Simulação numérica através do método dos elementos finitos e comparação experimental para obtenção de tensões e deformações específicas em fêmur com prótese total de quadril

Pós-graduação em Engenharia Mecânica - FEG

Nonlinear formulation based on FEM, Mazars damage criterion and Fick's law applied to failure assessment of reinforced concrete structures subjected to chloride ingress and reinforcements corrosion

Structural durability is an important design criterion, which must be assessed for every type of structure. In this regard, especial attention must be addressed to the durability of reinforced concrete (RC) structures. When RC structures are located in aggressive environments, its durability is strongly reduced by physical/chemical/mechanical processes that trigger the corrosion of reinforcements. Among these processes, the diffusion of chlorides is recognized as one of major responsible of corrosion phenomenon start. To accurate modelling the corrosion of reinforcements and to assess the durability of RC structures, a mechanical model that accounts realistically for both concrete and steel mechanical behaviour must be considered. In this context, this study presents a numerical nonlinear formulation based on the finite element method applied to structural analysis of RC structures subjected to chloride penetration and reinforcements corrosion. The physical nonlinearity of concrete is described by Mazars damage model whereas for reinforcements elastoplastic criteria are adopted. The steel loss along time due to corrosion is modelled using an empirical approach presented in literature and the chloride concentration growth along structural cover is represented by Fick's law. The proposed model is applied to analysis of bended structures. The results obtained by the proposed numerical approach are compared to responses available in literature in order to illustrate the evolution of structural resistant load after corrosion start. (C) 2014 Elsevier Ltd. All rights reserved.

The influence of self-weight of elastic 2D structures in topology optimization via numerical technique Smooth Evolutionary Structural Optimization (SESO)

This paper deals with topology optimization in plane elastic-linear problems considering the influence of the self weight in efforts in structural elements. For this purpose it is used a numerical technique called SESO (Smooth ESO), which is based on the procedure for progressive decrease of the inefficient stiffness element contribution at lower stresses until he has no more influence. The SESO is applied with the finite element method and is utilized a triangular finite element and high order. This paper extends the technique SESO for application its self weight where the program, in computing the volume and specific weight, automatically generates a concentrated equivalent force to each node of the element. The evaluation is finalized with the definition of a model of strut-and-tie resulting in regions of stress concentration. Examples are presented with optimum topology structures obtaining optimal settings. (C) 2012 CIMNE (Universitat Politecnica de Catalunya). Published by Elsevier Espana, S.L.U. All rights reserved.

Análise e redução de custos e peso em veículo rodoviário de carga reboque linha de eixos

Load transportation in brazilian territory is made difficult by a deficient highway network, result of low maintenance and lack of government supervision. The problem aggravates when we consider the transportation of indivisible loads, mainly because the brazilian highways are not prepared for such task and few companies in Brazil have the necessary equipment suited for this kind of transport. In this dissertation it will be shown the analysis of a specific equipment to transport overweight indivisible loads, called hydraulic modular multi axle trailer. From an existing project (RB.04LE-01), manufactured and homologated in Brazil, it has been studied how the components in this trailer work so it could have been possible to elaborate a new model (RB.04LE-02), with two main objectives: reduction of costs and weight with subsequent increase in the liquid load for roadway transportation. The trailer’s components analyses were made utilizing the theory of fatigue strength of materials and finite element method with the von Misses criteria for a more safety when realizing the calculations

Análise crítica de um vaso de pressão do setor sucroalcooleiro

This study aims to evaluate structurally a heat exchanger that has been in operation since the mid-60's and was built COSAN for operation in one of its sugar production plants in São Paulo, this equipment as well as many similar devices are operation in plants throughout Brazil, and thus to be acquired by large corporations as in the case of COSAN, pass the scrutiny of inspection work, and work such as recalculations in the latter case in structural evaluations to verify the possible need for adjustments to project or operation and thus ensure the structural integrity of the equipment. To this were first done field survey using techniques of NDT and NDT's for determining the thickness of the main parts of the equipment, made the revaluation dimensional and existing project and considering the loads operating performing the characterization of the equipment as specified in the standard regulatory number 13 - NR13 and the other for this type of equipment and finally an analysis using a static approach, as an analysis tool using the finite element method

Análise estrutural de Tie-Rod pelo método dos elementos finitos e através de cálculos analíticos

Currently one of the great concerns of the aeronautical industry is in relation to the security and integrity of the aircraft and its equipments / components when under critical flight maneuvers such as during landing / takeoff and emergency maneuvers. The engineers, technicians and scientists are constantly developing new techniques and theories to reduce the design time and testing, ir order to minimize costs. More and more the Finite Element Method is used in the structural analysis of a project as well as theories based on experimental results. This work aimed to estimate the critical load to failure for tensile, compression and buckling of the Tie-Rod, a fixture aircraft widely used on commercial aircrafts. The analysis was performed by finite element method with the assistance of software and by analytical calculations. The results showed that the Finite Element Method provides relative accuracy and convenience in the calculations, indicating critical load values slightly lower than those found analytically for tension and compression. For buckling, the Finite Element Method indicates a critical load very similar to that found analytically following empirical theories, while Euler's theory results in a slightly higher value. The highest risk is to fail by buckling, but the geometric irregularity of Tie-Rod pieces makes difficult the calculations, therefore a practical test must be done before validation of the results

Estudo de placas com várias condições de contorno e de carregamento através do método dos elementos de contorno

Even today tables are used in the calculation of structures formed by flat elements, these methods are acceptable only for a limited number of cases, but even so, in some situations, tables are used. With time some methods of differential equations resolutions were emerging and accepted as the most effective solution. Today, with the advancement in technology, there are already some programs able to solve more complex problems in less time using these methods. Aiming to optimize time and better understand the physical behavior of plates, this work presents the theory of plate, the Boundary Element Method (BEM) applied to solve problems of plates (slabs) with various boundary conditions and load through the program Placas2 (TAGUTI, Y.-2010) in Fortran language

Avaliação das condições de contorno da teoria de Hertz, comparando os resultados analíticos e numéricos a partir de simulações em software de elementos finitos

The objective of this study was to present the comparison between analytical and numerical results trying to identify the differences and behaviors of the variation of the principal stresses and the maximum contact pressure for different model configurations. The analytical equations of the theory of Hertz from the boundary conditions adopted by him were differences are shown. A step-by-step of developing the model indicating the geometric dimensions, surface contact, type of contact, the formulation used by the software, type of mesh, as well as the boundary conditions and load was presented. In the results, the stresses calculated analytically and compared with the stresses obtained by the finite element simulation software indicating the changes have been made

Simulação numérica de fluxo de águas subterrâneas na bacia do Rio Grande (BA)

The Urucuia Aquifer System represents a strategic water source in western Bahia. Its baseflow is responsible for the flow rate of the main tributaries of São Francisco river left bank in the dry season, including the Rio Grande, its main tributary in Bahia state. This river has a hydrological regime heavily affected by groundwater and is located in a region with conflicts about water resources. The aquifers geology is constituted by neocretacious sandstones of Urucuia Group subdivided in Posse Formation and Serra das Araras Formation. The embasement is formed by neoproterozoic rocks of Bambuí Group. This work focuses on an important tool application, the mathematical model, whose function is represent approximately and suitably the reality so that can assist in different scenarios simulations and make predictions. Many studies developed in this basin provided the conceptual model basis including a full free aquifer, lithological and hydraulical homogeneity in entire basin, null flux at plateau borders and aquifer base. The finite element method is the numerical method used and FEFLOW the computational algorithm. The simulated area was discretized in a single layer with 27.357,6 km² (314.432 elements and 320.452 nodes) totaling a 4.249,89 km³ volume. Were utilized 21 observation wells from CERB to calibrate the model. The terrain topography was obtained by SRTM data and the impermeable base was generated by interpolation of descriptive profiles from wells and electric vertical drilling from previous studies. Works in this area obtained mean recharge rates varying approximately from 20% to 25% of average precipitation, thus the values of model recharge zones varying in this range. Were distributed 4 hydraulic conductivity zones: (K1) west zone with K=6x10-5 m/s; (K2) center-east zone with K=3x10-4 m/s; (K3) far east zone with K=5x10-4 m/s; e (K4) east-north zone with K=1x10-5 m/s. Thereby was incorporated to the final conceptual model...

Análise de cilindros de paredes grossas através do método dos elementos finitos

Have long studied the distribution of stresses in the cylinder. When this thickness is less than or equal to 10% of the inner radius is possible to consider a uniform distribution along the thickness of the tube. However, when the thickness is greater than 10% of the inner radius is necessary to consider the theory of thick-walled cylinders. This theory shows that when the thickness increases on the radius, the stresses do not act uniformly. The objective of this study is to determine the maximum stresses in thick-walled cylinders by comparing the results obtained by the theory of elasticity and the finite element method

Otimização do braço inferior da suspensão dianteira do veículo Baja utilizando o método dos elementos finitos

Mass reduction coupled with the mechanical performance in service has been the goal of many projects related to the transport area, considering the advantages that mass reduction can bring. However, make a simple material substitution without design a new geometry to corroborate for the best component performance, often makes the replacement unviable. In this study, it was investigated the advantages of replacing the prototype BAJA SAE front suspension lower arm of Equipe Piratas do Vale de BAJA SAE - Universidade Paulista, Campus Guaratinguetá, actually produced with steel, for a new component made of carbon fiber composite. The new geometry has been developed to provide the best possible performance for this component and your easy manufacturing. The study was done using the 3D modeling tools and computer simulations via finite element method. The first stage of this work consisted on calculation of the estimated maximum contact force tire / soil in a prototype landing after jump at one meter high, drop test in the laboratory with the current vehicle, current front suspension lower arm 3D modeling, finite element simulation and analysis of critical regions. After all current component analysis, a new geometry for the part in study was designed and simulated in order to reduce the component mass and provide a technological innovation using composite materials. With this work it was possible to obtain a theoretical component mass reduction of 25,15% maintaining the mechanical strength necessary for the appropriated component performance when incited

Modelagem em 3D de uma patela humana e análise de esforços utilizando o método dos elementos finitos

Throughout the history of medicine surgeons realized the importance of the patella to the functioning of the knee. The main function of the patella is to increase the mechanical efficiency of the quadriceps tendon and knee extensor mechanism. It was found that 50% to 80% of the fractures without deviation of the patella have the transversal pattern, possibly due to excessive tensile forces applied to the extensor mechanism. The purpose of this study is to analyze the loads to which a patella is submitted during a normal extension movement of knee. This analysis will be done by modeling a 3D patella and subsequent load simulation as, described in medical literature, using the finite element method

Estudo de uma ponte rolante comercial no transportede bobina de aço de 12 toneladas

This work aims to determine the stresses acting on the main beam of a crane to transport steel coils of up to twelve tons. To determine the stress it was made a revision of the knowledge of the mechanics of materials to apply the analytical method. Following a review of the finite element method is made to understand the same. To complete the study it was used the commercial software ANSYS to determine the stresses by finite element method, the program provides images that help to better understand the results obtained. With the results a comparison of the values of the tensions between the two methods (analytical and finite element) was made. To assist in the calculations it was used the NBR 8400, 1984 (Calculation of Lifting Equipment Load)

Concentração de tensões em peças e componentes estruturais - uma abordagem através do método dos elementos finitos

Any failure process that may occur in a part probably is located where the stress exceeded the level of resistance. When a part or component has a sharp change in geometry, such as slots, holes, grooves, bumps or other irregularities, there is an increased concentration of stress at a specific location of the part. The objective of this study is to determine the maximum stresses in structural parts and components using the equations of elasticity theory in conjunction with the stress concentration factor experiment and compare them with results obtained by finite element method

Análise estrutural de treliças espaciais no software Excel utilizando o médodo dos elementos finitos

The following paper means to develop a program to make structural analysis of space trusses. The program to be implemented was based on the concepts of the finite element method and used the programing resources of Visual Basic for Applications (VBA) for the Excel Software®. Being Excel® a software of easy access, low cost, capacity to make matrix calculations and with advanced resources of VBA programing, it is possible to develop an economic solution, efficient and precise for structural analysis of space trusses. Firstly is presented a finite elemento method and the space truss. Then is developed a few important algorithms to be used during the development of the program and also the use of a few resources of VBA. And to validate the quality, efficiency and precision of the results, these are compared with the established commercial software Ansys