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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

Utveckling och dimensionering av en lastupptagande provningsram

Rosén, Jonatan January 2013 (has links)
ÅF Test Center in Borlänge had a need to expand their capacity for compressive and tensile strength tests. They wanted to do this by using a hydraulic cylinder, which they already possessed, to apply the force with. This required a load receiving structure. The aim of this work was to design and dimensioning a test bench for a cylinder marked NIKE 300 tons. The work would result in a completed design proposal on a test bench which could manage to run the compressive and tensile strength tests of up to 3000 kN. Compression and tensile tests are important tests to ascertain the material properties, which are important in the design and dimension work. The tests can simulate real load situations and then evaluated and verified products strength.   The project has involved searching and collecting data of the current hydraulic cylinder to produce a specification. A literature study has been carried out on strength tests were also existing products are studied. A number of concepts have been developed and evaluated against the requirements and ability to meet the strength requirements. Calculations have been performed of the test bench so it can be designed against the established strength requirements. The work also included an investigation how applied force should be measured.   The designs are developed with consideration of simplicity, minimum of components and manufacturing facility. The dimension has formed out from facts that static compressive and tensile tests will be carried out on the bench. The applied force is measured by a pressure sensor mounted on the hydraulics to the cylinder. It was a low cost alternative as they are not expensive in comparison with load cells or other discussed methods.   The test bench who are presented is a completed design proposal that meet the goal of project and the terms of specifications. The work presents in order to CAD models of the design, drawings have been produced and there is documentation of calculations for the dimensioning. It is recommended that a FEM analysis is done to ensure the strength of the test bench. Further preparation of drawing documentation is required before the test bench is ready for manufacturing.
2

Proving Ground Durability Simulations / Simulering av utmattning på provbana

Ramakrishnan, Siddharth January 2019 (has links)
Virtual durability simulations have been explored in the automotive industry to complement physical testing in designing durable vehicles. Simulations are useful to check the validity of the design before even building the prototype of the vehicle. They are also useful in checking the effect of changes in vehicle design to the durability of the vehicle. Buses are designed and tested for durability before they are sold to customers. Bus manufacturers use special test tracks consisting of different kinds of maneuvers/obstacles to test the buses for durability. Proving ground durability test schedules defines the combination of different test track maneuvers/obstacles at which the bus is to be run. The test schedules are created to achieve accelerated fatigue damage in the bus comparable with the fatigue damage occurring in typical customer usage. This thesis is an attempt to check if a proving ground durability test schedule can be simulated in a computer. A Multibody dynamic model of the bus with its constituent subsystems is modeled in a multibody simulation software MSC ADAMS. Sub-systems like bus chassis frame and axle are modeled as flexible as their dynamic properties are assumed to influence the simulation results. The virtual bus is run on the virtual version of the test tracks. Loads at suspension torque rods, anti-roll bars, axles and displacement of dampers are extracted from the simulation. The load signals are post-processed to derive fatigue damage. The simulation model is compared with the test results of a single standard test track maneuver. The simulation model is tuned by adjusting the parameters to match with the test results of the given maneuver. Finally, the tuned model is used to run the bus in a test schedule. Results achieved at the end of the thesis shows that well-tuned simulation model is necessary for simulating test schedules with enough accuracy. Comparison with test results are to be treated with caution as the conditions of the test bus should be exactly same as the simulation model; which is difficult to achieve. Future extension of the work involves improving the accuracy of simulations and using simulations to iterate new kinds of maneuvers/obstacles to improve existing test schedules. / Virtuell hållfasthetsprovning utnyttjats inom fordonsindustrin för att komplettera fysisk provning med avseende att konstruera hållfasta fordon. Simuleringar är användbara för att kontrollera designen innan första prototypen har byggts men även för att kontrollera hur hållfastheten påverkas av olika fordonskoncept. Bussar utvecklas och provas så att de ska klara målen för hållfasthet innan de säljs. Busstillverkarna använder speciella provbanor bestående av olika hinder och manövrar för att testa hållfastheten. Tillsammans med speciella provningsprogram som specificerar vilka provbanehinder och manövrar som bussen ska provas enligt kan hållfastheten säkerställas. Dessa provprogram är framtagna för att den accelererade utmattningen på provbanan ska matcha den utmattning bussen utsätt för hos kund. Denna avhandling undersöker huruvida provprogram kan utvecklas digitalt via simuleringar. Multidynamiska modeller av bussens delsystem modelleras i programvaran MSC ADAMS. Delsystem som buss chassi ram och axlar modelleras som flexibla då deras dynamik egenskaper anses påverka simuleringsresultaten. Den virtuella bussen provas på en digital provbanan. Krafterna i reaktionsstag, kränghämmare, axlar och förskjutningen i stötdämpare beräknas. Dessa kraft- och förskjutningssignalser används senare för att beräkna utmattning. Simulerade resultat av ett hinder jämförs med resultat från fysisk provning för att därefter justera vissa parametrar för att virtuella resultat ska matcha fysiska. Efter att modellen är optimerad kan slutligen delskadan för ett helt provprogram simuleras. Resultat visar på att en väll optimerad simuleringsmodell är nödvändig för att simulera fram provprogram med bra noggrannhet. Att jämföra simulerade resultat med fysiska ska göras med viss aktsamhet då den fysiska bussen bör vara identisk med den virtuella; vilket är mycket svårt att uppnå. Framtida arbete inom ämnet bör innefatta förbättringar av simuleringsnoggrannheten och använda simulering för framtagandet av nya hinder/manövrar för att förbättra befintliga provprogram.

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