Nite Element Research Articles

Study of residual stress-strain behavior of a load-bearing system of a skid-steer loader under multiple loads according to the ROPS safety standard

Introduction (problem statement and relevance). Ensuring safety of road vehicles is a relevant problem. It is particularly applicable to the road construction machinery. The paper presents an algorithm that allows obtaining the most accurate results of calculations according to the procedure described in GOST R ISO 3471 (ROPS): Earth-moving machinery. Roll-over protective structures. Technical requirements and laboratory tests.The purpose of the study is to investigate the stress-strain behavior (SSB) of a structure of a utility platform taking into account residual stresses, strains and relaxation of the structure under multiple loads according to the roll-over safety requirements for earth-moving machinery.Methodology and research methods. The paper presents a skid-steer loader cabin model created in a fi nite element analysis program to perform the strength calculations. The comparative assessment was performed based on the results of a full-scale experiment carried out on a real structure and of virtual simulations. The research object is a skid-steer loader cabin. The research subject is the design methods for vehicle load-bearing structures and their use taking into account operating conditions.Scientific novelty and results. An algorithm has been created which takes into account residual stresses, strains and relaxation of the structure for further loading and allowing reduction of a displacement calculation error for a utility platform from 84.5 to 4.5%. The internal energy reached under vertical load is 426% higher, while for the longitudinal load case it is 14.6% higher, than for the option not taking into account residual stresses and strains.Practical signifi cance. The proposed algorithm allows considering the requirements of GOST R ISO 3471 regarding prevention of structure readjustment or repair between loadings, which is an actual operating mode.

NUMERICAL SOLUTION FOR THE DISTRIBUTION OF THE ELECTROMAGNETIC AND THERMAL FIELDS OF AN AIR-CORE TRANSFORMER

The article presents a numerical solution for the distribution of the electromagnetic and thermal fi elds of an air-core transformer using the fi nite element method. The distribution of the magnetic fi eld is determined for the dynamic steady state and magnetic nonlinear core characteristics. The model presented facilitates the establishment of criteria for optimizing transformer operation under various load conditions, environments as well as in the case of failures. Thus, the transformer can operate at maximum capacity while, at the same time, the probability of faults due to overheating is reduced to a minimum.

Strength calculation of the device for carrying out maintenance and repair of the chassis of fire trucks

The classifi cation is presented and the main designs of pullers designed for maintenance and repair of the chassis of middle class fi re trucks. The design of the puller was proposed, which differs from the existing analogues in smaller dimensions and weight with a constant load in the screw-nut transmission. The development of the device design was based on the use of materials with higher strength characteristics in a friction pair. A three-dimensional model is presented, which shows that the design of the device includes additional mounting holes for changing the confi guration of the grippers, and the puller screw is equipped with two socket wrench heads. The effi ciency of the developed design of the stripper was evaluated by the fi nite element method.

Analysis and Optimization of the Operating Range of a Monopole Antenna Involving ‘Meander’ Type Slot In- homogeneities

Subject and Purpose. The paper presents results of numerical modeling and experimental studies of a disk-shaped microstrip antenna involving ‘meander’ type slotted inhomogeneities. The work has been aimed at optimizing the operating range of the antenna and matching it to external circuits through the use of additional structural elements and appropriate feeding techniques. Methods and Methodology. The design features a circular disk-shaped microstrip resonator containing within its plane groups of slotted inhomogeneities which form a segmented meander line, with the segments oriented relative one another at an angle of 120°. The antenna could be fed through a segment of a screened coplanar line. The location of the screening plane of the coplanar line, as well as its dimensions, were variable. Numerical simulation was carried out within the ‘semi-open resonator’ technique using the finite element method. The degree of optimization of the operating range was estimated, based on analyzing spectral characteristics of the antenna, for a variety of its geometric parameters, and the magnitude of the return loss over a given frequency range. Measurements of the VSWR were carried out with reflectometers. Results. Frequency and power characteristics of a monopole, disk-shaped microstrip antenna have been analyzed and optimized over a wide frequency range. Mechanical dimensions of the additional shielding plane and location thereof have been identified as factors having significant influence upon the frequency-dependent, polarizational and power characteristics of the antenna. Conclusions. The operating frequency range, spectral and power characteristics of a monopole, disk-shaped microstrip antenna have been studied both theoretically and experimentally. Numerical simulations were carried out with the use of the fi nite element method. Experimental studies of the frequency characteristics were performed using reflectometry techniques. The antenna considered can find practical application over a wide frequency range, either as a single radiating element in a device or system, or a constituent part of an antenna array.

Determination of stress-deformed state of complex-shaped basic parts by finite element method and electrotensometry

This article presents a methodology for assessing the stress-strain state using the fi nite element method and using electric strain gauge. The error was determined when comparing the results. The concept of application of a system for monitoring and diagnosing the state of basic parts of heavy engineering objects is described.

ON THE EFFECTIVENESS OF OBLIQUE CAISSON REINFORCED CONCRETE FLOORS

The distribution of forces in the beams of a straight and oblique monolithic reinforced concrete caisson fl oor of a square plan is compared. The forces in the beams are determined by well-known analytical methods and using fi nite element models of the SCAD PC. The calculations showed that the forces in the beams of the oblique caisson fl oor, determined analytically and using computer models, diff er signifi cantly, which indicates the complex operation of the spatial system, which is not taken into account by the analytical calculation method based on the theory of calculating plates supported by the contour. The obtained data indicate that a square caisson fl oor with beams installed at an angle of 450 to the reference contour has greater rigidity and lower values of bending moments compared to straight caissons. When the ratio of the sides of the overlap L2 1,5 . L1 to ensure the eff ect of supporting the contour, the location of the beams in relation to the outer contour should be at an angle of 45.

FEATURES OF THE STRAIN-STRESS STATE OF BEAMS WITH A CORRUGATED WALL OF VARIABLE RIGIDITY

Corrugated steel beams represent a promising area of research in the fi eld of structural engineering today. The article studies the behavior of a metal beam with a corrugated wall of an I-profi le under bending conditions. Beam considered span of 12 m. A fi nite element model of the calculated structure was built in the LIRA-SAPR software package. The analysis of the stress-strain state of a corrugated beam of variable stiff ness, which has a fl at fragment in the central part of the wall, is carried out. The beam thus obtained has a number of advantages over beams with only a fl at or fully corrugated wall. The conclusions based on the results of the analysis of the calculation are presented.

MODELING OF STRESS-DEFORMED STATE OF BENDED REINFORCED CONCRETE ELEMENTS IN ZONES OF CLEAN AND TRANSVERSE BEND

The article deals with the analysis of the stress-strain state (SSS) of a bent reinforced concrete element in zones of pure and transverse bending. It is assumed that a bent element in the process of loading (after the formation of normal and oblique cracks) is divided into blocks, united by uncracked concrete and reinforcement that has adhesion to concrete. SSS was formed using the results of experimental studies of special prototypes in the PC “Lira-SAPR”. A fi nite element model of a prototype has been developed in the form of a reinforced concrete rectangular beam loaded with two identical concentrated forces in the span. By the method of successive approximations, the process of formation and formation of a system of cracks is realized, with which the beam is divided into blocks during loading. The results of calculating the fi nite element model and their comparison with experimental data are presented.

Тепловая модель асинхронного тягового электродвигателя тепловоза

Objective: Evaluation of the temperature regime of the windings of an asynchronous traction electric motor with a squirrel-cage rotor (ATED) of the DAT-350 type of a 2TE25A diesel locomotive using the de- Современные технологии – транспорту 467 ISSN 1815-588Х. Известия ПГУПС 2021/4 veloped thermal model. Methods: The research was carried out by the fi nite element method in the application for calculating steady-state temperature fi elds SolidWorks. Resuls: To ensure the specifi ed service life of the ATED, the temperature rise of the windings must be limited to safe values, based on the insulation class. Therefore, it is crucial that designers and operators have access to accurate and computati onally effi cient, physics-based ATED thermal behavior modeling tools. Practical results: Using the proposed methods, it is possible to accurately and effectively evaluate the thermal characteristics of ATED of promising diesel locomotives. In addition, designers can easily and quickly adjust the parameters and performance characteristics of the ATED in such a way that they are conducive to improving the overall performance of the locomotive.

Finite element method in computer simulation for improved patient care in dentistry: A systematic review

Background. The fi nite element method is gaining acknowledgment in Russia and other developed countries in a range of areas, including medicine. In stomatology, the method is applicable in research and implication of novel treatment and relevant material design.Objective. The review highlights usage of the fi nite element method in computer simulation to improve quality of patient dental care.Methods. The review analyses the state-of-the-art in current scientific literature. Records were mined in the PubMed and e-Library databases at a depth of 10 years, with selective inclusion of earlier articles. The query keywords were: finite element method [метод конечных элементов], computer simulation [компьютерная симуляция], quality of life improvement [повышение качества жизни], oral diseases [заболевания полости рта], dental treatment [стоматологическое лечение].Results. The review systematically surveys 56 scientific papers in the focus area for current state-of-the-art in the finite element analysis-empowered simulation in dentistry. The method’s rising employment is conditioned by its flexibility, 3D-object modelling simplicity and the rapid acquisition of reliable high-quality output. Its undoubted paramount advantage in dentistry is an explicit software visualisation of reliable results through co-modelling of multiple oral parameters.Conclusion. The growing acquaintance, mastering and use of this technique among researchers around the globe will give impetus to novel diagnosis and treatment, as well as relevant management algorithms in particular patient categories to enable personalisation of even mass dental check-up. This will reduce the number of visits, peri- and posttreatment error and complication rates for the improved patient’s quality of life and social rehabilitation.

FINITE ELEMENT ANALYSIS OF ROOT RESORPTION ASSOCIATED WITH TOOTH MOVEMENT: A SYSTEMATIC REVIEW”

Background: The purpose of this systematic review was to examine the available evidence of root resorption during orthodontic treatment with different force systems using nite element analysis. Methods: The following electronic databases were searched for literature till June 2021 : Pro-Quest Dissertation Abstracts and Thesis database, Cochrane Central Register of Controlled Trials (CENTRAL), PubMed, Google Scholar, Embase, US National Library of Medicine, and National Research Register. Root resorption studied under orthodontic forces, which simulated under various technique of nite element method (3D FEM) models were included in the study. The selected studies were assessed for the risk of bias using the Cochrane Collaboration risk of bias tool. The “trafc plot” and “weighted plot” risk of bias distribution were designed using the ROBVIS tool. The authors extracted and analyzed the data. Results: Fourteen studies fullled the inclusion criteria. The risks of biases were high for all studies.Data on quantity and direction of force applied, different type of root morphology and its various surface inuence on root resorption were extracted. The outcomes of the included studies were heterogeneous. Conclusion: Based on the current available literature, for reducing root resorption the excessive force may accelerate root resorption when it exceeds the typical human capillary blood pressure. Root resorption occurs more when extrusion/intrusion and tipping occur than when teeth actually move. A tooth with little or no orthodontic force load hardly shows any root resorption compared to one that has orthodontic force.

NUMERICAL SIMULATION OF SHELL AND TUBE HEAT EXCHANGER IN ANSYSFLUENT SOFTWARE

Numerical modeling of a water-to-water shell-and-tube heat exchanger using the capabilities of mathematical modeling by means of a fi nite element analysis package is considered. An algorithm for solving problems of heat and mass transfer in the ANSYSFluent software product is proposed. A distinctive feature of this algorithm is the simplicity and accuracy of the calculations. In the course of the study, the contours of the velocity and temperature distribution in the heat exchanger were obtained, and the data obtained using computer modeling were verifi ed with an analytical solution.

О ПРОВЕРКЕ ГИПОТЕЗЫ КОСИНУСНОГО РАСПРЕДЕЛЕНИЯ НАПРЯЖЕНИЙ В КОНТАКТЕ «ВАЛ-ОТВЕРСТИЕ»

One of the most common connection types in mechanical engineering and construction is the shaft-hole connection. The mechanical stresses caused by its loading are distributed in the contact zone of the loaded parts of the joint. In some cases, they can lead to destruction. Therefore, while designing, it is important to analyze the mechanical stresses in the contact zone. Traditionally, calculations assume that the contact stresses are distributed according to the cosine law. However, this is not entirely true, especially with diff erent shaft and hole diameters. The authors examined theoretical studies of the contact zone of the shaft and the hole (including the cases of diff erent diameters) and the stress distribution in the contact zone. Based on the studies, they performed numerical calculations in the APMWinMachine environment to determine the stresses in the volume of the shaft and the plate with a hole when loading the shaft-hole connection. The analyses were performed for the two-dimensional case by the fi nite element method in the APMStructure program. The results show that when the diameters in the connection are equal, the stress distribution is close to the cosine law. In this case, only one stress raiser occurs in the contact zone, which is located on the line of action of the loading force. However, if there is a slight discrepancy in the shaft and hole diameters, there are three stress raisers in which the connection may break – the central zone and two side zones. The angular distance between them can be determined based on the known theoretical formulas. The authors made an experiment with a plexiglass model, which qualitatively confi rmed the correctness of the analysis performed.

Convergence and Superconvergence of Fully Discrete Finite Element for Time Fractional Optimal Control Problems

In this paper, we consider a fully discrete finite element approximation for time fractional optimal control problems. The state and adjoint state are approximated by triangular linear fi nite elements in space and L1 scheme in time. The control is obtained by the variational discretization technique. The main purpose of this work is to derive the convergence and superconvergence. A numerical example is presented to validate our theoretical results.

МЕТОДИКА МОДЕЛИРОВАНИЯ И РАСЧЕТА ЖЕЛЕЗОБЕТОННЫХ КОНСТРУКЦИЙ ЭКСПЛУАТИРУЕМЫХ ГТС, УСИЛЕННЫХ ПРЕДВАРИТЕЛЬНО НАПРЯЖЕННОЙ БАЗАЛЬТОКОМПОЗИТНОЙ АРМАТУРОЙ

The development of a methodology for numerical modeling and calculation of reinforced concrete structures of operated hydraulic structures, reinforced with prestressed basalt composite reinforcement, including on the basis of experimental research data carried out in the branch of JSC“Institute Hydroproject”-“NIIES” is presented. Computational studies were carried out on the basis of spatial fi nite element models in the framework of the ANSYS software package. Developing the models, the results of experimental and theoretical studies of hydrotechnical reinforced concrete structures were used in which prestressed basalt composite reinforcement is placed both in the tensioned and compressed zones of the structures.

A new way to identify thin sheet behaviour: Micro-InDef

Incremental forming is a rapid prototyping process which uses a forming tool toform a sheet metal according to a predetermined trajectory. In this work, a micro incremental deformation test (Micro InDef test) derived from the principle of single point incremental sheet forming is developed and proposed. A complex mechanical loading is applied and has a strong potential for the identication of inelastic behavior using inverse method. In the rst part, this work addresses the parameters identication and validation procedures of ductile damage behavior of ultra-thin sheet metal under very large strain during this instrumented Micro InDef test. An inverse nite element method based on the comparison between numerical and experimental axial forming forces of the micro incremental deformation test is employed to extract a coupled ductile damaged plastic model. In the second part, the objective is to prove the reliability of ductile damage parameters identication using forming force. The richness of data contained in forming force is quantied and compared to the one from tensile test. Firstly, the verication of the estimated parameter's reliability is done via a simple analysis based on the forming force sensitivity to material parameters and secondly by calculating elastoplastic and elastoplastic with ductile damage.

Estimation of square die backward extrusion forces of bar stock

Тhe results for estimation of the square die extrusion forces of cylindrical billets are presented. The study is performed on the basis of the fi nite element method. The results obtained during the simulation are analyzed statistically. Regression dependences for forces are obtained, with the help of which reverse extrusion studies are performed.

Optimization of Steel Storage Rack Column and Its Performance Analysis

The main aim of the project is to perform a finite element analysis on steel storage columns. Rack systems for pallet storage are important industrial structures by number and commercial value, yet they have been considered only recently in studies aiming at defining practical design rules for their safe use. These structures are always composed of metal elements. The fabrication of rack structures constitutes, indeed, an important application of cold-formed steel products. The need for continuously loading and unloading the shelves in service has induced designers to avoid bracing elements in the longitudinal direction of the racks. Therefore in many cases, lateral stability in this direction is ensured only by the connections between beam and column and by the constraint offered by the base of the columns. ANSYS used for the model development and analysis presented in this paper. The main requirements for a ?nite element (FE) model of storage rack frames is to have the ?exibility to represent the complex cross-section geometries of the members, and the ability to assign semi-rigid behavior to joints and to take into account the effect of local, distortion and ?exural-torsional buckling in determining the ultimate capacity of the structure and optimization.

Numerical modelling and vibration analysis of human middle ear for application in sound conduction reconstruction

In this paper, we introduce a new numerical approach for estimating the hearing restoration eect prior to the tympanoplasty operation using the nite element harmonic vibration analysis. This kind of approach makes it possible to propose a new medical treatment for the recovery of conductive or cochlear hearing loss. First of all, precise geometric models of the middle ear, including healthy type model and tympanoplasty type models, are constructed on the basis of the computerized tomography (CT) scanning data. Then, frequency response characteristics of the stapes displacement in sound conduction are claried using the three-dimensional nite element harmonic vibration analysis. Based on the investigation results, we propose that the hearing restoration eect can be estimated by a comparison of the dierences in the stapes displacement between the reconstruction model and the healthy subject.

Seismic Behavior of Masonry Cloister Vaults

This paper presents the results of an investigation into earthquake resistance and the behavior of historical masonry cloister vaults. In a previous paper, 1 the authors presented a simpli ed structural analysis approach, called the “strip method of analysis,” to assess the lateral load behavior of a relatively shallow cloister vault. In this paper, two cloister vaults with the same span but with different crown heights are stud- ied. The vault material is assumed to be elastic and a linear thin shell F.E.A. is used for analysis under gravity loads and seismic loads. Nodal reaction components and diaphragm shears are compared for the two cloister vaults, along with those obtained using the strip method of anal- ysis. A compression surface is determined for a selected nite element strip based on in-plane compression forces and out-of-plane bending moments. This is to indicate where tensile stresses will develop due to bending and hence where the vault will develop cracking and go into a limit state. The results include contour plots of membrane stresses, shear stresses, bending stresses and deformations in the masonry cloister vaults under gravity and lateral loads, as well as a representa- tion of the lateral load resistance mechanism of masonry cloister vaults when subjected to earthquakes.