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

Distribuição de tensões em bocais de vasos de pressão

This work is to analyze the behavior of context concentrated stresses generated around a nozzle connected to a pressure vessel. For this analysis we used the finite element method via a computer interface, the software ANSYS WORKBENCH. It was first necessary to study and intensive training of the software used, and also a study of the ASME Code, Section VIII, which is responsible for the standards used in pressure vessels. We analyzed three cases, which differ primarily in the variation of the diameter of the nozzle in order to analyze the variation of the stresses according to the variation of the diameters. The nozzle diameters were 35, 75 and 105 mm. After the model designed vessel, a pressure was applied on the innervessel of 0.5 MPa. For the smallest diameter, was found the lowest tensions concentrated. Varying between 1 and 223 MPa. Increasing the diameter of the nozzle resulted in increased tensions concentrated around the junction nozzle /vessel. The maximum stresses increased by 78% when the value was increased in diameter from 35 to 75 mm. Since the increase in diameter from 75 to 105 mm, the values of the tensions increased around 43%. These figures emphasize that stress concentrations increased with increasing the diameter of the nozzles, but not linearly

Controle ativo de vibrações em vigas utilizando controle feedforward e elementos espectrais

Pós-graduação em Engenharia Mecânica - FEB

Análise de causas de trincas em carro de translação de empilhadeira/recuperadora

The present work aims to study the possible causes of cracks founded and recovered in translation cars of ore Forklift / ore Reclaimer. To identify the possible causes of cracks observed on the equipment it was used a static approach analysis, using a finite element method as an analysis tool, using a specific structural analysis program. After making the model, a strain gage measurement was necessary because there may be significant amounts of masses of non-structural components that were not modeled and were not available in the drawings, as well as fouling ore. With the calibrated model it was processed analyses with the load cases of dead load, product, wind and excavation. After the processing, it was observed that none of these load cases resulted in values that caused the crack, so another three hypotheses were tested: depression and misalignment, jacking and translation of only three cars. Of these three hypotheses it was observed that the jacking coud be the cause of the cracks, because the distribution of stress. Due to the miss of parameters, like the height utilized in this process, it was not possible to affirm the real stress level

Análise estática de um guindaste de torre, utilizando o método dos elementos finitos

The finite element method is of great importance for the development and analysis of a new product being designed or already on the market, and that requires some specific request or special application. The tower crane, being an essential equipment for modern construction to increase productivity and safety on construction sites, is required for many types of special applications day after day, in many kinds of work. Paying attention to this growing need for handling special projects for the tower crane, faced with the importance and necessity of development and improvement of knowledge in more accurate and practical calculation methods such as the finite element method , for greater agility and precision in the response to a new project. The tower crane is defined by the maximum load moment that it can act with a certain amount of load. The tower crane which will be analyzed in this work , for example, is a tower crane with a resulting capacity of 85 Metric Tons which are considered basic dimensions data of a fisical tower crane of a crane company Liebherr in Guaratinguetá . Thus, the project analysis will begin with the threedimensional representation of the crane lines with AutoCAD software , conversion of this model to the format accepted ANSYS Workbench and completion of 3D modeling of structural components in Design module ANSYS software. After structural modeling is completed, the simulation is performed in static simulation of ANSYS Workbench software mode. The standards will be adopted to DIN (Deutsches Institut für Normung) and EN 14439 (Europäische Normung 14439) and some NR 's related to specific security class of tower cranes, which will be referred throughout the work

Análise estrutural do suporte de pastilha de grafite para lubrificação de roda ferroviária

This study aims to structurally evaluate a support of graphite pastille for the lubrication of railway wheels. The proper lubrication of wheel flanges of the railway extends the life of this component, so it is very important that this occurs lubrication to reduce the costs involved in railway maintenance. To prepar the evaluation structural will be used to International Electrotechnical Comission standard (IEC 61373) establishing which load cases should be applied to this component. The applied loads on the support (accordance with IEC) are random accelerations and accelerations due to shocks, thus simulating the conditions that exist along the route of the train. The structural analyzes are performed by the finite element method, with the aid of the Cosmos software. Thus, it is possible to determine the stresses acting on the support, and so the allowable stresses compared with the standard proposed by the AISC. The stress in the structural analyzes are lower than allowable therefore considered for the configuration presented, unexpected structural problems

Caracterização do fator de intensidade de tensão em corpos trincados através do método dos elementos finitos

The industry generally has sought materials with high mechanical resistance, low density, thermal stability and corrosion resistance. In the aerospace industry, for example, the use of aluminum alloys, such as Al 2024-T351 and Al 7075-T7351, have become essential. However, the use of these materials often do not resulted in a satisfactory performance of the component, since the presence of cracks can cause total rupture of the component, even with a tension below the yield stress of the material, unexpectedly. In this work, these aluminum alloys were analyzed and samples were modeled by the finite element method. Moreover, in the models were applied two different types of cracks, central and edge crack, a vertical force was applied to result in a tension 70% of the yield stress of the material analyzed. Through stress asymptotic distribution in the region near the crack tip were calculated the values of the stress intensity factors for each crack length, after the stress intensity factors characterized were compared graphically with the values of fracture toughness found in the available literature

Controle ativo de estruturas reticuladas utilizando atuadores de pilha de pzt

Pós-graduação em Engenharia Mecânica - FEIS