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This work is a stepping stone towards developing higher order shell element for simulating composite manufacturing procedure. In this study, a continuum approach suitable for combined material and geometrically nonlinear analysis for an eight node solid shell element SS8 is explained. The formulation of SS8 comprises two ingredients to alleviate undesirable locking effects: 1) Assumed Natural Strain concept, which has proven to alleviate the curvature thickness and transverse shear locking problems. 2) Enhanced Assumed Strain, which adds enhanced degrees of freedom to improve the in-plane response of the element and the curvature thickness locking problem. This formulation has been extended to represent geometric and material non-linearity using Total Lagrangian approach. Finally, finite strain formulation has been verified by numerical examples. Results when compared to continuum shell element in ABAQUS show a reasonable agreement with a relative error of less than 2%.

Quantifying hydraulic roughness coefficients is commonly required in order to calculate flow rate in open channel applications. An assumption typically coupled with the use of Manning’s equation is that a roughness coefficient (n) that is solely dependent upon a boundary roughness characteristic (k) may be applied. Even though Manning reported unique values of n and x’ (the exponent of the hydraulic radius in Manning’s equation) for each of the different boundary roughness materials he tested, he chose x’ = 2/3 as representative, assumed a constant n value, and suggested that it was sufficiently accurate. More recent studies have suggested that in addition to k; Rh, Se, and Fr can influence n. While research points to situations where n may vary, it is always a temptation to simply apply the constant n assumption especially in the case of more complicated channels such as composite channels where different roughness materials line different parts of a channel cross section. This study evaluates the behavior of n as a function of Re, Rh, k, So, and Fr for four different boundary roughness materials ranging from smooth to relatively rough in a rectangular tilting flume. The results indicate that for the relatively rough materials n is best described by its relationship with Rh where it varies over a lower range of Rh but approaches and at a point maintains a constant value as Rh increases. The constant value of n is attributed to both the physically smooth boundary materials and a quasi-smooth flow condition in the rougher boundary materials. The study shows that an x’ = 2/3 (the basis of Manning’s equation) correlated to the assumption of a constant n value only applies to smooth boundary roughness materials and a quasi-smooth flow condition in the rougher boundary materials; otherwise, either n or x’ must vary. These findings are then applied to compare 16 published composite channel relationships. The results identify the importance of applying a varying n where applicable due to the potential for error in assuming and applying a constant n. They also indicate that the more complicated predictive methods do not produce more accurate results than the simpler methods of which the most consistent is the Horton method.

Approved for public release; distribution is unlimited / The purpose of this thesis is to lay the foundation for analyzing structural coupling effects for a proposed trolley interface between a ship and a roll-on roll-off discharge facility (RRDF). Such a facility could allow heavy cargo transfer at higher sea states. Previous studies have analyzed motions assuming that there is no structural coupling between the trolley and the RRDF. A mathematical model that incorporates structural coupling is developed using the principle of virtual work. In order to assess the degree of necessity for the proposed model we conduct a systematic series of numerical experiments. In these calculations we model the trolley through a generalized stiffness coefficient and assess its influence on RRDF motions. It is shown that modeling of structural coupling may be necessary depending on the relative order of magnitude of trolley structural rigidity and trolley placement. / Major, Republic of Singapore Navy

A globalização e a forte competitividade obrigam as empresas a tornarem-se cada vez mais inovadoras e criativas. O diferencial conquistado através das inovações tende a agregar valor à empresa tornando-a mais forte para enfrentar a concorrência. Entretanto o pesado ônus tributário pode inviabilizar ou criar uma situação desfavorável para as empresas. Nesse contexto a contabilidade por meio de seu sistema de informação busca auxiliar os gestores no melhor planejamento de sua carga tributária. A gestão tributária significa procurar formas lícitas para reduzir, suspender ou adiar o pagamento de tributos, dentre elas está a melhor escolha na forma de tributação. O trabalho apresenta um estudo de caso em uma empresa prestadora de serviços onde será analisada a aplicabilidade da melhor forma de tributação da pessoa jurídica, no qual empresa poderá optar pelo lucro presumido, Lucro real anual ou trimestral, pois uma vez feita a opção, será irretratável para todo o ano calendário, o que pode gerar um ônus tributário que poderá reduzir significativamente a performance econômico-financeira. / Globalization and strong competition forces companies to become more innovative and creative. The balance achieved through innovations tends to add value to the company making them stronger to face the competition. However the tax burden may prevent or create an unfavorable situation for companies. In this context the accounts through its information system seeks help managers to better planning of its tax burden. The tax management means lawful ways to reduce, suspend or postpone the payment of taxes, among them is the best choice in the form of taxation. The paper presents a case study in a service company where the application will be considered the best form of taxation of legal entities, in which company may choose the presumed profit, quarterly or annual real income, because once the option will be irrevocable for the entire calendar year, which can generate a tax burden that can significantly reduce the economic and financial performance.

This study aims at the description, modelling and numerical prediction of ductile fracture in inelastic solids undergoing thermomechanical static or dynamic loading. Several research areas of contemporary interest in computer analysis of solids and structures are covered. The theoretical methodologies, computer implementations and practical applications will be treated. This thesis summarizes my recent research works since 1989 at the MSM Department of the University of Liège. However, it should also be useful to those who are interested in the most recent developments in finite element methods and in applying these techniques to the analysis of real industrial problems. Numerous references to original sources are included. For the convenience of the reader, each chapter of the thesis is designed to be self-contained, starts with a summary of the topic addressed, and finishes with an outline of the main results presented. Numerical examples are organized at the end of chapter 2 to 8 to assess the performance and applicability of the proposed mechanical and finite element models developed in each of them. Hereafter, a brief overview of the thesis is given. After a brief introduction in chapter 1, the numerical tools that are necessary to perform large strain thermomechanical static or dynamic analysis of solids are presented. In chapter 2, a general strategy for nonlinear dynamic finite element formulation is presented, including explicit and implicit time integration schemes. A special emphasis is placed on the application of high-speed metalforming and frictional contact-impact problems. Chapter 3 describes a strategy for solving problems involving transient thermal and thermomechanical analysis. A class of unified and mixed solid, thermal and coupled thermomechanical finite elements by assumed strain method is developed in chapter 4. Special care is taken to hourglass ans locking control. Once these developments are validated and their efficiency tested, it is then possible to tackle the problem of ductile fracture prediction and propagation. In chapter 5, a bibliographic research on the "local approach of ductile fracture" is presented. The implementation of six fracture criteria into various constitutive laws for predicting fracture initiation sites is also shown. A fully coupled elasto(-visco)-plastic damage model for isotropic material is developed in chapter 6. This model is based on irreversible thermodynamics theory and on the energy equivalence hypothesis. Chapter 7 presents the theoretical and experimental comparison for isotropic ductile material at fracture. Finally in chapter 8, the isotropic damage model of chapter 6 is extended to the case of anisotropic solids in which the damage growth itself is also anisotropic. The above developments have been implemented to an existing finite element code LAGAMINE developed since 1982 at the MSM Department of the University of Liège and are applied to many real engineering problems such as high speed rolling, magnetoforming, impact upsetting, dynamic forging, deep drawing of axisymmetric ans square cups, hot upsetting, warm folding of 3D sheet, non-isothermal hemispherical punch stretching, and other contact-impact examples.

A globalização e a forte competitividade obrigam as empresas a tornarem-se cada vez mais inovadoras e criativas. O diferencial conquistado através das inovações tende a agregar valor à empresa tornando-a mais forte para enfrentar a concorrência. Entretanto o pesado ônus tributário pode inviabilizar ou criar uma situação desfavorável para as empresas. Nesse contexto a contabilidade por meio de seu sistema de informação busca auxiliar os gestores no melhor planejamento de sua carga tributária. A gestão tributária significa procurar formas lícitas para reduzir, suspender ou adiar o pagamento de tributos, dentre elas está a melhor escolha na forma de tributação. O trabalho apresenta um estudo de caso em uma empresa prestadora de serviços onde será analisada a aplicabilidade da melhor forma de tributação da pessoa jurídica, no qual empresa poderá optar pelo lucro presumido, Lucro real anual ou trimestral, pois uma vez feita a opção, será irretratável para todo o ano calendário, o que pode gerar um ônus tributário que poderá reduzir significativamente a performance econômico-financeira. / Globalization and strong competition forces companies to become more innovative and creative. The balance achieved through innovations tends to add value to the company making them stronger to face the competition. However the tax burden may prevent or create an unfavorable situation for companies. In this context the accounts through its information system seeks help managers to better planning of its tax burden. The tax management means lawful ways to reduce, suspend or postpone the payment of taxes, among them is the best choice in the form of taxation. The paper presents a case study in a service company where the application will be considered the best form of taxation of legal entities, in which company may choose the presumed profit, quarterly or annual real income, because once the option will be irrevocable for the entire calendar year, which can generate a tax burden that can significantly reduce the economic and financial performance.

This work evaluates the capabilities of the RANS and LES techniques for the simulation of high speed reacting flows. These methods are used to gain further insight into the physics encountered and regimes present in supersonic combustion. The target application of this research is the scramjet engine, a propulsion system of great promise for efficient hypersonic flight. In order to conduct this work a new highly parallelised code, PULSAR, is developed. PULSAR is capable of simulating complex chemistry combustion in highly compressible flows, based on a second order upwind method to provide a monotonic solution in the presence of high gradient physics. Through the simulation of a non-reacting supersonic coaxial helium jet the RANS method is shown to be sensitive to constants involved in the modelling process. The LES technique is more computationally demanding but is shown to be much less sensitive to these model parameters. Nevertheless, LES results are shown to be sensitive to the nature of turbulence at the inflow; however this information can be experimentally obtained. The SCHOLAR test case is used to validate the reacting aspects of PULSAR. Comparing RANS results from laminar chemistry and assumed PDF combustion model simulations, the influence of turbulence-chemistry interactions in supersonic combustion is shown to be small. In the presence of reactions, the RANS results are sensitive to inflow turbulence, due to its influence on mixing. From complex chemistry simulations the combustion behaviour is evaluated to sit between the flamelet and distributed reaction regimes. LES results allow an evaluation of the physics involved, with a pair of coherent vortices identified as the dominant influence on mixing for the oblique wall fuel injection method. It is shown that inflow turbulence has a significant impact on the behaviour of these vortices and hence it is vital for turbulence intensities and length scales to be measured by experimentalists, in order for accurate simulations to be possible.

The micro-electromechanical systems (MEMS) industry has grown incredibly fast over the past few years, due to the irresistible character and properties of MEMS. MEMS devices have been widely used in various fields such as aerospace, microelectronics, and the automobile industry. Increasing prominence is given to the development and research of MEMS; this is largely driven by the market requirements. Multi-physics coupled fields are often present in MEMS. This makes the modelling and analysis o such devices difficult and sometimes costly. The coupling between electrostatic and mechanical fields in MEMS is one of the most common and fundamental phenomena in MEMS; it is this configuration that is studied in this thesis. The following issues are addressed: 1. Due to the complexity in the structural geometry, as well as the difficulty to analyze the behaviour in the presence of coupled fields, simple analytical solutions are normally not available for MEMS. The finite element method (FEM) is therefore used to model electrostaticmechanical coupled MEMS. In this thesis, this avenue is followed. 2. In order to capture the configuration of the system accurately, with relatively little computational effort, a geometric non-linear mixed assumed stress element is developed and used in the FE analyses. It is shown that the developed geometrically non-linear mixed assumed stress element can produce an accuracy level comparable to that of the Q8 element, while the number of the degrees of freedom is that of the Q4 element. 3. Selected algorithms for solving highly non-linear coupled systems are evaluated. It is concluded that the simple, accurate and quadratic convergent Newton-Raphson algorithm remains best. To reduce the single most frustrating disadvantage of the Newton method, namely the computational cost of constructing the gradients, analytical gradients are evaluated and implemented. It is shown the CPU time is significantly reduced when the analytical gradients are used. 4. Finally, a practical engineering MEMS problem is studied. The developed geometric nonlinear mixed element is used to model the structural part of a fixed-fixed beam that experiences large axial stress due to an applied electrostatic force. The Newton method with analytical gradients is used to solve this geometrically nonlinear coupled MEMS problem. / Dissertation (MEng (Mechanical))--University of Pretoria, 2007. / Mechanical and Aeronautical Engineering / unrestricted

This study presented the design and implementation of a spatial Hinf controller to suppress the free and forced vibrations of a cantilevered smart beam. The smart beam consists of a passive aluminum beam with surface bonded PZT (Lead-Zirconate-Titanate) patches. In this study, the PZT patches were used as the actuators and a laser displacement sensor was used as the sensor. In the first part of the study, the modeling of the smart beam by the assumed-modes method was conducted. The model correction technique was applied to include the effect of out-of-range modes on the dynamics of the system. Later, spatial system identification work was performed in order to clarify the spatial characteristics of the smart beam. In the second part of the study, a spatial Hinf controller was designed for suppressing the first two flexural vibrations of the smart beam. The efficiency of the controller was verified both by simulations and experimental implementation. As a final step, the comparison of the spatial and pointwise Hinf controllers was employed. A pointwise Hinf controller was designed and experimentally implemented. The efficiency of the both controllers was compared by simulations.