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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
211

Konceptarbete om skidbalk i kompositutförande till BVS10 / Concept work of making a skid beam in composite material for a BVS10

Bohm, Markus January 2013 (has links)
This thesis has been performed at BAE Systems Hägglunds, which is located in Örnsköldsvik. Hägglunds has a wide background of engineering, where they have manufactured all from airplanes to lifting cranes. Currently they only produce track vehicles at Hägglunds, where they manufacture the CV90 and BVS10 models. This thesis concerns the BVS10 which is an all-terrain-vehicle. The main purpose with the BVS10 is to enable transportation of material and personnel thru tough terrain. It isn’t designed for hard combat because of its lack of armor in favour of mobilityThe background of this work is that the BVS10 in recent years has been used more and more in close combat. It has also driven over many IED’s in Afghanistan. Because of this a change in the design of the BVS10 had to be carried out, which led to more armor. This resulted in that the total weight increased from 10.5 tons to 15 tons. This caused unacceptable reduction in lifetime of the torsion springs and the vehicle had to be sent back for repair. BAE Systems then decided to put a lot of effort in decreasing the weight of the vehicle by using light weight material in some components.This work is about the development of a concept for the skidbeam where steel is replaced by a composite material. Due to lack of knowledge about fiber composite and their manufacturing processes, a pre-study was made. After the pre-study the concept work on the beam was initiated, but this was only the beginning. When the material in the beam was switched to composite it was required to redesign the components that’s attached to the beam in order to function correctly.Due to limitations in the geometry it was impossible to use glass fiber as the material. Glass fiber is much cheaper than carbon fiber but the strength and E-modulus is lower. Instead it was decided to use carbon fiber combined with epoxy, which is the most common use for structural applications. To minimize the weight of the beam it was decided to use adhesive bonding as much as possible.The concept work was carried out by a single person but it quickly became clear that cooperation with composite manufacturers was needed in order to come up with a good solution to the problem. A large number of Swedish companies were contacted. Nordic Aircraft was one of the most cooperative companies that also had good knowledge of prepreg materials. The prepreg manufacturing method was chosen for its high quality of the final products, and because they are relatively easy to handle.After much discussion and simulations, a final concept was developed whish Nordic Aircraft later on used to calculate a quotation. The concept was met with approval by BAE Systems. Nordic Aircraft claimed to have the knowledge and the experience to manufacture the beam. / Det här examensarbetet har utförts på BAE Systems Hägglunds beläget i Örnsköldsvik. Hägglunds har bred erfarenhet av ingenjörsarbete och de har tillverkat allt ifrån flygplan till lyftkranar. I nuläget produceras endast bandvagnsfordon hos Hägglunds, de tillverkar modellerna CV90 och BVS10. Detta arbete handlar om BVS10 som är ett allterrängsfordon. BVS10 huvudsyfte är att den ska kunna transportera materiel och personal genom svår terräng. Den är inte avsedd som attackfordon, då dess bepansring är lätt till förmån för mobilitet.Arbetets bakgrund är att den på senare år allt mer har använts i ”close combat” och därmed blivit mycket beskjuten. Den har även fått utstå IED:s (improvised explosive device) i Afghanistan. P.g.a. dessa faktorer krävdes det en förändring av fordonet och den blev allt mer bepansrad. Detta medförde att totalvikten ökade från 10.5ton till ca 15ton, vilket ledde till att fjäderbussningarna slets ut snabbare och behövdes bytas allt oftare. Därmed beslöt man att försöka sänka fordonets totala vikt med hjälp av att byta material i vissa komponenter.Det här arbetet handlar om att ta fram ett koncept till att byta ut stål mot kompositmaterial i skidbalken. Eftersom kunskapen om kompositer var begränsad gjordes en förstudie på detta, men också hur tillverkningsmetoderna för kompositer ser ut. Efter förstudien påbörjades konceptarbetet för balken men detta var endast början. Då materialet i balken byttes ut var komponenterna runt balken tvungna att designas om för att fungera.P.g.a. begränsningar i geometrin var det inte möjligt att använda glasfiber som material. Glasfiber är mycket billigare än kolfiber men har också lägre e-modul och styrka. Istället valdes kolfiber i kombination med epoxy, vilket är den mest använda kompositen för strukturella delar. För att begränsa viktökning på balken valdes limning så mycket som möjligt.Konceptlösningarna utfördes till en början individuellt, men man insåg snabbt att det krävdes samarbete med komposittillverkare för att komma fram till en bra lösning. Ett stort antal företag i Sverige kontaktades. Nordic Aircraft var ett av de mest samarbetsvilliga företagen som också hade bra kunskap om prepreg material. Prepreg som tillverkningsmetod valdes för dess höga kvalité på slutprodukterna och att de är relativt enkla att handskas med.Efter mycket diskussion och simuleringar var ett koncept framtaget för beräkningar av priset. Konceptet gillades hos BAE Systems och Nordic Aircraft ansåg sig ha kunskapen att tillverka detaljen. Nordic Aircraft gjorde en grov offert baserad på de krav som BAE Systems hade.
212

Finite element-based failure models for carbon/epoxy tape composites

Seon, Guillaume 13 April 2009 (has links)
Laminated carbon/epoxy composite structures are increasingly used in the aerospace industries. Low weight, elastic tailoring, and high durability make the composite materials well suited for replacement of conventional metallic structures. However the difficulty to capture structural failure phenomena is a significant barrier to more extensive use of laminated composites. Predictions are challenging because matrix (resin) dominated failure mechanisms such as delaminations and matrix cracking contribute to the structural failure in addition to fiber-dominated failures. A key to rigorous failure predictions for composites is availability of measurements to quantify structural model parameters including matrix-dominated stress-strain relations and failure criteria. Novel techniques for measurement of nonlinear interlaminar constitutive properties in tape composites have been recently developed at Georgia Institute of Technology. Development of methods for accurate predictions of failure in carbon/epoxy tape laminate configurations with complex lay-ups is the main focus of this work. Failures through delamination and matrix cracking are considered. The first objective of this effort is to implement nonlinear interlaminar shear stress-strain relations for IM7/8552 carbon/epoxy tape in ABAQUS finite element models and validate structural delamination failure predictions with tests. Test data for composite configurations with wavy fibers confirm that nonlinear interlaminar shear stress-strain response enables accurate failure prediction. The problem of the presence of porosity and its influence on failure was noted. The second objective is to assess the ability to simulate initiation and propagation of matrix-ply cracking. Failure models for IM7/8552 carbon/epoxy tape open-hole tensile coupons are built and validated.
213

Aplicação do Método dos Elementos Discretos formado por barras no estudo do colapso de estruturas

Kosteski, Luis Eduardo January 2012 (has links)
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.
214

Approche couplée expérimentation - modélisation multi-échelle pour la détermination du comportement mécanique des graves routières traitées aux liants : Application à la valorisation des Mâchefers d'Incinération de Déchêts Non Dangereux / Experiment-based modelling for determination of the mechanical behavior of non-hazardous waste incineration bottom ashes treated by binders : Application to Non-Hazardous Waste incineration bottom ash

Sow, Libasse 06 April 2018 (has links)
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.
215

Aplicação do Método dos Elementos Discretos formado por barras no estudo do colapso de estruturas

Kosteski, Luis Eduardo January 2012 (has links)
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.
216

Aplicação do Método dos Elementos Discretos formado por barras no estudo do colapso de estruturas

Kosteski, Luis Eduardo January 2012 (has links)
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.
217

A Measurement Tool for Consumption Pattern of Hand wiping Tissue Paper

Srinivas, Achanta January 2006 (has links)
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
218

Comparative assessment of implicit and explicit finite element solution schemes for static and dynamic civilian aircraft seat certification (CS25.561 and CS25.562)

Gulavani, Omkar Vitthal January 2013 (has links)
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.].
219

Parametrized Finite Element Simulation of Multi-Storey Timber Structures

Kuai, Le January 2017 (has links)
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.
220

Thermal Analysis of a Park Lock System in a DCT Transmission

Rudraraju, Venkata Sai Krishna Varma, Valishetty, Arjun January 2017 (has links)
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.

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