is 90 s, can be recommended for accelerated motor tests of pistons for thermal cycling resistance. The obtained temperature measurement data is recommended to clarify boundary conditions of the first kind when calculating the piston using the FEM method.

Impact of financial inclusion on banking stability in ASEAN countries –threshold financial inclusion

ABSTRACT This paper aims to investigate the effect of financial inclusion on bank stability in ASEAN countries. FEM, threshold estimation, and GMM method, respectively. The findings show that financial inclusion decreases the stability of banks, but the influence varies between banks and market structures. Furthermore, we examine the impact of the financial inclusion threshold on bank stability. The results show countries with financial inclusion above the threshold will increase stability, whereas countries with financial inclusion below the threshold will decrease the bank’s strength. Research on the non-linear impact of financial inclusion on bank stability through threshold model.

Dynamic response of wind turbine blade surface material under water droplet high velocity impact

When a wind turbine blade exposure to some degree of rainfall, water droplets in the atmosphere impact the blade at high velocity will causes erosion damages of the leading edge. The damages have significant influence to the aerodynamic performance of the blade, and also the cost of power generation. In this paper, a high velocity impact dynamics model of water droplet impact on wind turbine blade is develops based on SPH-FEM coupling method, where SPH model is used to model the large deformation region of the fluid domain, and FEM method is used to model the small deformation region of the structure domain. Together with properties of gelcoat material on the blade surface, effects of varying impact velocities and angles on the impact response of the gelcoat material are analysed through numerical simulation. The results show that during a high velocity impact event of water droplet, the contact force history appears two peaks. Also contact forces and strains on the blade material decreases with decreasing droplet impact velocity and impact angle, the total contact duration of the droplet during the impact decreases with increasing droplet impact velocity and angle. The present study is expected to provide theoretical guidance for enhancing the erosive capacity of wind turbine blade gelcoat material.

Analysis and Calculation of the Three-Dimensional Air-Gap Magnetic Field and Electromagnetic Torque of a Multishaft Ring-Plate Magnet Gear

A kind of multishaft ring-plate magnet gear (MRMG) structure is proposed. Because an MRMG has the characteristics of an eccentric permanent magnet gear with a small aspect ratio and large magnetic leakage at the end, there is a large deviation when using traditional 2-D FEM or an analytical method to analyze and calculate field and torque values for an MRMG. In this article, a 3-D mathematical analytical model of the MRMG eccentric air-gap magnetic field and electromagnetic torque is established, which is suitable for computer modeling. First, based on the cylindrical coordinate system of the inner and outer permanent magnet rings, the 3-D analytical models of the air-gap magnetic field of the inner and outer permanent magnet rings are established, respectively, by using the vector magnetic potential method. Then, by analyzing the position relationship between the inner and outer permanent magnet rings and their superposition angles, the radial and tangential air-gap magnetic fields of the inner and outer permanent magnet rings are superimposed according to their included angles, and a 3-D analytical model of the air-gap magnetic field and the electromagnetic torque of an MRMG is established. Because all the calculations are magnetic field integrals along the axial length of the MRMG, the magnetic field’s end effect is included in the established model, and the calculated results are more accurate than those of a 2-D FEM and analytical method (error >13%). A 3-D FEM and static loading experiment show that the model has a good accuracy (error < 2%) with the measured results and finite-element analysis, but the calculation speed of the model is faster than that of the 3-D FEM, which not only greatly shortens the calculation time but is also suitable for computer programming and is easily used to perform the MRMG analysis and optimization of different MRMG structural parameters.

Evaluation of rockburst energy capacity for the design of rock support systems for different tunnel geometries at El Teniente copper mine

Rockburst events have been a serious problem for many years in many mines worldwide, and in particular at El Teniente mine in Chile. El Teniente is the largest copper mine in the world, located in the Andes Cordillera where high stress levels are present due to intensing mining activity in addition to complex geology. Consequently, the study and management of the rockburst threat are necessary. In this work, the case of the Diablo Regimiento (DR) mine within El Teniente is studied. The energy capacity of dynamic support systems is determined for different tunnel geometries based on two kinetic methodologies, using data from DR. Initially, rockburst potential is determined by means of a stress analysis around different tunnel geometries through the boundary elements method. In the first methodology a yielding zone (YZ) is estimated for each excavation geometry using the finite element method FEM. The second methodology involves the definition and determination of a critical strain energy (SE) around each excavation geometry using a FEM numerical analysis. In both cases, peak particle velocity PPV is estimated by a scaling law, which is subsequently adjusted due to tunnel amplification effects. According to the results, and knowing the working energy capacity applied in DR mine, it was found that the values of energy capacity for the rock dynamic supports were better estimated by the YZ-PPV approach than by the SE approach.

Retardation effect on sheet steel under a mixed I–II mode overload revealed by experiment, DIC and FEM methods

As a high strength and commercial steel, Q420 is widely employed in many engineering applications. In this paper, a series of experiments was conducted to investigate the fatigue crack growth retardation mechanisms under mixed I–II mode overloads with loading angles 0, 30, 60 and 90°. The baseline of loading spectrum is a pure mode I cyclic loading with a mixed overload applied after pre-cracking. The results show that the crack path is always straight for each case. Both the retardation level and fatigue life decrease with the increasing loading angle. A combined model that considers the residual stress, plasticity-induced and roughness-induced crack closure effects was proposed to predict the fatigue crack growth rate and fatigue life. The predicted results agree well with several experimental results.

Second law analysis of a 3D magnetic buoyancy-driven flow of hybrid nanofluid inside a wavy cubical cavity partially filled with porous layer and non-Newtonian layer

The current paper presents numerical results of the 3D buoyancy-driven flow of a hybrid nanofluid in a cubical cavity in the presence of a magnetic field. The computational domain comprises two layers: a non-Newtonian fluid layer and a hybrid nanofluid layer. The temperature disparity within the domain results from heating the wavy bottom wall and cooling both sidewalls while the top wall is insulated. A magnetic field is applied on the positive z-axis. To encounter the non-Newtonian layer influence, the power-law model is considered. The solution of the governing equations is obtained by the Galerkin FEM method. The effects of geometrical parameters of the problem are discussed and illustrated. The results indicate that by simultaneously using non-Newtonian Fe3O4/MWCNT hybrid nanofluid and porous media, the heat exchange in the 3-D cavity is positively affected by the growth in Rayleigh number, Darcy number as well as the height of the porous layer. Furthermore, it is negatively affected by the rise of the magnetic field, corrugation number, and a minor degree when the flow index n was increased due to the pseudo-plastic fluid's high viscosity and shear force.

Analysis of variance dimension of reinforcement to stress concentration factor using Finite Element Method

Stress concentration is a condition when stress increases only at a certain area of a component compared to the stress at the uniform cross-section of the component when given a load. This phenomenon can occur due to irregular geometry such as a hole, sharp angle, cross-section change, notch, threads, groove, crack, etc. Any change in geometric shape on a uniform cross section will cause a stress increases. High stress concentrations need to be reduced to prevent faster failure of a component. The stress concentration that occurs can be determined by using stress concentration factors (Kt). Using FEM method, the simulation obtained stress distribution that occurs in the shaft that is modelled, both without and with the additional groove. The results obtained by the additional of a semi-circular groove can reduce stress concentrations up to ten percent.

Analysis of thin wall cells made of Zhermack silicone rubber used for lower limb prosthesis

The suspension system of the lower limb prosthesis has the main role of providing the permanent contact with the stump. The paper proposed the FEM analysis and the experimental study on the thin wall cells as part of a network inflated with dry air at very well controlled pressure values. The cells are made of bicomponent silicone rubber Zhermack that is biocompatible and has very good elastic properties. The theoretical aspect of this study by using FEM method has computed acceptable values for the Von Misses stress and for the deformation, so that the pressure over the tissue is inside the recommended limits. The designed experimental set-up provides the values for pressure force needed to keep the permanent contact over the entire external surface of the thin wall cell.