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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

Design Development of a Hydrostat : Construction of a hydrostat used in an underwater SAI-unit / Design av en hydrostat : Konstruktion av en hydrostat i användning till en SAT-enhet inom undervatten

Mohammadi, Abbas January 2021 (has links)
Working with and providing different military and industrial solutions, SBD’s (Saab Dynamic) work also involve underwater equipment and underwater weapon (UW) systems. Nowadays, there are a number of standards that should be followed to make weapon systems safe to use, transport and handle. SAI-units (Safety, Arming, and Ignition) are components with capacity to handle weapon systems such as UWs in a safe manner. An underwater SAI-unit contains a mechanical sensor part, called hydrostat, which acts as a pressure transmitter to initiate the function in the system. This component senses the hydrostatic pressure of water depending on the depth and transmits the data into other subsystems in the SAI-unit.The hydrostat used in a specific SAI-system has previously been utilizing conventional techniques in its construction, including a spring and a piston which acts in response to water pressure. SBD wanted to develop the hydrostat further to increase its performance and adaptability to today’s technology. Toachieve this, the systematic method of product development and safety requirements were considered. Because SBD’s work in this field involved military solutions, some values and data included in this report were obtained by arbitrary assumptions. The company would like the design solution for the current hydrostat to be minimized in cost, minimized in shape factor, but at the same time fulfill requirements regarding operating environment such as temperature and loading. A design solution was introduced, which was illustrated by a 3D-model in details. Strength analysis was done through the Computer Aided Engineering (CAE) software Abaqus. Underwater loading case was analyzed using the FEM, named UNDEX (Underwater Explosion).It was concluded that the temperature, load, and safety requirements were achieved. However, regarding the cost and the relative shape factor, the goals were not achieved when comparing the result data. The cost showed to be dependent mostly on material type, manufacturing method and number of pieces to be produced. / SBD:s arbete innefattar framställning av militära och industriella lösningar, men tillhandahåller ocksåolika utrustning och vapen inom undervatten. Numera finns det flertal standarder som bör följas för att göra vapensystemen säkra att använda, transportera och hantera. SAT-enheter (Säkring, Armering och Tändning) är komponenter som har egenskaper att hantera vapensystem såsom undervattensvapen på ett säkert sätt. Vissa SAT-enheter i undervattensvapen innehåller en mekanisk komponent, så kallad hydrostat, som fungerar som en tryckgivare för att initiera funktionen i ett undervattensvapensystem. Denna komponent som tryckgivare, känner av det hydrostatiska trycket som uppstår på grund av vattentyngden (beroende på djupet) och för vidare informationen till andra delsystem i en SAT-enhet. Hydrostaten som används i ett specifikt SAT-system nyttjar konventionell technologi i sin konstruktion,vilket huvudsakligen innehåller en spiralfjäder och en kolv som verkar i respons till vattentrycket. Detta projekt baserades på att SBD ville utveckla denna hydrostat ytterligare för att öka och anpassa dess prestanda med dagens teknik. För att detta skulle uppnås, beaktades den systematiska produktutvecklingsmetoden och säkerhetskriterier angivna i standarder. Eftersom SBD:s arbete innefattar militära lösningar, är de värden och data erhållna för denna rapport godtycklig antagna och inte riktiga. SBD ville att en designlösning för nuvarande hydrostat skulle minimeras i kostnad, vara minimerad i formfaktor, men samtidig uppfylla miljövillkor såsom temperatur och belastningar i vatten. En designlösning introducerades och illustrerades i detalj genom en 3D-modell. Hållfasthetsanalys gjordes i CAE-programmet Abaqus. I denna programvara analyserades belastning orsakad av undervattenexplosioner och dess påverkan på konstruktionen. Resultaten visade att temperaturkrav, belastningsfall och säkerhetskraven uppnåddes. När det gälldekostnad och relativa formfaktorn uppnåddes dock inte målen när erhållna resultatet jämfördes. Kostnaden visade sig bero mest på materialtyp, tillverkningsmetod och antalet artiklar som skulle produceras.
2

Verification of a Three-Dimensional Statics Model for Continuum Robotics and the Design and Construction of a Small Continuum Robot (SCR)

Gray, Ricky (Ricky Lee) 11 December 2009 (has links)
Continuum robots are biologically inspired robots that capture the extraordinary abilities of biological structures such as elephant trunks, octopus tentacles, and mamma-lian tongues. They are given the term continuum robots due to their ability to bend conti-nuously rather than at specific joints such as with traditional rigid link robots. They are used in applications such as search and rescue operations, nuclear reactor repairs, colo-noscopies, minimal invasive surgeries, and steerable needles. In this thesis, a model that predicts the shape of a continuum robot is presented and verified. A verification system to verify the validity and accuracy of the model is presented which allows easy and accu-rate measurement of a continuum robot tip position. The model was verified against a flexible rod, the core component of a continuum robot, resulting in an accuracy of 0.61%. Finally, this thesis introduces a novel robot design, consisting of a single rod for the backbone which can be manipulated by applying external forces and torques.
3

Simulation and Testing of Energy Efficient Hydromechanical Drivlines for Construction Equipment

Larsson, Viktor, Larsson, L. Viktor January 2014 (has links)
Increased oil prices and environmental issues have increased a need of loweringthe emissions from and the fuel consumption in heavy construction machines. Anatural solution to these issues is a lowered input power through downsizing ofthe engine. This implies a demand on higher transmission efficiency, in order tominimize the intrusion on vehicle performance. More specifically, alternatives tothe conventional torque converter found in heavier applications today, must beinvestigated. One important part of this is the task of controlling the transmissionwithout jeopardising the advantages associated with the torque converter, such asrobustness and controllability.In this thesis, an alternative transmission concept for a backhoe loader is investigated.The studied concept is referred to as a 2-mode Jarchow power-splittransmission, where a mechanical path is added to a hydrostatic transmission inorder to increase transmission efficiency. The concept is evaluated in computerbased simulations as well as in hardware-in-the-loop simulations, where a physicalhydrostatic transmission is exposed for the loads caused by the vehicle duringvarying conditions. The loads are in turn simulated according to developed modelsof the mechanical parts of the vehicle drive line.In total, the investigated concept can be used instead of the torque converterconcept, if the hydrostatic transmission is properly controlled. The results alsoshow that there is a high possibility that the combustion engine in the backhoeloader can be downsized from 64 kW to 55 kW, which would further increase thefuel savings and reduce the emissions.

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