No presente trabalho é apresentada uma versão do Método dos Elementos Discretos formado por barras (DEM) no estudo do colapso de estruturas. O Método dos Elementos Discretos foi introduzido, especialmente, para a simulação numérica de problemas de dano e fratura. Esse método tem habilidade natural para introduzir descontinuidades de uma maneira muito direta e intuitiva. Além disso, métodos discretos oferecem uma estrutura conveniente para dar conta da desordem da microestrutura do material por meio de modelos estatísticos. A versão do DEM utilizada neste trabalho consiste na discretização do contínuo em barras que formam uma treliça espacial regular, onde massas equivalentes são concentradas nos nós, e as rigidezes das barras são equivalentes ao contínuo que tentam representar. Leis uniaxiais de dano permitem modelar fratura e dano anisotrópico com relativa facilidade. Esta versão foi amplamente testada em diversos campos da Engenharia, entre eles, problemas dinâmicos, de impacto, geração e propagação de sismos, estudo de efeito de escala em rochas e concreto, análise da microestrutura de materiais. Este trabalho apresenta dois grandes temas, nos quais foram realizadas implementações no DEM que aumentam sua aplicabilidade. Também são implementadas modificações nas leis constitutivas antes utilizadas, e apresentadas, também, novas leis para dar flexibilidade na calibração dos modelos. São comparados os resultados utilizando as diversas leis na análise do efeito de escala de placas submetidas à tração. Também são analisados os resultados obtidos sob a óptica da teoria de escala multifractal. Neste campo, encontram-se respostas muito interessantes que explicam os mecanismos de fratura, assim como dão uma noção de que alterações deveriam ser realizadas no DEM para conseguir que o método fique completamente objetivo em relação à escala. Nesse processo, estudam-se diferentes formas de obter as dimensões fractais de placas de rocha submetidas à tração e é analisada a influência de alguns dos parâmetros do DEM, além da relação constitutiva utilizada. Finalmente, o DEM é introduzido dentro do sistema comercial Abaqus, com objetivo de resolver problemas com grande quantidade de graus de liberdade ou com as condições de contorno ou de carregamento muito complexos. Apresentam-se exemplos de validação e exemplos de aplicação que mostram as vantagens das inovações realizadas. / This paper presents a version of the Truss-like Discrete Element Method in the study of the collapse of structures. The discrete element method was introduced especially for numerical simulation of fracture and damage problems. This method has the natural ability to introduce discontinuities in a very direct and intuitive way. Moreover, discrete methods offer a convenient framework to account for the disorder of the material microstructure by means of statistical models. The truss-like Discrete Element Method (DEM) used in this work represents the continuum by means of a periodic spatial arrangement of bars with the masses lumped at their ends. The rigidity of the bars is equivalent to the continuum to trying to represent. Uniaxial damage Laws allow model fracture and anisotropic damage with relative ease. This version was widely tested in various engineering fields including: dynamics problems, impact, generation and propagation of earthquakes, study of scale effect in rock and concrete analysis of the microstructure of materials. This work presents two major issues in witch were performed DEM implementations that increase its applicability. To obtain a better description of the model modifications in the constitutive laws are implemented and new ones are presented. The scale effect results of plates of rock subjected to traction obtained to different laws are compared. These obtained results are examined under the Multifractal scaling law theory. In this field, very interesting answers that explain the mechanisms of fracture are found. They gives some notions of which changes should be made in DEM to obtain a fully scale objective method. In the process, different ways to obtain the fractal dimension of rock plates subjected to traction are studied. The influence of some DEM parameter and constitutive laws are also analyzed. Finally, the DEM has been implemented within the commercial system ABAQUS to solve problems with a large number of degrees of freedom or very complex contour or loading conditions. Presents examples of validation and application that show the benefits of innovations through.

Dans ce travail, il est question d'étudier la faisabilité d'une valorisation en techniques routières de granulats de Mâchefers d'Incinération des Dèchets Non Dangereux (MIDND). Cette étude se base en premier lieu sur une analyse expérimentale ayant permis d'obtenir leurs propriétés élastiques. Ces propriétés servent de données d'entrée à une modélisation multi-échelle hiérarchique développée pour étudier le comportement mécanique de graves base de MIDND traitées aux liants (ciment et bitume). La campagne expérimentale originale sur des particules de mâchefers a permis de les cartographier au Microscope Electronique à Balayage (MEB Pour ces particules, des modules d'élasticité moyens réduits variant de 15 à 68 GPa ont été trouvés par le biais de tests d'indentation en appliquant méthode de «Olivier and Pharr ». Les analyses chimiques ponctuelles qualitatives (EDS) effectuées ont permis d'obtenir la composition chimique des granulats de mâchefers. Partant d'une granulométrie de particules de MIDND 0/25 qui a fait l'objet d'une étude expérimentale [BEC 07], nous avons mis en place des modèles numériques 3D de grave routière traitée aux liants dans des Volumes Elémentaires Représentatifs (VER). Ces modèles sont basés sur une stratégie de modélisation dite « multi-échelles » hiérarchique. Deux types de liant sont étudiés : le ciment CEM 1 42,5 R et le bitume de [NGU 08). Pour les deux types de liant, les agrégats traités ont été décomposés en deux VER : sub-mesoscopique (0/6) et mesoscopique (6/25). Une application à valorisation des MIDND en techniques routières est faite dans les deux cas. Avec un traitement à 3% de ciment, une campagne de simulations numériques "Laboratoire virtuel" a été menée. A l'échelle sub-mesoscopique, des simulations multiaxiales menées sur le VER, ont conduit à l'obtention des paramètres permettant d'alimenter un modèle d'endommagement plastique utilisé à l'échelle mesoscopique pour différents degrés d'hydratation. A l'échelle mesoscopique, les caractéristiques mécaniques de la grave routière traitée au ciment, habituellement déterminées par le biais d'expérimentations, ont été retrouvées. La modélisation développée a ensuite été validée e comparant nos résultats numériques et quelques résultats expérimentaux de [BEC 07]. Avec un traitement à 5% de bitume, des tests de relaxation de contraintes ont été effectués aux deux échelles ct ont permis d'obtenir les propriétés thermo-rhéologiques de la grave de mâchefers traités au bitume : les modules de relaxation sont exprimés sous la forme de séries de Prony à une température de référence de 0 °C ; par ailleurs, les constantes de la loi Williams-Landel-Ferry (WLF) pour décrire le comportement thermo- rhéologiquement simple sont identifiées. Les séries de Prony sont obtenues par l'intermédiaire des modules élastiques normalisés. Les constantes de 1 WLF obtenues sont C 1 = 20 °C-1 ct C2 = 130 °C. La validation des paramètres identifiés a été faite en comparant les réponses du matériau hétérogène de grave-bitume et celles d'un matériau homogène à qui nous avons donné les propriétés identifiées tirées du matériau hétérogène. / In this work, the feasibility of a valorisation in road engineering of non-hazardous waste incineration bottom ash aggregates (NHWI) is investigated. This study is first based on an experimental determination of the elastic properties of the bottom ash particles. These properties serve as input data for hierarchical multi-scale modelling developed to study the mechanical behaviour of aggregates treated with binders (cement and bitumen). The original experimental campaign on the bottom ash particles allowed them to be mapped to the Scanning Electron Microscope (SEM). For the particles, a mean reduced modulus of elasticity in between 15 and 68 GPa was found by means of indentation tests and applying the "Olivier and Phan method. The chemical analysis of the aggregates was obtained using qualitative point chemical analyzes (OHS). Based on a 0/25 particle size distribution of NHWI, which was the subject of an experimental study [BEC 07] , we have implemented two 30 models < road materials treated with binders in Representative Elementary Volumes (REV). These models are based on a hierarchical multi-scale modelling strategy. Two types of binder are studied: cement CEM I 42.5 R and bitumen of [NGU 08]. For both types of binder, the treated aggregates we divided into two REV, at respectively the sub-mesoscale (0/6 mm) and the mesoscale (6/25 mm). An application to the valorisation of NHWI bottom ashes in road engineering is studied in both cases. With a 3% cement treatment, a numerical simulation campaign "Virtual Laboratory" was conducted. At the sub-mesoscale, the input parameters for the Concrete Damaged Plasticity Model used at the mesoscale are determined. At the mesoscale, the mechanical characteristics of the road materials usually determined through experiments have been found. The developed simulation strategy has been validated by comparing our numerical results and son experimental results of [BEC 07]. With a 5% bitumen treatment, stress relaxation tests carried out at the two scales enable one to obtain the thermo-rheological properties of the Bitumen Bound Gravel. These properties are the Prony series at a reference temperature of 0°C and the Williams-Landei- Ferry (WLF) law constants. Prony series are obtained by means of standardized elastic moduli. The obtained WLF law constants are Cl = 20 °C-1 and C2 = 130 °C. The numeric simulations have been validated by comparing the responses of heterogeneous and corresponding homogeneous materials.

No presente trabalho é apresentada uma versão do Método dos Elementos Discretos formado por barras (DEM) no estudo do colapso de estruturas. O Método dos Elementos Discretos foi introduzido, especialmente, para a simulação numérica de problemas de dano e fratura. Esse método tem habilidade natural para introduzir descontinuidades de uma maneira muito direta e intuitiva. Além disso, métodos discretos oferecem uma estrutura conveniente para dar conta da desordem da microestrutura do material por meio de modelos estatísticos. A versão do DEM utilizada neste trabalho consiste na discretização do contínuo em barras que formam uma treliça espacial regular, onde massas equivalentes são concentradas nos nós, e as rigidezes das barras são equivalentes ao contínuo que tentam representar. Leis uniaxiais de dano permitem modelar fratura e dano anisotrópico com relativa facilidade. Esta versão foi amplamente testada em diversos campos da Engenharia, entre eles, problemas dinâmicos, de impacto, geração e propagação de sismos, estudo de efeito de escala em rochas e concreto, análise da microestrutura de materiais. Este trabalho apresenta dois grandes temas, nos quais foram realizadas implementações no DEM que aumentam sua aplicabilidade. Também são implementadas modificações nas leis constitutivas antes utilizadas, e apresentadas, também, novas leis para dar flexibilidade na calibração dos modelos. São comparados os resultados utilizando as diversas leis na análise do efeito de escala de placas submetidas à tração. Também são analisados os resultados obtidos sob a óptica da teoria de escala multifractal. Neste campo, encontram-se respostas muito interessantes que explicam os mecanismos de fratura, assim como dão uma noção de que alterações deveriam ser realizadas no DEM para conseguir que o método fique completamente objetivo em relação à escala. Nesse processo, estudam-se diferentes formas de obter as dimensões fractais de placas de rocha submetidas à tração e é analisada a influência de alguns dos parâmetros do DEM, além da relação constitutiva utilizada. Finalmente, o DEM é introduzido dentro do sistema comercial Abaqus, com objetivo de resolver problemas com grande quantidade de graus de liberdade ou com as condições de contorno ou de carregamento muito complexos. Apresentam-se exemplos de validação e exemplos de aplicação que mostram as vantagens das inovações realizadas. / This paper presents a version of the Truss-like Discrete Element Method in the study of the collapse of structures. The discrete element method was introduced especially for numerical simulation of fracture and damage problems. This method has the natural ability to introduce discontinuities in a very direct and intuitive way. Moreover, discrete methods offer a convenient framework to account for the disorder of the material microstructure by means of statistical models. The truss-like Discrete Element Method (DEM) used in this work represents the continuum by means of a periodic spatial arrangement of bars with the masses lumped at their ends. The rigidity of the bars is equivalent to the continuum to trying to represent. Uniaxial damage Laws allow model fracture and anisotropic damage with relative ease. This version was widely tested in various engineering fields including: dynamics problems, impact, generation and propagation of earthquakes, study of scale effect in rock and concrete analysis of the microstructure of materials. This work presents two major issues in witch were performed DEM implementations that increase its applicability. To obtain a better description of the model modifications in the constitutive laws are implemented and new ones are presented. The scale effect results of plates of rock subjected to traction obtained to different laws are compared. These obtained results are examined under the Multifractal scaling law theory. In this field, very interesting answers that explain the mechanisms of fracture are found. They gives some notions of which changes should be made in DEM to obtain a fully scale objective method. In the process, different ways to obtain the fractal dimension of rock plates subjected to traction are studied. The influence of some DEM parameter and constitutive laws are also analyzed. Finally, the DEM has been implemented within the commercial system ABAQUS to solve problems with a large number of degrees of freedom or very complex contour or loading conditions. Presents examples of validation and application that show the benefits of innovations through.

No presente trabalho é apresentada uma versão do Método dos Elementos Discretos formado por barras (DEM) no estudo do colapso de estruturas. O Método dos Elementos Discretos foi introduzido, especialmente, para a simulação numérica de problemas de dano e fratura. Esse método tem habilidade natural para introduzir descontinuidades de uma maneira muito direta e intuitiva. Além disso, métodos discretos oferecem uma estrutura conveniente para dar conta da desordem da microestrutura do material por meio de modelos estatísticos. A versão do DEM utilizada neste trabalho consiste na discretização do contínuo em barras que formam uma treliça espacial regular, onde massas equivalentes são concentradas nos nós, e as rigidezes das barras são equivalentes ao contínuo que tentam representar. Leis uniaxiais de dano permitem modelar fratura e dano anisotrópico com relativa facilidade. Esta versão foi amplamente testada em diversos campos da Engenharia, entre eles, problemas dinâmicos, de impacto, geração e propagação de sismos, estudo de efeito de escala em rochas e concreto, análise da microestrutura de materiais. Este trabalho apresenta dois grandes temas, nos quais foram realizadas implementações no DEM que aumentam sua aplicabilidade. Também são implementadas modificações nas leis constitutivas antes utilizadas, e apresentadas, também, novas leis para dar flexibilidade na calibração dos modelos. São comparados os resultados utilizando as diversas leis na análise do efeito de escala de placas submetidas à tração. Também são analisados os resultados obtidos sob a óptica da teoria de escala multifractal. Neste campo, encontram-se respostas muito interessantes que explicam os mecanismos de fratura, assim como dão uma noção de que alterações deveriam ser realizadas no DEM para conseguir que o método fique completamente objetivo em relação à escala. Nesse processo, estudam-se diferentes formas de obter as dimensões fractais de placas de rocha submetidas à tração e é analisada a influência de alguns dos parâmetros do DEM, além da relação constitutiva utilizada. Finalmente, o DEM é introduzido dentro do sistema comercial Abaqus, com objetivo de resolver problemas com grande quantidade de graus de liberdade ou com as condições de contorno ou de carregamento muito complexos. Apresentam-se exemplos de validação e exemplos de aplicação que mostram as vantagens das inovações realizadas. / This paper presents a version of the Truss-like Discrete Element Method in the study of the collapse of structures. The discrete element method was introduced especially for numerical simulation of fracture and damage problems. This method has the natural ability to introduce discontinuities in a very direct and intuitive way. Moreover, discrete methods offer a convenient framework to account for the disorder of the material microstructure by means of statistical models. The truss-like Discrete Element Method (DEM) used in this work represents the continuum by means of a periodic spatial arrangement of bars with the masses lumped at their ends. The rigidity of the bars is equivalent to the continuum to trying to represent. Uniaxial damage Laws allow model fracture and anisotropic damage with relative ease. This version was widely tested in various engineering fields including: dynamics problems, impact, generation and propagation of earthquakes, study of scale effect in rock and concrete analysis of the microstructure of materials. This work presents two major issues in witch were performed DEM implementations that increase its applicability. To obtain a better description of the model modifications in the constitutive laws are implemented and new ones are presented. The scale effect results of plates of rock subjected to traction obtained to different laws are compared. These obtained results are examined under the Multifractal scaling law theory. In this field, very interesting answers that explain the mechanisms of fracture are found. They gives some notions of which changes should be made in DEM to obtain a fully scale objective method. In the process, different ways to obtain the fractal dimension of rock plates subjected to traction are studied. The influence of some DEM parameter and constitutive laws are also analyzed. Finally, the DEM has been implemented within the commercial system ABAQUS to solve problems with a large number of degrees of freedom or very complex contour or loading conditions. Presents examples of validation and application that show the benefits of innovations through.

Due to environmental concerns and competition within the industry there is an imminent need by paper manufacturers to asses the paper consumption depending on the quality of the tissue paper. For this purpose, the consumption of tissue paper from a tissue vending machine needs to be monitored and calculated. A Hall Effect Sensor coupled with a Passive Infrared Sensor was used to monitor the flow of paper per Person. MATLAB is used as the programming language to read the signals from the sensors. The consumption obtained would be used to obtain better, less bulky design models. As well deduce an optimum paper dimensions to get reduce the paper consumption. Also, the FEM was done in ABAQUS for better blade design of Hand wiping system. / achantasrinivas@gmail.com +46 704406894

Due to the competitive nature of airline industry and the desire to minimise aircraft weight, there is a continual drive to develop lightweight, reliable and more comfortable seating solutions, in particular, a new generation slim economy seat. The key design challenge is to maximise the “living space” for the passenger, with strict adherence to the ‘Crash Safety Regulations’. Cranfield University is addressing the needs of airliners, seat manufactures and safety regulating bodies by designing a completely novel seat structure coined as “Sleep Seat”. A generous angle of recline (40 degree), movement of “Seat Pan” along the gradient, fixed outer shell of the backrest, and a unique single “Forward Beam” design distinguishes “Sleep Seat” form current generation seats. It is an ultra-lightweight design weighing 8kg (typical seat weight is 11kg). It has to sustain the static (CS 25.561) and dynamic (CS25.562) “Emergency landing” loads as specified by “Certification Specifications (CS). Apart from maintaining structural integrity; a seat-structure must not deform, which would impede evacuation, should absorb energy so that the loads transferred to Occupants are within human tolerance limits and should always maintain survivable space around the Occupant. All these parameters, which increase a life-expectancy in a ‘survivable’ crash, can be estimated using either experimental testing or virtual simulation tools such as “Finite Element Analysis (FEA). Design of the “Sleep Seat” is still in its conceptual phase and therefore experimental testing for all the design iterations involved is unrealistic, given a measure of the costs and timescales involved. Therefore focus of research is to develop practical and robust FE methodologies to assess static and dynamic performances of a seat-structure so as to compare different design concepts based on their strength, seat interface loads (a limit defined by strength of aircraft-floor), maximum deformations and cross-sectional forces ... [cont.].

With the acceleration of global urbanization trends, more and more intentions are put on multi-storey buildings. As the world leading area of wood construction, European countries started the construction of multi-storey timber building for a decade ago. However, unlike the traditional buildings made of reinforced concrete, the design of wooden high-rise timber buildings would face a substantial amount of new challenges because such high-rise timber buildings are touching the limitations of the timber engineering field. In this thesis, a parameterized three-dimensional FE-model (in ABAQUS) of a multi-storey timber frame building is created. Variable geometrical parameters, connection stiffness as well as boundary connections and applied wind and gravity loads are defined in a Python script to make it possible to analyze the influence of these parameters on the global structural behavior of the studied multi-storey timber frame building. The results and analysis implied that the script successfully worked and was capable to create different complex building geometries in an wasy way for the finite element analysis.

A park lock is a mechanism used to prevent unintentional movement of the vehicle. A failure in the proper function of this mechanism can lead to the safety concerns of an automobile. The main focus of this thesis is to understand the reason behind the failure of the park lock mechanism by FEM analysis in ANSA. For this, temperature build up during the park lock engagement has been studied in a dynamic explicit analysis. The FE results are compared to results from experiments on park lock. The modelling has been done in ANSA, ABAQUS was used as a solver for simulation and the results have been studied in META. The results indicate that there is a rise in the temperature. This is due to the friction between the contact surfaces and the oscillations generated in the vehicle. Based on the observations, discussions and conclusions are formulated and the research questions are answered.

<div>Due to reduced pain, shortened hospital stay and recovery, minimally invasive surgery (MIS) is becoming more and more popular in healthcare systems. MIS requires some devices for the motion and force transformation from outside to the inside of the body of a patient, and the strangled cables play a significant role in developing the instrumentations to serve for such purposes. However, current design and selection of a strangled cable is mostly intuitive that depend greatly on designers’ experiences and availability of experimental data, which leads to non-optimized designs and longer design cycles. In this thesis, both of analytical modelling and numerical simulation are proposed to build the relation of applied torque and deflection of part, so that a strangled cable with a given configuration can be characterized in term of its load-deflection relation. The defined relation has its great significance and application potential in the design optimization and precise controls of medical devices for MISs.Besides the various patterns of strangled cables, a Helical hollow strand (HHS®) tube is a special type of strangled cables with single- or multiple- layer configurations., In each layer, each of the helical wires touches its two neighboring helical wires, and it has a coreless hollow at the center. Its primary application is to carry a torsional load in a twisting mode. As an extreme, there is a possibility that all helical wires touch each other, and this forms a statically indeterminate contact obstacle in design analysis. Numerical simulation would predict that contacts occur simultaneously at all possible contacting points under the circumference that the strand is fixed at one end against rotation. In addition, the friction at contacts will affect the torsional deformation; therefore, these contacts must be taken into consideration in the development of analytical and numerical simulation models.This thesis reports the results of the investigation on the characteristics of Helical hollow strand tube (HHS®), more specifically, the relation of torsional deflection and the applied torque over a tube in the clockwise (CW) direction. The numerical simulation approach to predict the torsional deflection of HHS with various design parameters and configurations is emphasized. </div><div><br></div>

A nonlinear finite element analysis was performed for an existing road bridge in order to see if that could show a higher load bearing capacity, as an alternative to repairing or replacing. The regular linear analysis had shown that the bridge could not take any traffic load due to the effects from large and uneven support settlements. It is a five-span reinforced concrete bridge with a continuous slab on supports made out of rows of columns. The width-to-span ratio was around 1 and the supports were angled up to about 30°, giving rise to a complex three-dimensional behaviour, which was seen and studied in the nonlinear results. Since the bending moment was the limiting factor, the nonlinear analysis focused on that. The direct result was that the load bearing capacity was 730 kN for the traffic vehicle boogie load, B, in the ultimate limit state. This was however only for the load case tested, and several more disadvantageous vehicle positions may exist. Other aspects also became limiting, as the maximum allowed vertical deflection in the serviceability limit state was reached at 457 kN. The most restraining though, was the shear capacity from the linear analysis; 78 kN, since it was not possible to simulate that type of failure with the shell elements used in the nonlinear finite element analysis. The main aim of the thesis was nonetheless reached, since the nonlinear analysis was able to show a significant increase in load bearing capacity.  A comparison was made with the settlements for the nonlinear case, to see how much influence they had on the load bearing capacity for traffic load. This was performed for both the bridge and a simple two-span beam. Both showed that there was no effect on the load bearing capacity in the ultimate limit. One thing to note was that the full settlements were applied, and with no relaxation due to creep.  Another aim of the thesis was to make comments on the practical usability of the nonlinear finite element method in load bearing capacity assessments. A linear analysis was performed before the nonlinear in order to be able to determine the load case to be used in the latter. This worked well, as the strengths of the two methods could then be utilized. Convergence problems were however encountered for the nonlinear when using the regular static solver. Due to this, the dynamic explicit calculation scheme was used instead, treating the case as quasi-static. This managed to produce enough usable results. It was concluded that the nonlinear finite element method is useable for assessment calculations, but that its strengths and weaknesses must be known in order to make it an efficient method.