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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.
1

Investigation of flat capacitor discharge electromagnetic launchers

Hoyle, Alastair Richard January 1999 (has links)
In this thesis, studies of flat or pancake type electromagnetic launcher systems are described. The studies involved the development of several numerical models, and are supported throughout by experimental investigation. The models were based on a coaxial filamentary division technique, and the results they provided were compared with those from a commercial electromagnetic finite element modelling package. They were used to investigate some of the many possible launcher structures and power supply arrangements, as part of a wide-ranging parametric study. The aim of this thesis was to gain an insight into the factors that affect the performance of the launchers. Several different techniques were implemented to reduce the computation time. Practical experimentation provided a clear demonstration of the launcher technology, and supplied valuable model validation data. To aid the experimental work new projectile speed and yaw measurement systems were developed, and these were supported by results from a high-speed camera. A novel dual projectile launcher was tested, and was shown to improve the launch efficiency and to operate at higher energies, due to the reduction in drive coil recoil. Projectile deformation was investigated in both solid discs and flat annular projectiles.
2

Finite-Element Analysis of Physical Phenomena of a Lab-Scale Electromagnetic Launcher

Chung, Bummo 10 July 2007 (has links)
As electromagnetic launcher (EML) is an apparatus that uses the electromagnetic (EMAG) force to propel an armature along a rail. An applied electric current, coupled with the resulting magnetic field, creates an EMAG force capable of accelerating an armature to velocities up to several thousand meters per second. The high sliding velocity, coupled with the electric current density, creates extreme thermal conditions at the interface between the rail and the armature that can cause melting at the interface. This project considers a lab-scale EML which is pre-loaded to establish the initial contact between arils and armature. This contact area influences the flow of the electric current and, therefore, it affects the thermal conditions significantly. This work presents a finite-element analysis (FEA) of the aforementioned physical phenomena of the lab-scale EML. This work is aimed at improving the understanding of the armature-to-rail performance and the useful life of an EML by developing a computer simulation which can be used as a design tool to acquire conditiodecoup for the best performance. A two-dimensional structural FEA is used to determine the structural deformation, the contact area, the contact pressure, the von Mises stress, and the material properties of the structural compliance. The vibration characteristics of the lab-scale EML armature are studied using Modal analysis. A three-dimensional electromagnetic FEA is performed to determine the EMAG force. Frictional and Joule heating are determined from a two-dimensional thermal FEA. The commercial finite-element package, ANSYS, is used in the simulation.
3

Study of Launcher Recovery Systems

Rojas Sigala, Mauro January 2020 (has links)
The space sector has been evolving due to the fast-technological advancements generating a reduction of manufacturing, cost and size in space missions, where highly capable performing small satellites are becoming the standard in this industry. Furthermore, the high launching cost limits the trend of cost reduction for the space missions, since the small satellites are sent as a second payload. An alternative to reduce this limitation is using reusable launchers which are key in the future of space industry, once they are optimized in efficiency and reliability. Therefore, an opportunity of design is presented, since the increase of small satellites missions requires a reduction of the cost in launch services a suitable option for the future market are the reusable launchers. The problematic of using recovery systems and reuse parts of the vehicle is the increase of weight due to the added systems that the vehicle needs to be recovered. This paper presents different engines and calculate the performance of each engine based on the needs of missions for small satellites. The starting conditions will be that the payload needs to be launched in low circular or elliptical orbits (altitudes of between 300 and 650 km) and the engine has the ability of vertical take-off, vertical landing. The design will also take into account the possibility of reusing parts of the vehicle and the reentry capability. Different combination of engines and fuels are setup in various configurations. For each case the mass analysis will be developed which will allow to calculate the performance for each engine. The important parameters are the number and type of engines, the ratios of the masses, the thrust-to-weight ratio and specific impulse. Once the mass analysis is obtained the following procedure is the selection of the design considering the empty mass. The best combination of characteristics of the engines will be the suitable candidate. Different assistance systems and techniques for the recovery are assessed to obtain a suitable option to improve the efficiency. The expected results are the calculation of the engine performance and how the selected design can be suitable for the space launcher sector for the small satellites. The expected results are a feasible vehicle for small satellites design based in the calculation of the engine parameters together with an efficient launch recovery system. The conclusion is that the space sector can benefit from the design, demonstrating that a launch vehicle with the reusable characteristics.
4

Mobile Sounding Rocket Launcher

Kvist, Gabriel January 2022 (has links)
The aim of this thesis is to look at the possibility for SSC, Swedish Space Corporation, to build a cost-effective mobile rocket launcher to be used for their most common sounding rockets. Having a mobile rocket launcher will give SSC the possibility to not only expand their own line of launchers but more importantly giving them the opportunity to launch rockets outside their own base. To ease transportation of the launcher it is required to fit in a 40ft container. This requirement is the major limitation during the design phase. To keep the cost down, emphasis will be put on trying to find solutions with commercial products. Concepts were developed during three phases and after presenting the concepts to involved personnel, feedback was given and the concept(s) were developed further. The third and final phase contain the chosen concept and suggestions are given regarding future work to be done before it can be manufactured.
5

Automatický stavěč kuželek – výtah a metač koule / Ninepin Bowling Automata – elevator and ball thrower

Robota, Jakub January 2021 (has links)
The goal of this master’s thesis was to design and construct ninepin ball elevator for automated pin setter machine and ninepin ball launcher to simulate load and to verify correct function of the setter machine. Also, a ball track was designed as a means of transport for the ball from elevator to launcher. Theoretical part of thesis contains research into ninepin bowling, its rules and analysis of different applicable solutions found on the market that deal with automated pin setters and their ball elevators. Furthermore, a separate research into ball launchers was conducted. Practical part of thesis was comprised of own solution to design and construction of elevator, which extended already designed pin setter machine. After this, track for ball was designed and constructed together with ball launcher which imitates load that would the machine experience during usual game.
6

Utformning av en Bollutslungare : Produktutvecklingsprojekt av en bollutslungare för hundsporten Flyball / Development of a ball launcher : Product development project of a ball launcher for the dog sport Flybal

Johansson, Jimmy January 2016 (has links)
This report is a product development project of a ball launcher as requested by Sörmons HundklubbLKk. The project har been carried out as a thesis for the Bachelor of Science for the Innovation anddesign engineer program at Karlstad University.The client wished to begin training in a dog sport called Flyball. This sport can be likened to a relayrace where two teams of dogs race against each other. One dog per team runs along a path, leapingover obstacles, up to a ball launcher. When the dog jumps at the ball launcher to stop its momentumand turn back, a ball, launched about two feet, is to be caught by the dog. The dog then returns thesame way along the track as it came to switch with the next dog on the team. The last dog who finishfirst wins for their team.Due to large costs when importing a ball launcher, and the product not being available in Sweden,the client wanted a Swedish version developed. The goal was to minimize the price with the criterionto maximize longevity.The work of the project has followed the product development process as studied at KarlstadUniversity, with great influence by idea generation techniques, analog and digital sketching, 3Dmodeling and mechanical drawing techniques. Construction of the prototype has been carried out inthe workshop at Karlstad University with an evolutionistic design approach. A combination of lateralthinking for creativity and vertical thinking for logic and confirmation was used throughout theproject.The result of the project was a prototype that could be tested in a real environment at the dog cluband was confirmed to function as desired. Due to the availability of material at the workshop,construction of the ball launcher was possible at no cost to the client. This was a request, althoughnot a requirement for the project.The client also wanted to keep the prototype which was constructed to use within the club fortraining purposes. Therefore the ball launcher was completed to a finished prototype after projectclosure. / Denna rapport behandlar ett produktutvecklingsprojekt av en bollutslungare på uppdrag av SörmonsHundklubb LKk. Projektet utfördes som ett examensarbete för högskoleingenjörsprogrammet iinnovationsteknik och design på Karlstads universitet.Uppdragsgivaren önskade börja med en hundsport som heter Flyball. Sporten kan liknas vid stafettdär två lag med hundar tävlar mot varandra. En hund per lag springer längst en bana över någrahinder fram till en bollutslungare. När hunden hoppar på bollutslungarens framsida för att vändakastas en boll ut en dryg halvmeter för att fångas av hunden. Hunden återvänder då längst banan föratt byta av med nästa hund i laget. Sista hund först i mål vinner för sitt lag.Då bollutslungaren var dyr att importera och inte fanns tillgänglig i Sverige önskade uppdragsgivarenatt en svensk version skulle utvecklas. Målsättningen var att minimera pris med kriteriet attmaximera livslängd.Arbetet följde produktutvecklingsprocessen såsom den studerats på Karlstads universitet med storinflytelse av idégenerering, analog och digital skissteknik, 3D-modellering och ritningsskapande.Konstruktion av funktionsmodell utfördes på verkstaden på Karlstads universitet med evolutionistiskutveckling av designen. En kombination av lateralt tänkade för kreativitet och vertikalt tänkade förlogik och bekräftelser användes genom projektet.Resultatet av projektet utmynnade i en funktionsmodell som kunde testas i verklig miljö påhundklubben och bekräfta att konceptet fungerade enligt önskemål. På grund av tillgängligt materialkunde konstruktionen av funktionsmodellen utföras utan kostnad för uppdragsgivaren vilket var ettönskemål, dock inte ett krav, för projektet.Uppdragsgivaren önskade behålla funktionsmodellen som skapades för att använda inom klubben förträning av Flyball. Därmed färdigställdes funktionsmodellen till funktionsredo efter projektets slutoch levererades till uppdragsgivaren.
7

Utgångshastighetsmätning av granater med dopplerradar för granatgeväret Carl Gustaf / Exit Velocity Measurement of Grenades with Doppler Radar for Grenade Launcher Carl Gustaf

Starck, Anton, Adell, Marcus January 2018 (has links)
Det här projektet genomfördes på Saab Dynamics AB, Karlskoga. Syftet med projektet var att utvärdera möjligheterna att använda en 24 GHz Dopplerradarsensor för automotive-industrin, vid mätning av utgångshastigheten för projektiler från granatgeväret Carl Gustaf. Mätning av utgångshastigheten är av intresse för att öka träffsäkerheten med projektilerna. Projektet är huvudsakligen teoretiskt, dvs inga skarpa tester utfördes. Slutsatserna som dras grundar sig på beräkningar för mätning med radar och de matematiska problem de för med sig. Resultatet visar att denna radartyp är kapabel att mäta granater som färdas i höga hastigheter. Eftersom radar mäter radiell hastighet och radarmodulen ej kan placeras i linje med projektilen, behöver den uppmätta hastigheten korrigeras. Det söktes efter en lösning att korrigera detta i realtid eller genom efterbehandling av inläst data. En sådan blev dock ej funnen. Av de utforskade alternativen var den realiserbara lösningen på detta problem att montera radarmodulen så att felet i uppmätt hastighet blir försumbart. / This project was carried out at Saab Dynamics AB, Karlskoga, Sweden. The purpose of the project was to evaluate the possibilities to use a 24 GHz Doppler sensor made for the automotive industry to measure the exit velocity of projectiles from the grenade launcher Carl Gustaf. Measuring the exit velocity is of interest to increase the accuracy of the projectiles. The project is mainly theoretical, i.e. no live testing was performed. The conclusions drawn are based on calculations for measurement with radar and the mathematical problems they create. The result shows that this radar type is capable of measuring grenades travelling at high velocities. Since radar measures radial velocity, and the radar module cannot be placed in line with the projectile, the measured speed needs to be corrected. It was attempted to create a solution to correct this in real time or through post processing of the submitted data. A solution to this problem was, however, not found. Of the options explored, the realizable solution was to mount the radar so that the error in measured speed becomes negligible.
8

Etude expérimentale multisensorielle de la dynamique des impacts d'oiseaux sur structures d'avions

Vandeveld, Thierry 16 September 2009 (has links)
Chaque année, d'innombrables collisions se produisent entre des avions en vol et des oiseaux. L'impact aviaire, menace redoutée par les pilotes, concerne tant l'aviation civile que son pendant militaire. Les statistiques démontrent que, même si fort heureusement le nombre d'accidents graves reste limité, les incidents sont de plus en plus nombreux. Parmi les acteurs qui luttent contre ce danger, les constructeurs d'avions jouent un rôle prépondérant. Contraints par des réglementations internationales, ils s'attachent à produire des éléments de structure qui résistent à l'impact d'oiseaux. Dans la mise au point de leur produits, les avionneurs démontrent cette résistance à l'aide d'essais d'impact : on accélère un simulant d'oiseau jusqu'à la vitesse voulue -- de l'ordre de la vitesse de croisière nominale de l'avion -- et on le projette sur un aileron ou un morceau de fuselage. La présente thèse doctorale, co-dirigée par les professeurs Philippe Bouillard de l'ULB et Marc Pirlot de l'ERM, contribue doublement à l'amélioration de ces techniques d'essais dynamiques. D'une part, elle réalise la mise au point et la validation d'un lanceur pyrotechnique à double étage pour l'accélération du simulant d'oiseau. Un canon de calibre 20 mm est combiné avec un accélérateur de calibre 160 mm. La combustion d'un mélange de poudre propulsive contenu dans une douille adaptée génère les gaz à haute température et à haute pression nécessaires à l'accélération d'un simulant d'oiseau dûment confiné dans un conteneur de protection. Un dispositif de séparation arrête le conteneur afin que seul le simulant d'oiseau percute l'élément d'avion à l'essai. La solution pyrotechnique à double étage mise au point est validée par de nombreux tirs instrumentés en vitesse, en accélération et en pression ; elle se révèle conforme aux exigences de sécurité et de reproductibilité. Le lanceur pyrotechnique présente par rapport aux solutions pneumatiques, utilisées à notre connaissance dans tous les autres centres d'essais, des avantages indéniables de compacité ainsi que de rapidité et de souplesse de mise en oeuvre. D'autre part, la migration des alliages métalliques vers les matériaux composites est amorcée depuis plusieurs années déjà dans le monde de la construction aéronautique. Pour optimiser les structures, une connaissance des caractéristiques de ces matériaux est indispensable. Les modes de rupture font partie des caractéristiques encore mal connues. La mesure du déplacement hors-plan lors du tir sur panneaux plans est une des manières de quantifier le comportement du matériau sous l'action d'un impact. Cette mesure s'opère généralement de manière statique, après le tir. Une méthode de mesure dynamique a été mise au point, basée sur l'emploi de techniques de stéréoscopie par corrélation numérique d'images. Cette technique a été validée au moyen d'une méthode métrologique indépendante d'extensométrie laser. ABSTRACT Countless collisions occur each year between airplanes and birds. Bird strike is a concern to both civilian and militay aircraft. Statistics show that, although the number of serious accidents fortunately remains low, the number of incidents keeps increasing. Amongst the actors tackling this issue, aircraft manufacturers play an important role. In compliance with international regulations, they have to produce structural elements that withstand bird impact. During the development of their products, aircraft manufacturers have to demonstrate this resistance through bird impact trials : a bird surrogate is accelerated to the required velocity - often close to the nominal cruise speed of the aircraft - and launched onto a flap or a piece of fuselage. This PhD thesis has been co-supervised by Professor Philippe Bouillard (ULB) and Professor Marc Pirlot (ERM-KMS). Its contribution to the improvement of the aforementioned dynamic trials is twofold. One one hand, a two-stage pyrotechnical launcher for bird surrogates has been developed and assessed. A 20 mm caliber gun is connected to a 160 mm diameter launcher. The combustion of a propellant mixture in a cartridge case generates high pressure, high temperature gases which accelerate a bird surrogate protected by a cylindrical container. A stripper refrains the container from hitting the target pane. The pyrotechnical solution has been assessed through an important number of firings where pressure, velocity and acceleration have been measured. The solution has proven compliance with both the safety requirements and the repeatability specifications. Its advantages compared to the pneumatic solutions used, as far as we know, in all other test centres, include compactedness as well as flexibility and high firing rate. On the other hand, migration towards composite materials has been initiated years ago in the area of aeronautical constructions. To optimize structures, a thorough knowledge of these new materials is required. Failure modes belong to the still badly known features of carbon reinforced plastics. Measuring the out-of-plane deformation when firing on a flat pane is one way of quantifying the material's behaviour under impact. This measurement is most frequently made in a static way, after completion of the firing. A dynamic measuring method has been developed, based upon stereoscopic digital image correlation techniques. This technique has been validated by means of an independent laser extensometer measuring method.
9

Millimeter Wave Microstrip Launchers And Antenna Arrays

Akgun, Erdem 01 December 2006 (has links) (PDF)
Coaxial-to-microstrip launcher and microstrip patch array antenna are designed to work at center frequency of 36.85 GHz with a bandwidth higher than 300 MHz. The antenna array design also includes the feeding network distributing the power to each antenna element. The design parameters are defined on this report and optimized by using an Electromagnetic Simulation software program. In order to verify the theoretical results, microstrip patch array antenna is produced as a prototype. Measurements of antenna parameters, electromagnetic field and circuit properties are interpreted to show compliance with theoretical results. The values of deviation between theoretical and experimental results are discussed as a conclusion.
10

Experimental Analysis And Modelling Of Wear In Rocket Rail Launchers

Acmaz, Emre 01 January 2012 (has links) (PDF)
Launchers are military systems that are responsible for communication with munitions, safe seperation and aiming of rockets and missiles to the target. Since they are military equipments, they are used in harsh environments. One of the most important design considerations for military equipment is its maintability and one of the most important parameter which affects the maintability is wear in launchers. Therefore, for predicting the life-time of a launcher, wear should be investigated beside other parameters such as fatigue etc. This thesis study includes experimental and modeling study about dry sliding wear in some mechanical parts of a typical rail launcher that is used in helicopters. Firstly, measurements about the material loss, which is generated during firing of missiles, were made on launcher components which have interfaces with missile. Then, these results were used to simulate the wear phenomenon by using a commercial finite element program, ANSYS. By the help of finite element model, crack initiation period depending on wear is tried to be evaluated without making additional firing tests.

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