The influence of steel grade on the fatigue life of bolted joints in the automotive industry

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dc.contributor.advisorVenter, Gerharden_ZA
dc.contributor.authorEllerbeck, William Vincenten_ZA
dc.contributor.otherStellenbosch University. Faculty of Engineering. Dept. of Mechanical and Mechatronic Engineering.en_ZA
dc.date.accessioned2023-03-02T08:31:41Z
dc.date.accessioned2023-05-18T07:08:56Z
dc.date.available2023-03-02T08:31:41Z
dc.date.available2023-05-18T07:08:56Z
dc.date.issued2023-03
dc.descriptionThesis (MCom)--Stellenbosch University, 2023.en_ZA
dc.description.abstractENGLISH SUMMARY: Within the automotive industry it is critical that fatigue failure is protected against, particularly in structural components. Fatigue approaches from design standards such as BS 7608 are commonly followed to avoid fatigue failure. The BS 7608 standard does not account for parent material strength, however, and consequently this study investigates the effect of parent material strength on the fatigue life of bolted joints. Commercial quality mild steel, S355 structural steel and Domex 550 high strength steel are used, with yield strengths of 291 MPa, 461 MPa and 598 MPa respectively. Single bolt simple lap joints are fabricated from each steel and tested until fatigue failure occurs at various load ranges. It is found that for bolted joints, fatigue performance improves with increased material strength. Higher strength steels exhibit greater variance in fatigue life, however, which must be accounted for in design. As a result the benefit of improved mean life is somewhat reduced. BS 7608 provides various joint detail classification types, however none perfectly match the lap joint used in this study. Consequently the results of these experiments are compared to BS 7608 using both net and gross cross sectional area stress. It is found that the design S-N curves best match the experimental data when the net cross section area stress is used. Using this approach, BS 7608 most accurately describes the fatigue life of joints made from S355 steel, is conservative for Domex 550 and over predicts the life of joints fabricated with commercial quality mild steel. The lap joint is also subjected to tensile tests, using digital image correlation to extract displacement data. This serves as a reference for comparing finite element models. Various finite element models of a bolted joint are developed and evaluated on complexity, computing requirements and accuracy.en_ZA
dc.description.abstractAFRIKAANSE OPSOMMING: Binne die motorbedryf is dit krities om, veral vir strukturele komponente, teen vermoeidheidsfaling te waak. Vermoeidheid ontwerpsbenaderinge soos die in BS 7608 word gereeld gebruik om vermoeidheidsfaling te vermy, alhoewel die BS 7608 kode nie materiaal sterkte in ag neem nie. As gevolg daarvan sal hierdie ondersoek die effek van materiaal sterkte op die vermoeidheidslewe van boutverbindings evalueer. Kommersiele kwaliteit sagtestaal, S355 strukturele staal en Domex 550 hoe sterkte staal word gebruik, met werksterktes van onderskeidelik 291 MPa, 461 MPa en 598 MPa. Enkel-bout oorslaglasse is uit elke staal vervaardig, en is tot vermoeidheidsfaling by verskillende belastingvlakke getoets. Die resultate wys dat vir boutverbindings, vermoeiheidslewe met hoer materiaal sterkte verbeter. Hoer sterkte staal vertoon egter groter variasie in vermoeiheidslewe, en dus moet ontwerpe dit in ag neem. Die voordeel van sterker staal word as gevolg hiervan verminder. BS 7608 maak gebruik van verskeie verbindings kategoriee, waarvan egter nie een perfek pas by die boutverbinding wat in hierdie studie gebruik is nie. Gevolglik word die resultate van hierdie eksperimente met BS 7608 deur die gebruik van beide die netto en bruto dwarssnit area spanning vergelyk. Daar word gevind dat die onwerspkode S-N kromme die beste by die eksperimentele data pas wanneer netto dwarssnit area spanning gebruik word. Met gebruik van hierdie benadering, voorspel BS 7608 die vermoeidheidslewe van boutverbindings uit S355 staal die beste, terwyl dit konserwatief die lewe van Domex 550 voorspel en die lewe van kommersiele kwaliteit sagtestaal oor-voorspel. Die boutverbinding is ook aan trektoetse onderwerp, met die gebruik van digitale beeldkorrelasie om verplasingsdata te onttrek. Dit dien as ’n verwysing vir die vergelyking van eindige-element modelle. Verskeie eindige-element modelle van die boutverbinding is op grond van kompleksiteit, rekenaarvereistes en akkuraatheid ontwikkel en geevalueer.af_ZA
dc.description.versionMasters
dc.format.extentix, 73 pages : illustrations, includes annexures
dc.identifier.urihttp://hdl.handle.net/10019.1/127190
dc.language.isoen_ZAen_ZA
dc.publisherStellenbosch : Stellenbosch University
dc.rights.holderStellenbosch University
dc.subject.lcshBolted joints -- Fatigueen_ZA
dc.subject.lcshMotor vehicles -- Materials -- Fatigueen_ZA
dc.subject.nameUCTD
dc.titleThe influence of steel grade on the fatigue life of bolted joints in the automotive industryen_ZA
dc.typeThesisen_ZA
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