Structural fatigue life investigation of a rigidly mounted aluminium fuel tank

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dc.contributor.advisorVenter, Gerharden_ZA
dc.contributor.advisorTerblanche, E.en_ZA
dc.contributor.authorFranken, Christian Matthysen_ZA
dc.contributor.otherStellenbosch University. Faculty of Engineering. Dept. of Mechanical and Mechatronic Engineering.en_ZA
dc.date.accessioned2012-11-28T06:19:16Zen_ZA
dc.date.accessioned2012-12-12T08:19:34Z
dc.date.available2015-12-01T03:00:10Z
dc.date.issued2012-12en_ZA
dc.descriptionThesis (MScEng)--Stellenbosch University, 2012.en_ZA
dc.description.abstractENGLISH ABSTRACT: Structural cracks have formed in the sub-structure of a tank that is rigidly mounted onto a truck chassis. These cracks have all formed at welds joining the various components of the aluminium sub-structure. This thesis proposes a solution methodology to address these failures. The first phase of this methodology (failure investigation) relies heavily on determining the life of the structure with fatigue life calculations. These calculations are done using the stress life method supplemented by the hot spot stress method. Experimental tests were conducted at an operational air force base to compile a composite duty cycle that is representative of the typical operation of the vehicle. This is followed by a finite element analysis which is used to calculate the scaling factor required to determine the hot spot stresses in the structure. These hot spot stresses are determined for three different crack areas and the estimated fatigue life of each of these points are calculated. The estimated fatigue lives are compared to the actual lives that were reported by the maintenance personnel, to determine a correlation factor. The comparison yields a maximum correlation factor of 9.8 and a minimum of 3.9. It is suggested that the minimum correlation factor of 3.9 is used to assess future solutions. It is also suggested to reduce the stresses by at least 37% to achieve the desired service life. Recommendations regarding the design of a repair are given. The methodology presented in this thesis provides the groundwork for a typical solution methodology that can be used at GRW Engineering. Recommendations for improvements to the method and its components are given.en_ZA
dc.description.abstractAFRIKAANSE OPSOMMING: Strukturele krake het ontstaan in die substruktuur van ’n tenk wat rigied gemonteer is op ’n vragmotor onderstel. Die krake het almal ontstaan op sweislaste wat die verskillende komponente van die aluminium struktuur bind. Hierdie tesis stel ’n oplossingsmetodologie voor om hierdie falings aan te spreek. Die eerste fase van hierdie metodologie (falingsondersoek) maak hewig staat op berekeninge van strukturele vermoeidheid. Hierdie berekeninge word gedoen met behulp van die ‘stress-life’ metode aangevul deur die ‘hot spot stress’ metode. Eksperimentele toetse is uitgevoer op ’n operasionele lugmagbasis om ’n saamgestelde dienssiklus te bepaal wat verteenwoordigend is van die tipiese operationele omstandighede van die voertuig. Dit word gevolg deur ’n eindige element analise wat gebruik word om die skalering faktor te bereken wat nodig is om die ‘hot spot’ spanning in die struktuur te bepaal. Hierdie ‘hot spot’ spanning word bepaal vir drie verskillende kraak gebiede ten einde die beraamde vermoeidheidslewe van elk van hierdie punte te bereken. Die beraamde vermoeidheidslewe word vergelyk met die werklike lewe wat deur die instandhoudingspersoneel berig is, om ’n korrelasie faktor te bepaal. Die vergelyking lewer ’n maksimum korrelasie faktor van 9.8 en ’n minimum van 3.9. Daar word voorgestel dat die minimum korrelasie faktor van 3.9 gebruik word in die bepaling van toekomstige oplossings. Daar word ook voorgestel dat die spanning met ten minste 37% verlaag word om die verwagte lewensduur te bereik. Aanbevelings ten opsigte van ’n verbetering aan die huidige struktuur word ook gegee. Die metodologie wat in hierdie tesis aangebied word, bied die grondslag vir ’n tipiese oplossingsmetodologie wat by GRW Engineering gebruik kan word. Aanbevelings vir verbeterings aan die metode en die verskeie komponente word ook voorgestel.af_ZA
dc.embargo.terms2015-12-01
dc.format.extentxv, 99 pages ; illustrationsen_ZA
dc.identifier.urihttp://hdl.handle.net/10019.1/71971
dc.language.isoen_ZAen_ZA
dc.publisherStellenbosch : Stellenbosch Universityen_ZA
dc.rightsStellenbosch Universityen_ZA
dc.subjectFatigue life analysisen_ZA
dc.subjectHot spot stress methoden_ZA
dc.subjectAluminum -- Fatiqueen_ZA
dc.subjectFuel tanks -- Safety measuresen_ZA
dc.subjectFracture mechanicsen_ZA
dc.subjectCracking of aluminum tanksen_ZA
dc.subjectStress corrosionen_ZA
dc.subjectUCTD
dc.subject.otherMechanical & Mechatronic Engineeringen_ZA
dc.titleStructural fatigue life investigation of a rigidly mounted aluminium fuel tanken_ZA
dc.typeThesisen_ZA
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