The exposure from a localized vehicle fire has been observed to produce excessive damage onto highway bridge structural elements including complete collapse of the infrastructure. The occurrence of a fire beneath a bridge can lead to significant economic expense and loss of service even if the bridge does not collapse. The focus of the current research is to assess and evaluate the effect of realistic localized fire exposures from vehicles on the bridge structural integrity and to guide future development of highway bridge design with improved fire resistance. In this research, the bridge structural element response was predicted through a series of three loosely coupled analyses: fire analysis, thermal analysis, and structural analysis. Two different types of fire modeling methodologies were developed in this research and used to predict the thermo-structural response of bridge structural elements: one to model the non-uniform exposure due to a vehicle fire and another to predict response due to a standard uniform furnace exposure. The vehicle fire scenarios required coupling the computational fluid dynamics (CFD) code Fire Dynamics Simulator (FDS) with Abaqus while the furnace exposure scenarios were all done within Abaqus. Both methodologies were benchmarked against experimental data. Using the developed methodologies, simulations were initially performed to predict the thermo-structural response of a single steel girder-concrete deck composite assembly to different local, non-uniform fires and uniform standard furnace fire exposures. The steel girder-concrete deck composite assembly was selected since it is a common bridge design. Following this, a series of simulations were performed on unprotected highway bridges with multiple steel plate girders and steel tub girders subjected to localized fires. The analyses were used to evaluate the influence of a fire scenario on the bridge element response, identify the factors governing the failure of bridge structural elements subjected to a localized fire exposure, and provide guidance in the design of highway bridge structural elements against fire hazards. This study demonstrates that girder geometry affected both the dynamics of the fire as well as the heat transfer to the bridge structural elements which resulted in a different structural response for the bridge. A heavy goods vehicle (heat release rate of 200 MW) and tanker fires (heat release rate of 300 MW) were predicted to cause the bridge to fail due to collapse, while smaller fires did not. The geometric features of the plate girders caused the girder elements to be exposed to higher heat fluxes from both sides of the girder resulting in collapse when exposed to a HGV fire. Conversely, the closed feature of the box girder does not allow the interior surfaces to be in direct contact with the flames and are only exposed to the internal reradiation from surfaces inside the girder. As a result, the single and double lane tub girder highway bridge structure does not fail due to a heavy goods vehicle fire exposure. / Ph. D.

A comprehensive stress model of the filament winding fabrication process, previously implemented in the finite element program, WACSAFE, was implemented using the ABAQUS finite element software package. This new implementation, referred to as the ABWACSAFE procedure, consists of the ABAQUS software and a pre/postprocessing routine that was developed to prepare necessary ABAQUS input files and process ABAQUS displacement results for stress and strain computation. The ABWACSAFE procedure has a structure and general flow pattern similar to the WACSAFE program. ABAQUS now performs the fundamental finite element procedures needed in the fabrication stress model. The ABWACSAFE pre/postprocessing routine utilizes many subroutines from the WACSAFE program. Some subroutines are used in their original form while many were significantly modified. New subroutines have been written as well. / Master of Science

This research explores the nearly untapped research area of the analysis of fracture mechanics in residual stress zones. This type of research has become more prevalent in the field in recent years due to the increase in prominence of residual stress producing processes. Such processes include additive manufacturing of metals and installation procedures that lead to loads outside the anticipated standard operating load envelope. Abaqus was used to generate models that iteratively advanced toward solving this problem using the compact tensile specimen geometry. The first model developed in this study is a two-dimensional fracture model which then led to the development of an improved three-dimensional fracture model. Both models used linear elastic fracture mechanics to determine the stress intensity factor (K) value. These two models were verified using closed-form equations from linear elastic fracture mechanics. The results of these two models validate the modeling techniques used for future model iterations. The final objective of this research is to develop an elastic-plastic fracture mechanics model. The first step in the development of an elastic-plastic fracture model is a three-dimensional quasi-static model that creates the global macroscale displacement field for the entire specimen geometry. The global model was then used to create a fracture submodel. The submodel utilized the displacement field to reduce the model volume, which allowed a higher mesh density to be applied to the part. The higher mesh density allowed more elements to be allocated to accurately represent the model behavior in the area local to the singularity. The techniques used to create this model were validated either by the linear elastic models or by supplementary dog bone prototype models. The prototype models were run to test model results, such as plastic stress-strain behavior, that were unable to be tested by just the linear elastic models. The elastic-plastic fracture mechanics global quasi-static model was verified using the plastic zone estimate and the fracture submodel resulted in a J-integral value. The two-dimensional linear elastic model was validated within 6% and the three-dimensional linear elastic model was validated within 0.57% of the closed-form solution for linear elastic fracture mechanics. These results validated the modeling techniques. The elastic-plastic fracture mechanics quasi-static global model formed a residual stress zone using a Load-Unload-Reload load sequence. The quasi-static global model had a plastic zone with only a 0.02-inch variation from the analytical estimate of the plastic zone diameter. The quasi-static global model was also verified to exceed the limits of linear elastic fracture mechanics due to the size of the plastic zone in relation to the size of the compact specimen geometry. The difference between the three-dimensional linear elastic fracture model J-integral and the elastic-plastic fracture submodel initial loading J-integral was 3.75%. The J-integral for the reload step was 18% larger than the J-integral for the initial loading step in the elastic-plastic fracture submodel. / Master of Science / Additive manufacturing, sometimes referred to as 3-D printing, has become an area of rapid innovation. Additive manufacturing methods have many benefits such as the ability to produce complex geometries with a single process and a reduction in the amount of waste material. However, a problem with these processes is that very few methods have been created to analyze the initial part stresses caused by the processes used to additive manufacture. Finite element methods are computer-based analyses that can determine the behavior of parts based off prescribed properties, shape, and loading conditions. This research utilizes a standard fracture determination shape to leverage finite element methods. The models determine when a crack will form in a part that has process stresses from additive manufacturing. The model for crack initiation was first developed in two dimensions, neglecting the thickness of the part, using a basic material property definition. The same basic material property definition was next used to develop a crack initiation model in three dimensions. Then a more advanced material property definition was used to capture the impact of additive manufacturing on material properties. This material property definition was first used to establish the part properties as it relates to part weakening due to additive manufacturing. A higher accuracy model of just the crack development area was produced to determine the crack initiation properties of the additive manufactured part. Methods previously confirmed by testing were used to validate the models produced in this research. The models demonstrated that under the same loading parts with initial processes stresses were closer to fracture than parts without initial stresses.

A dynamic simulation of the response of an inflatable dam subjected to a flood was carried out to determine the survivability envelope of the dam where it can operate without rupture, or overflow. A fully nonlinear free-surface flow was applied in two dimensions using a mixed Eulerian-Lagrangian formulation. An ABAQUS finite element model was used to determine the dynamic structural response of the dam. The problem was solved in the time domain which allows the prediction of a number of transient phenomena such as the generation of upstream advancing waves, and dynamic structural collapse. Stresses in the dam material were monitored to determine when rupture occurs. An iterative study was performed to find the service envelope of the dam in terms of the internal pressure and the flood Froude number for two flood depths. It was found that the driving parameter governing failure of the dam was the internal pressure. If this pressure is too low, the dam overflows; if this pressure is too high, the dam ruptures. The fully nonlinear free-surface flow over a semi-circular bottom obstruction was studied numerically in two dimensions using a similar solution formulation as that used in the previous study. A parametric study was performed for a range of values of the depth-based Froude number up to 2.5 and non-dimensional obstacle heights up to 0.9. When wave breaking does not occur, three distinct flow regimes were identified: subcritical, transcritical and supercritical. When breaking occurs it may be of any type: spilling, plunging or surging. In addition, for values of the Froude number close to 1, the upstream solitary waves break. A systematic study was undertaken, to define the boundaries of each type of breaking and non-breaking pattern, and to determine the drag and lift coefficients, free surface profile characteristics and transient behavior. / Master of Science

Yes / The impact behavior of deflection-hardening High Performance Fiber Reinforced Cementitious Concretes (HPFRCs) was evaluated herein. During the preparation of HPFRCs, fiber type and amount, fly ash to Portland cement ratio and aggregate to binder ratio were taken into consideration. HPFRC beams were tested for impact resistance using free-fall drop-weight test. Acceleration, displacement and impact load vs. time graphs were constructed and their relationship to the proposed mixture parameters were evaluated. The paper also aims to present and verify a nonlinear finite element analysis, employing the incremental nonlinear dynamic analysis, concrete damage plasticity model and contact surface between the dropped hammer and test specimen available in ABAQUS. The proposed modelling provides extensive and accurate data on structural behavior, including acceleration, displacement profiles and residual displacement results. Experimental results which are further confirmed by numerical studies show that impact resistance of HPFRC mixtures can be significantly improved by a proper mixture proportioning. In the presence of high amounts of coarse aggregates, fly ash and increased volume of hybrid fibers, impact resistance of fiberless reference specimens can be modified in a way to exhibit relatively smaller displacement results after impact loading without risking the basic mechanical properties and deflection-hardening response with multiple cracking.

The ability of a Formula SAE sports car to negotiate a turn in a race is influenced by many parameters which include car's overall geometry, its shape, weight distribution, type of suspension used, spring and shock absorber characteristics that are used in the tire properties, static and dynamic loading. Steady-state cornering implies that the forces acting on the vehicle are unchanging for a given time. The suspension uprights form a connection between the wheel assembly and the suspension linkages. The criticality of the upright is that it is considered an un-suspended body, but in fact, it is subjected to very high stresses. The dynamic load imposed on the vehicle from various road conditions, cornering, braking and suspension assembly constraints generate stress on the upright body. The equations of motion generally govern vehicle dynamics. For a kinematic and rigid body dynamics analysis, a multibody dynamics (MBD) approach is popular. The results of the dynamic analysis yield internal loads which are used to analyze suspension components for structural stiffness and strength. Automotive companies with relatively lower structural loads have made the MBD approach popular because it is supposed to be computationally less expensive. Elastodynamics is an alternative approach to solving dynamics equations while considering the components to be elastic. This approach can capture the inertial and elastic responses of the components and the load path with varying positions of the components in a mechanism. In this research, a quarter-car suspension is modeled in a finite element code (Abaqus®), focusing on the vehicle upright but still modeling the connections and interactions of the quarter-car suspension system of a FSAE vehicle. The BEAM element modeling used for the suspension members captures the bending response. The overall model is created by making computationally conscious decisions, debugging and refining the interactions and connections to be representative. The modeling technique to create elastodynamic models is explored and established with a versatile set of suspension components and interactions providing a good experience with finite element modeling. The models are created with incremental steps and early steps are verified with hand calculations. A further vehicle verification and validation plan is the next immediate priority to gain confidence in the model for accurate simulations which can be used to predict accurate structural and dynamic results. With extending the model capabilities and computational capabilities, a quarter-car suspension model is powerful enough to run the entire track simulations for formula races and even durability load cases for commercial vehicles. Fatigue loading and abusive test cases would be the load cases to investigate possible failure modes. The quarter-car suspension model is a framework with different interactions, connections, components, boundary conditions and loads that are representative for different suspension configurations in different vehicles. The best practices of this modeling exercise are established and scalability to defeature or add details while preserving the connection behavior is achieved. / Master of Science / Automotive suspension analysis includes analysis the design of suspension components. In automotive parlance, suspension includes the wheel subassembly, brakes, tires, shock absorbers, subframes and the steering system. A quarter-car model is incorporated in this research to analyse a Formula SAE suspension. The quarter-car model is representative of relevant vehicle dynamics within the scope of this research. The suspension of the vehicle governs the “attitude” of the vehicle; it is a foundation on which the behavior of the car is built when it responds to operator wishes and terrain. Necessary but not sufficient for a great car is addressing multiple issues around strength and stiffness of the components during vehicle maneuvers. These issues are pulled against cost and packaging issues as jelly sets for engineering design with only a small number of physical iterations. Finite element analysis employs its powerful solving capabilities to run an elastodynamic simulation. The representation of the component’s elasticity yields elastic responses that can be observed and evaluated virtually for engineering design. Current state-of-the-art methods rely on rigid body analysis to develop dynamic simulations which do not show elastic response or response due to complex interactions between the components. The elastodynamic model built for this research is scalable to include detail or defeatured components without losing their interactions and connection behaviors – examples include – rod end joints, bearing interference fits and bell crank connections for a pull rod suspension. Several finite element modeling practices are established as part of this research to build a popular problem in the automotive industry – quarter-car suspension model. The elastodynamic model is verified along the journey by building simpler building-block models. Further validation of the elastodynamic model is required for complete confidence – the path to which is covered in this thesis.

[pt] A estabilidade de poços através de zonas de sal é um aspecto relevante em ambientes de perfuração offshore no Brasil. O fluxo convencional no planejamento de um poço de petróleo não reconhece a natureza complexa do estado de tensões in-situ em torno destes corpos de sal. Portanto, é necessária uma avaliação fiável das tensões in-situ considerando tanto a escala de campo (global) quanto as principais estruturas presentes no overburden. Neste trabalho, a análise de estabilidade de poços é realizada em três etapas. Primeiro, é realizada uma análise numérica a escala global para avaliar as tensões in-situ considerando a geometria de um corpo de sal. A seguir, são introduzidas as tensões in-situ em um modelo local, chamado subestrutura, através de duas técnicas de transferência de tensões propostas, denominadas as técnicas do Inverso Ponderado da Distância (IPD) e do Gradiente de Tensões (GT). O termo subestrutura é definido como uma linha curva no espaço composta por um conjunto de pontos, se assemelhando a uma seção ou trajetória completa de um poço. Finalmente, a janela operacional do poço é calculada acoplando os resultados de tensões da modelagem numérica com equações elásticas. Neste trabalho as técnicas IPD e GT são também utilizadas para transferir tensões em submodelos localizados dentro de um modelo global, visando realizar futuros estudos de submodelagem de estabilidade de poços. O termo submodelo consiste em uma malha de elementos finitos de um tamanho menor e um refinamento maior em relação ao modelo global. / [en] Wellbore Stability drilling through salt zones is an important current endeavor in many areas offshore of Brazil. The conventional well design workflow does not recognize the complex nature of the stress field near these salt bodies. Therefore, a reliable assessment of the in-situ stresses must be carried out considering a field (global) scale of the problem and the presence of major structures in the overburden. The proposed stability analysis is carried out in three stages. Firstly, a global finite element analysis is employed to evaluate the in-situ stresses at a global scale considering the geometry of a salt body. Secondly, the global scale in-situ stresses are introduced in a local model, that we call substructure, by using two proposed stress transfer techniques called the Inverse Distance Weighted Technique (IDWT) and the Stress Gradient Technique (SGT). We define Substructure as a set of points forming a section or a complete trajectory of an oil well. Finally, optimal mud weights are calculated combining numerical stress results with analytical elastic equations. These two stress transfer techniques are also proposed to be used to transfer stresses to submodels inside a global model domain for submodeling wellbore stability purposes. The term submodel is defined as a finite element mesh with a smaller size relative to the size of the global model.

During the insert process when the windings of an electric motor are pushed into the stator slots, some detrimental phenomena can occur that affect the efficiency and life of the motor. To detect these phenomena and optimize the process, a simulation would be useful. An investigation of the possibility to perform a simulation, using an appropriate numerical method for the insert process of distributed windings in a permanent magnet synchronous motor, was performed. During the project, a literature study was carried out to investigate existing methods and key-parameters for the simulation of the process. Explicit finite element method has been shown to be a suitable numerical method for simulating another winding process. An explicit finite element analysis was performed with a simplified model of the stator, the wires, the transmission tool and the needles by using the software Abaqus/CAE. In order to reduce the computational time, beam elements were used to model the wires and the other parts as rigid bodies. The model accounted for example contact and provided numerical results. The result was a suitable model. However, it needs to be developed further.

O ensaio SPT (Standard Penetration Test), é o ensaio de campo geotécnico mais usado no Brasil e grande parte do mundo. A ampla utilização deste ensaio no âmbito da engenharia geotécnica deve-se à sua simplicidade, baixo custo, grande experiência prática e facilidade de aplicação dos seus resultados. Os principais objetivos do ensaio são a determinação do índice de resistência do solo (NSPT) e amostragem. Apesar de ser muito utilizado na estimativa da capacidade de carga de fundações, o ensaio SPT tem sido questionado pelo fato de que o índice NSPT é utilizado em correlações empíricas baseadas em observações práticas, sem nenhum fundamento científico. Além do mais, seus resultados apresentam significativas dispersões. Para analisar racionalmente os resultados do ensaio e de possibilitar a comparação dos diferentes resultados de distintas equipes, é necessário conhecer as quantidades de energia envolvidas na penetração do amostrador no solo. Tais análises requerem o conhecimento da eficiência do equipamento (η) e a força de reação dinâmica do solo à cravação do amostrador (RD). Neste cenário, o presente trabalho aborda a interpretação racional dos resultados de ensaios SPT a partir de simulações numéricas realizadas com o software Abaqus/Explicit®. Esse programa fornece os deslocamentos do amostrador (Δρ), força de reação dinâmica do solo (RD), e as forças de reação nas paredes laterais externa e interna do amostrador (R1 e R2). Baseando-se nos resultados dos modelos numéricos, foi possível calcular a eficiência do equipamento, a partir da força de reação dinâmica do solo, as resistências unitárias de atrito atuantes nas paredes e a resistência unitária na ponta do amostrador. Também foi possível determinar a relação entre as resistências unitárias de atrito desenvolvidas no interior e exterior do amostrador (fator de atrito a). Os resultados obtidos foram comparados com resultados de trabalhos experimentais e valores teóricos determinados com base no Princípio de Hamilton da conservação da energia. Também foi possível simular uma prova de carga dinâmica com energia crescente no amostrador, variando a altura de queda do martelo. Isso confirmou que a resistência mobilizada do solo para certa energia aplicada pode estar bem abaixo da ruptura e apenas representar um ponto na curva de resistência mobilizada versus deslocamento. / The Standard Penetration Test (SPT) is one of the most used geotechnical tests in the world. The wide use of this test in the context of geotechnical engineering is due to its simplicity, low cost, large practical experience and its ease of application of results. The main objectives of the test are the determination of soil resistance index (NSPT) and sampling. Despite being widely used in estimating the bearing capacity of foundations, the SPT test has been questioned by the fact that the NSPT index is used in empirical correlations based on practical observations, with no scientific basis. Furthermore, its results show significant dispersions. To analyze rationally the test results and to make possible to compare different results obtained from different equipment, it is necessary to know the amounts of energy existing during the penetration of the sampler into soil. Such analyses require information about the equipment efficiency (η) and the dynamic soil reaction force during the sampler penetration (RD). In this scenario, this work addresses the rational interpretation of SPT test results from numerical simulations performed with the Abaqus/Explicit software. This program provides the sampler displacements (Δρ), the dynamic soil reaction force (RD) and the external and internal reaction forces acting on the sampler walls (R1 e R2). Based on the results of the numerical models, it was possible to calculate the efficiency of the equipment, from the dynamic soil reaction force, the unit friction resistance acting on the sampler walls and the unit resistance at the sampler tip. In addition, it was possible to estimate the relationship between the unit friction resistance acting on the internal and external walls of the sampler (friction factor a). The numerical results were compared with experimental results and theoretical values, obtained using the Hamilton\'s principle of conservation of energy. Furthermore, it was possible to simulate a dynamic load test with increasing energy applied to the sampler, by varying the height of fall of the hammer. It was obtained the confirmation that resistance mobilized for a certain level of energy applied to the sampler may be below the failure load and represent only a point on the graph curve mobilized resistance versus displacement.

O estudo do comportamento de estruturas em situação de incêndio tem se tornado cada vez mais importante devido às graves consequências de incêndios que têm ocorrido no Brasil e em outros países. Por esse motivo, este trabalho tem como objetivo estudar o comportamento residual do concreto com pérolas de EPS sob altas temperaturas, pois se pretende utilizar esse concreto em painéis e em lajes pré-moldadas para a construção de edifícios de pequeno e de médio porte, por ele ser um concreto muito leve, com massa específica em torno de 1170 kg/m3, um pouco menos da metade da relativa ao concreto convencional. Para este estudo, foram utilizados corpos de prova cilíndricos e prismáticos, seguindo recomendações nacionais e internacionais. As análises foram realizadas para 200ºC, 400ºC e 600ºC, e foram avaliadas: massa específica, resistência à compressão, módulo de elasticidade estático, módulo de elasticidade dinâmico, resistência à tração por compressão diametral, resistência à tração na flexão e fator de tenacidade. Para esses dois últimos, foram utilizadas fibras de aço nas seguintes taxas: 0,3%, 0,6% e 0,9%. Os resultados foram comparados com os de concreto com EPS em temperatura ambiente e com os de concreto convencional, que já tem alguns resultados disponíveis na literatura técnica. Também foi realizada uma análise térmica numérica, utilizando o software ABAQUS 14, para calibrar duas propriedades: calor específico e condutividade térmica. Para isso, foram utilizados resultados obtidos na análise experimental. Os resultados numéricos e experimentais foram coerentes com os esperados. Os experimentais apresentaram redução de valor à medida que a temperatura aumentava, e comportamento pior em comparação ao concreto convencional. A adição de fibras aumentou a resistência à tração na flexão e também a tenacidade, tanto em temperatura ambiente quanto em temperaturas elevadas. / The study of the structures behavior in fire has become increasingly important due to the serious consequences of fires that have occurred in Brazil and in other countries. Therefore, this work aims to study the residual behavior of concrete with EPS beads under high temperatures, because it is intended to use it in panels and precast slabs for the construction of small and medium-sized buildings, for it is a very light concrete, with a density around 1170 kg/m3, slightly less than half that of conventional concrete. For this study, cylindrical and prismatic specimens were used, following national and international standards. The analyses were carried out to 200°C, 400°C and 600°C, and were evaluated: density, compression strength, static modulus of elasticity, dynamic modulus of elasticity, splitting tensile strength, flexural tensile strength, and toughness factor. For the latter two, steel fibers were used at the following rates: 0.3%, 0.6% and 0.9%. The results were compared with those of concrete with EPS at room temperature, and with conventional concrete which already has some results available in the technical literature. A numerical thermal analysis was also performed, using ABAQUS 14 software, to calibrate two properties: specific heat and thermal conductivity. For this, results obtained in the experimental analysis were used. The numerical and experimental results were consistent with those expected. The experimental results showed reduction of value as temperature increased, and worst behavior in comparison to ordinary concrete. The addition of fibers increased tensile strength in bending and also the toughness, both at room temperature and at elevated temperatures.