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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.
31

Analysis Of High-g Camera Support Structure For Crash Test System

Erdogdu, Mahmut Gokhan 01 December 2009 (has links) (PDF)
Sled Crash Test System is one of the key elements in todays high safety vehicle designs. In the crash test systems, high speed imaging by high speed cameras is required. For the success of high speed imaging, high speed cameras should be well secured on the sled of the system which is being accelerated to high-g values to simulate vehicle crash. In this study, structural analysis of the high &ndash / g camera support structure for the sled crash test sytem which is available in METU-BiLTiR Center Vehicle Safety Unit is carried out. For the secure connection of the high speed cameras, three different configurations of the camera support structure with different camera positions are analyzed by transient dynamic analysis. The finite element simulations are carried out under the acceleration of 90 g which is the maximum applicable acceleration on the system. After verification of the configurations with the computer simulations, one of the configuration has been tested at the sled test facility of METU-BILTIR Center Vehicle Safety Unit.
32

Estudo de impacto usando elementos finitos e análise não linear. / Impact study using finite element and non-linear analysis.

Cesar Antonio Aparicio Sánchez 02 April 2001 (has links)
Quando ocorre uma colisão, o comportamento estrutural de veículos, componentes ou sistemas mecânicos é analisado através de um parâmetro chamado crashworthiness, conceituado como a capacidade ou habilidade de uma estrutura, ou parte dela, de absorver energia cinética (resultante de impacto) e manter o colapso sob controle, mantendo a integridade no espaço do(s) ocupante(s). Este parâmetro pode também ser determinado para outro tipo de estruturas, como por exemplo, dispositivos de armazenamento de material (containers). Esta dissertação apresenta uma revisão bibliográfica sobre crashworthiness e o comportamento de estruturas quando submetidas a ensaios de impacto. Apresentam-se conceitos, histórico, evolução e principais áreas envolvidas. Destaca-se a utilização de programas de modelamento por elementos finitos na simulação e análise de colisão. Simula-se e analisa-se o impacto de modelos simplificados de container, típicos para o armazenamento de material radioativo, em queda livre contra uma superfície rígida, utilizando o software de elementos finitos ANSYS/LS-DYNA numa análise dinâmica explícita, apresentando-se resultados e conclusões e sugestões para trabalhos futuros. / The structural behavior of a vehicle or a mechanical system during collision is a very complex event. To analyze this behavior it's necessary to submit them to crash tests. These tests are made for the determination of the structure behavior and measure the kinetic energy absorption capability of a structure produced during a collision. This parameter is known as crashworthiness. In this work it is made a bibliographical review about crashworthiness and the behavior of structures under impact tests. Also, concepts, historical, evolution and the main involved areas are presented. The use of software's of finite elements in modeling and analyze of impact tests its highlighted. The drop test of a model of container, typical to storage of radioactive waste, is performed using the software of finite element ANSYS/LS-DYNA in an explicit analysis. Results, conclusions and comments for futures works are presented.
33

Avaliação do desempenho estrutural de barreiras de segurança de concreto armado para uso em rodovias / Structural performance evaluation of reinforced concrete safety barriers for use on highways

Paulo Cesar de Oliveira Queiroz 13 May 2016 (has links)
As barreiras de concreto são dispositivos utilizados como componentes de segurança em rodovias, que visam absorver o choque lateral de veículos desgovernados, propiciando sua recondução à faixa de tráfego e minimizando os danos aos ocupantes do veículo. Neste trabalho é analisado o desempenho de barreiras de concreto com o uso de modelos experimentais e numéricos baseados nas recomendações das normas brasileiras e internacionais. O estudo consiste em analisar a eficiência estática e dinâmica dessas barreiras. A análise estática engloba o estudo de distribuição de tensões na barreira considerando diferentes tipos de conectores, modo de ruptura, bem como a resistência desses conectores através de ensaios experimentais. Os ensaios são realizados de acordo com os critérios estabelecidos pela norma americana AASHTO LRFD 2012. A análise numérica, realizada com o uso de software de elementos finitos LS-DYNA©, contempla a atuação da geometria e da rigidez da barreira no processo de absorção de energia de impacto entre a barreira e o veículo, a eficiência do seu redirecionamento e adequação para os níveis de contenção estabelecidos em normas internacionais. Os resultados evidenciaram que a geometria da barreira é um fator importante para o desempenho da mesma, e, também que o uso de conectores em barreiras temporárias são primordiais para o bom funcionamento do sistema de contenção. / Concrete barriers are devices used as safety components in roads, which aim at absorbing side impact of unguided vehicles, redirecting them to the traffic lane and minimizing damage to the vehicle occupants. The present work analyzes the performance of concrete barriers through experimental and numerical models based on the recommendations of the Brazilian and international standards. The study consists in analyzing the static and dynamic efficiency of these barriers. The static analysis includes determining the stress distribution and yield lines in the barrier for different types of connectors, as well as studying the resistance of these connectors by performing experimental tests; these tests were conducted according to the criteria established by the American Standard AASHTO LRFD 2012. The numerical analysis, conducted with the commercial finite element software LS-DYNA©, evaluates the effect of geometry and stiffness of the barrier on the energy absorption performance., efficiency in redirecting the vehicles and suitability for providing restraint levels established in international standards. The results showed that the geometry of the barrier is an important factor for the barrier performance. In addition, the use of connectors in temporary barriers is essential for the smooth operation of the containment system.
34

Poškození vozidel při nárazech v malých rychlostech / Impact Damage to Vehicles at Low Speed

Holyszewská, Anna January 2017 (has links)
The thesis deals with documentation of the most common types of damage of vehicles at low speed, so-called ‘parking manoeuvers’. An analysis of characteristic damage was based on tests published so far, the author’s own tests and an analysis of real insured events. The results of the author’s own tests are compared to the procedures of the insurance company in the cases of potential insurance claims. The output of this thesis is a comprehensive presentation of the results of the impact tests carried out by the author which serve for the use in the assessment of insured events.
35

Analýza naměřených dat z nárazových zkoušek - čelní střety / Crash-Test Data Analysis - Frontal Impacts

Mikulášková, Lucie January 2017 (has links)
In this thesis are solved the problematics of crash tests. It is focused primarily on front impacts with full or part overlap. In the introduction are described the best known methods used in forensic - engineering practice for determination of energy equivalent speed (EES). Exactly specified impact tests, which are part of passive safety, are being addressed by several organizations around the world. In the practical part of this diploma thesis are solved four frontal impact tests, which were documented with the participation of the Institute of Forensic Ingeneering BUT in Brno.. These impact tests were performed to capture and analyze the data, resulting in the deformation energy used for permanent damage to the vehicle. Subsequently, the EES parameters were set for each vehicle.
36

Studie vlivu parametrů modelu na simulaci pojišťovacího nárazu vozidla / Study of Model Parameters Influence on Vehicle Insurance Impact

Šandera, Petr January 2009 (has links)
The diploma thesis deals with basic test procedures conducted by companies Euro NCAP and RCAR. It focuses mainly on insurance impact and describes the creation of a model, simulation and crash on barrier. Moreover, it explores the influence of change of yield strength, thickness and hardening of material of energy-absorber on simulation of insurance impact, especially the amount of absorbed energy by energy-absorber.
37

Analýza a zpracování naměřených dat z nárazových zkoušek / Analysis and processing of measured data from crash tests

Klein, Martin January 2016 (has links)
This thesis presents four crash test of two cars, in which always a moving vehicle strikes with fully overlaid front part into the side part (cabin for passengers) of another stationary vehicle. Crash test were carried out to detect the impact parameters for use in the road accidents analysis. Experimentally measured data and the acquisition of documentation during crash tests were therefore analyzed in an appropriate manner in order to obtain relevant impact parameters. One of the main evaluated parameters was the deformation energy that has been used for the permanent damage to vehicles. In the forensic engineering practice for analyzing vehicle impacts is as a control parameter used EES (Energy Equivalent Speed), this parameter was counted according to measured values during crash tests.
38

Analyse du comportement mécanique des côtes humaines en dynamique

Charpail, Estelle 27 October 2006 (has links) (PDF)
Dans les accidents automobiles, les blessures au thorax arrivent en deuxième position après celles à la tête pour : la zone la plus souvent lésée et le nombre global de décès et de lésions sérieuses. Les fractures de côtes et les volets costaux sont les blessures les plus fréquentes suivies par les lacérations des poumons, du foie et des artères. Afin de mieux comprendre la réponse du thorax lors d'un crash, des modèles en éléments finis ont été développés. Cependant, ces modèles échouent à reproduire des mécanismes lésionnels détaillés tels que les fractures costales. Améliorer la biofidélité de ces modèles passe par une meilleure connaissance des propriétés mécaniques des côtes. L'objectif de ce travail est donc d'étudier expérimentalement et numériquement le comportement mécanique des côtes humaines en dynamique. Des essais de compression axiale et des tests de calcination ont été réalisés pour caractériser le matériau costal. Des essais de flexion trois points et un nouvel essai permettant de solliciter la côte dans la direction antéropostérieure ont servi à caractériser la structure. Les résultats montrent que le niveau costal influence les propriétés de matériaux en compression et le comportement en sollicitation antéropostérieure. Les simulations numériques ont permis de mettre en évidence l'influence de l'os spongieux dans le comportement mécanique des modèles ainsi que l'importance de la géométrie sur la réponse en effort. Aucune influence de l'âge, ni de la vitesse de sollicitation a été relevée. Il faut noter le nombre de pièces testées est petit par rapport aux variations inter-individuelles.
39

Évaluation et modélisation des dispositifs de retenue pour motards / Design and Assessment of Motorcyclists Restraint Systems

Kodjo, Vidjannagni 02 September 2016 (has links)
En France, en 2015 les motocyclistes représentent 43% des blessés graves victimes d'accidents de la circulation routière. Au même moment, même si les accidents de chocs de motocyclistes contre les dispositifs de retenue routiers ne représentent en moyenne que 10% des accidents de la circulation routière, les motocyclistes présentent un risque de décès 30 à 80 fois supérieur au risque de décès des usagers de véhicules impliqués dans le même type d'accidents.Pour renforcer la sécurité des motocyclistes, les dispositifs de retenue pour automobiles (dispositifs traditionnels) sont équipés à leur partie inférieure d'écran de protection motards. Les écrans motards ont pour but d'amortir de manière progressive les chocs des motocyclistes en les empêchant dans le même temps de passer à travers la partie inférieure des dispositifs de retenue pour automobiles, de percuter un poteau et d'être sévèrement blessés. Les écrans motards doivent subir des essais de chocs normatifs et répondre à certaines exigences afin de pouvoir être installés sur le bord des routes européennes et de garantir surtout la sécurité des motards. Cependant, il n'existe que des procédures normatives pour tester ces dispositifs, la procédure LIER dans le contexte Français et la procédure normative EN 1317-8 dans le contexte Européen. Afin d'évaluer ces deux procédures normatives et de proposer de nouvelles dispositions pouvant servir de procédure normative plus avancée sur le protocole d'essais d'évaluation de performances d'écrans motards, des simulations numériques ont été réalisées. Un modèle numérique complet de dispositif de retenue routier équipé d'écran motard en acier a été développé et corrélé sur un essai de choc réel sur un dispositif de même type. Une fois corrélé,le modèle a été utilisé afin d'évaluer l'influence des conditions d'essais et des caractéristiques mécaniques matériaux de l'écran sur les performances de l'écran motard. Enfin, une nouvelle démarche d'évaluation de performances d'écran de protection motard a été mise en place / In France, in 2015,motorcyclists represent 43% of seriously injured accident victims in road traffic. At the same time, even though motorcyclists impact crashes against the road restraint systems represent on average 10% of accidents in road traffic, motorcyclists present a risk of death from30 to 80 times upper than the risk of death for users of vehicles involved in the same type of accidents. To enhance the safety of motorcyclists, Vehicle Restraints Systems (VRS) arefitted to the lower part of restraint systems for motorcyclists. Motorcyclist’s Restraint Systems (MRS) are designed to absorb shocks gradually and to preventmotorcyclists to pass through the lower part of VRS, to hit a post and be severely injured. Before being installed on the roadsides, MRS have to be crash-tested according to standards in order to evaluate their safety and ensure motorcyclists safety. However, there are only normative procedures to testMRS, the LIER procedurein the French context and the procedure EN1317-8 in the European context. To assess both normative procedures and propose new provisions which can be used as normative procedure more advanced on the protocol of MRS performances evaluation tests, numerical simulations were performed. A numerical model of MRS was developed and correlated on one real impact test on other device of same type. Once correlated, the model was used to conduct a parametric study on the test conditions and thematerialsmechanical properties of the MRS. Finally, a new demarche of MRS performances evaluation was developed
40

Návrh konstrukčních úprav pro zmírnění následků předního nárazu automobilu do nedeformovatelné bariéry / Design of the structural modifications for mitigating the consequences of the car frontal crash into the rigid barrier

Hošek, Štěpán January 2019 (has links)
There are many collisions on the roads every day. Automotive companies do number of different types of crash-tests to reduce the consequences of these collisions. Crash-tests are supposed to uncover problems of tested vehicles. Then it is possible to propose constructional changes to reduce the consequences of different types of collisions. Indipendent organisations then test productional vehicles according to their standarts and evaluate safety of these vehicles. One of these crash-tests is the small overlap test which is being done by Insurance Institute for Highway Safety. The small overlap test will be the subject of this thesis. Computational modelling of small overlap test is realised for basic variant and for variants with changes. There is also comparison of basic variant and variants with changes.

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