Nite Element Model Research Articles

Результаты расчетов напряженно-деформированного состояния и устойчивости грунтовой перемычки сухого дока с учетом ее перепрофилирования

The purpose of the work was to determine the stress-strain state, to check the bearing capacity of structures (sheet pile walls, anchor rods) and the overall stability of soil prisms of the «structure-enclosing soil mass» system, taking into account its re-profi ling. According to the scope of work, computational study of the sheet pile wall structure of the excavation under the buttress foundation was performed (specifying the adequacy of the solutions adopted in the drawings for the length and spacing of the tie rods and the bottom marks of the sheet pile walls by section, as well as the struts in the west abutment and the need for geotechnical anchors. The computational studies were carried out with the PLAXIS software package. In the fi nite-element model there were realized: conditions of contact interaction of media; nonlinear and plastic properties of materials; geometrical nonlinearity in the form of staggered erection and sequence of loadings application.

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.

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.

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.

Domain reduction method for seismic analysis of Dam-Foundation-Fault system

Numerical simulation of dam-foundation-fault system, considering the earthquake source, propagation path, and local site e ects, was carried out for realistic and reasonable seismic safety analysis of concrete dams. The Domain Reduction Method (DRM) was used for seismic analysis of Dam-Foundation-Fault (DFF) system, in which a modular two-step methodology for reducing the computational costs in large domain analysis was introduced. In this method, seismic excitation is directly applied to the computational domain such that assigning arti cial boundary to the nite element models is more comfortable. In order to verify the implementation of the DRM in Finite Element Method (FEM), a simple 2D half-space under the Ricker wavelet excitation was examined. Then, to investigate the DRM as an appropriate method in seismic analysis of DFF system, the Koyna concrete gravity dam was modeled. Comparing the obtained results by usingboth the DRM in a small domain and the traditional approach in the large domain containing the source shows the eciency of the DRM in terms of computational costs, such as running time and number of elements for seismic analysis of concrete gravity dams.

STRESS-STRAIN STATE OF ECCENTRICALLY COMPRESSED REINFORCED CONCRETE COLUMNS OF CIRCULAR CROSS-SECTION

Theoretical studies of reinforced concrete eccentrically compressed columns of circular cross-section on strength indexes are analyzed. These studies rely on the use of a nonlinear deformation model that approximates the work of concrete to real experimental conditions. A comparative analysis of the results of calculating the strength of reinforced concrete columns of circular cross-section is carried out according to the methodology proposed in the current set of rules, is the author’s program for determining the stress-strain state of a reinforced concrete column of circular cross-section implemented in the MathCad software environment. The results of a numerical experiment are compared in the form of a fi nite-element model in the Lira-CAD program complex using a nonlinear deformation model. Calculations and schemes are given taking into account the possibility of conducting an experimental study.

STUDIES OF DEFLECTIONS OF STATICALLY DETERMINED REINFORCED CONCRETE BEAMS BASED ON A NONLINEAR DEFORMATION MODEL

In this paper theoretical studies of statically determinated bending reinforced concrete beams of rectangular cross-section on deformation indexes under the eff ect of a short-time uniformly distributed load are viewed. These theoretical studies are based on the main points of the nonlinear deformation model that takes into account the nonlinear work of concrete and fi tments taking into account discrete cracking. The results of calculating the deformation of beams by the method of SP 63.13330.2012 and by authors’ method are proposed as well as the results of a numerical experiment with the identifi cation of the stress-strain state of statically determinated beams in the form of a fi nite element model in the program complex «Lira CAD-2017R3» using a linear and non-linear sett ing of characteristics of concrete and reinforcement. Based on the results of theoretical studies, the calculation results by the methodology of the current standard with a numerical experiment, as well as with the authors’ calculation methodology are compared. All calculations and loading schemes in this technique are given taking into account the possibility of further experimental studies.

Dynamic load testing of a railway masonry arch bridge: A case study of Babak Bridge

Health monitoring of masonry bridges is vital due to their long life in service and an increasing need for higher axle loads. Results of feasibility study of applying an increased axle load of 25 tons to an old masonry bridge are presented in this paper. Babak Bridge is located in north western zone of Iranian railway network and has been in service for more than 70 years. It consists of stone masonry blocks, has three long spans of 21.5 m,7 spans of 10 m, and a total length of 270 m. Response of the bridge subjected to prede ned train loading by 15 sensors, including deflection meters, accelerometers, and strain gauges, is recorded. A total of 37 tests are carried out on Babak Bridge, and the results are used to calibrate the nite-element model of the bridge, which is developed by Abaqus software. The numerical model is then used to determine the weak spots of bridge due to subjection of higher axle loads for a possible strengthening procedure. Ultimate load-carrying capacityof the bridge is also assessed by Ring software, which suggests a minimum adequacy factor of 1.25 for an axle load of 25 tons.

Developing a finite element beam theory for nanocomposite shape memory polymers with application to sustained release of drugs

In this paper, a thermodynamically-consistent constitutive model recently proposed for nanocomposite shape memory polymers (SMPs) is used as a basis for development of SMP beam element in a nite element framework. The beam theory utilized here, is the Euler- Bernoulli beam theory with its basic assumptions. E ects of di erent material as well as the geometric structural parameters e.g., reinforcement (nano/micro-particles) volume fraction, viscosity coecients and external loads are studied on the thermoemchanical responseof the structure in this work. The beam element numerical results are compared to those of 3D nite element modeling, to verify the validity of the beam element formulation andthe assumptions made therein. This beam element provides us a fast and reliable tool in simulation of structures consist of reinforced SMP beams. As an application, the developed nanocomposite SMP beam element could be used for numerical modeling of thermechanical response of the drugs (e.g., theophylline) coated by lms of SMP nanocomposites. It is shown that the numerical results are in correspondence with those of experiments reported for sustained release of SMP-nanocomposite based drugs.

Active faults in the Anatolian-Aegean plate boundary region with Nubia

Convergence of the Africa, Arabia, and Eurasia plates and the westward escape of Anatolia have resulted in an evolving plate boundary zone in the Eastern Mediterranean. e current location and nature of the plate boundary between the Anatolian and the African plate is di cult to trace due to the scattered crustal earthquakes and the absence of deep ones. We examine various types and locations for the plate boundary as constrained by seismicity, seismic re ection studies, tomographic studies, and geodetic measurements and we use a spherical plane stress nite element model to test these possibilities. In our regional model, we impose the convergence of Africa, Arabia, and stable Eurasia by applying GPS-derived velocities in the far- eld, as well as the roll-back of the Hellenic trench to solve for regional deformation. Model velocity and stress elds are compared with GPS-derived velocities and stress directions from focal mechanism solutions. We nd that the plate boundary via the Pliny and Strabo trenches, the Anaximander Mountains, the Eratosthenes Seamount collisional segment, and the Latakia-Larnaka ridges gives the best t to the data. e Anaximander Mountains plate boundary has both down-dip and strike-slip motions, and the Latakia segment is pure strike-slip. e Cyprus subduction contact is 42% locked. From a combined analysis of indicators for long-term deformation (predominantly slip-rates on major faults) and model results we infer that this southern plate boundary con guration may have existed since the Late Pliocene.

BUCKLING OF ANISOTROPIC PLATES BY THE RITZ METHOD

The Ritz method is used in the buckling analysis of anisotropic plates under several combinations of in-plane loads and boundary conditions. Ritz bases are generated from modi ed Legendre polynomials, and the plate rigidities are carefully chosen to provide thermodynamically admissible materials. The accuracy of the proposed approach is assessed by means of several examples solved by nite element models.

A genetic-based model to predict maximum lateral displacement of retaining wall in granular soil

Retaining walls are one of the most common geotechnical structures. Horizontal displacement at the top of the retaining wall is an important parameter in design of retaining structures because of serviceability of the wall and adjacent structures. In this research, the Gene Expression Programming (GEP) is used for developing a model to predict this design parameter of retaining wall. The input parameters of the model consist of e ective period of adjacent structure, horizontal and rocking sti ness of the foundation of adjacent structure, density, Young's modulus, and friction angle of granular soil as well as the thickness and height of retaining wall. The output of the model is maximum lateral displacement of retaining wall. A database including 240 cases, created from 3D nite element modeling of a soil-retaining wall with an adjacent steel structure modeled as surcharge, is employed to develop the model. Comparison of the GEP-based model predictions with the simulated data indicates a very good performance and ability of the developed models in predicting maximum lateral displacement of retaining walls. Sensitivity and parametric analyses are conducted to verify the results. It is shown that soil density is the most in uential parameter in the maximum lateral displacement of retaining wall.

Performance of frp-retrofitted concrete bridge columns under blast loading

Contrary to military or essential government buildings, most bridges are designed without any consideration for blast resistance. Fiber-reinforced polymers (FRPs) can provide an effective means for strengthening of critical bridges against such loading. This study has focused on the effectiveness of FRP retrofi tting in the dynamic response of reinforced concrete bridge columns under blast loading. Using a simplifi ed equivalent I-section with a virtual material lumped at the two fl anges; a lightly meshed uniaxial fi nite element model was developed and successfully validated against previous studies. The proposed model was then used for a thorough parametric study on the blast resistance of bridge substructures in the form of a single-column, two-column pier frame, and an entire bridge. The study showed the benefi ts of strengthening with composites against blast loading. The FRP tensile strength and diameter-to-thickness ratio, steel reinforcement ratio, and column length and damping ratio signifi cantly affect the blast resistance of an FRP-retrofi tted bridge. Finally, based on the parametric study results, predictive equations with multiple linear regression and high order terms were developed statistically for the FRP retrofi t design of single columns against blast loading.

A Research on Structured Analysis of Biomaterial of Dental Implant in Computer Aided Biomechanical Engineering Modelling

The research explained in this paper is about the mechanical principle applications on regulated form and function, forces, motion of teeth and dental implant in uencing the implant length and bone quality in biomechanics engineering modeling in dentistry. The non-linear nite element method was employed as an advanced computer technique of structural stress analysis tool for biomechanics modeling using mechanical, mathematical, and biological de nitions and concepts. A nite element model of dental implant with accurate geometry and material properties was developed to make realistic investigations on the implant biomaterial properties and mechanical behavior of new dental implant. The nite element models with non-linear contact elements were used to simulate an interface xation within the implant system and the sliding function of the non-rigid connector. This research showed that implant design in uences force transmission characteristics in peri-implant bone and mechanical signals a ect bone tissue di erentiation. Hence, it is important to control biomechanical loads on dental implants to maintain osseointegration and to promote early bone implant interface healing. The results of this analysis are helpful for implant biomaterial selection and design for clinical interest.

Shock mitigation for electronic boards within a projectile

Electronic components, which are widely used in modern projectiles, are subjected to high acceleration during launch. These accelerations may result in failure of the components, which affects the performance of the projectile. The objective of this research is to better understand how shocks are transmitted to electronic boards within a projectile and also to investigate ways of mitigating these shocks. To achieve these goals, a projectile prototype, composed of threaded components, was created. The effect of the tightening preload torque on the accelerations and the frequencies of the components on an electronic board were explored. An approach to mitigate transmitted accelerations to the board using a polyurethane rubber mount is presented. Suggestions for ensuring an accurate fi nite element model of the experimental setup are included.

Numerical simulation of the human ear and the dynamic analysis of the middle ear sound transmission

Based on the clinical CT of normal right ear, a 3-D ?nite element (FE) model of the human ear consisting of the external ear canal, middle ear(tympanic membrane, ossicular chain, ligaments, tendons), and inner ear (including semicircular canals, vestibular, spiral cochlear)was constructed in this paper. The complicated structures and inner boundary conditions of middle ear were described in this model. Model analysis and acoustic-structure-?uid coupled dynamic frequency response analysis were conducted on the model. The validity of this model was confirmed by comparing the results with published experimental data. The amplitudes and velocities of tympanic membrane and stapes footplate, sound pressure gain across the middle ear, and the cochlear input impedance were derived. Besides, it was concluded that the ear canal can amplify the sound signal in low frequencies.The modes of vibration of middle ear auditory ossicles, oval window and round window have been analysed. This model can well simulate the acoustic behavior with the interaction of external ear, middle ear and inner ear, which can supply more valuable theoretical support for development and improvement of hearing-aid and artificial inner ear.

Erosion-induced isostatic rebound triggers extension in low convergent mountain ranges

Mechanisms that control seismic activity in low strain rate areas such as western Europe remain poorly understood. For example, in spite of low shortening rates of <0.5 mm/ yr, the Western Alps and the Pyrenees are underlain by moderate but frequent seismicity detectable by instruments. Beneath the elevated part of these mountain ranges, analysis of earthquake focal mechanisms indicates extension, which is commonly interpreted as the result of gravitational collapse. Here we show that erosional processes are the predominant control on present-day deformation and seismicity. We demonstrate, using fi nite element modeling, that erosion induces extension and rock uplift of the elevated region of mountain ranges accommodating relatively low overall convergence. Our results suggest that an erosion rate of ~1 mm/yr can lead to extension in mountain ranges accommodating signifi cant shortening of <3 mm/yr. Based on this study, the seismotectonic framework and seismic hazard assessment for low strain rate areas need to be revisited, because erosion-related earthquakes could increase seismic hazard.

Development of an automated pre-processing tool and case study for coach rollover analysis

Coach rollover numerical simulation is a highly complex and time-consuming process, especially in terms of its pre-processing tasks, which are commonly done manually. To improve modelling effi ciency and standardise the modelling process so as to shorten the computation running time, based on the fi nite element software package Altair HYPERWORKS, an automated process tool is developed using Tool Command Language (TCL). The tool’s framework is proposed as a step-by-step modelling wizard including 12 technical modules in compliance with ECE/R66. Users can easily use the tool without specialised knowledge of rollover simulation process and regulations. Based on the wizard, the complete fi nite element modelling for a coach rollover simulation validates the process tool’s capability in automation and effi ciency. Then a case study of coach rollover is carried out to investigate the rollover scenario and the superstructure strength. Compared to previous pre-processing methods, remarkable time was saved and the modelling process was standardised by utilising the automated process tool, which proved its feasibility and high effi ciency.