| Summary: | Thesis (MEng.)-- University of Stellenbosch, 1992.
140 leaves on single pages, preliminary pages i-xi and numbered pages 1-113. Includes bibliography. Digitized at 600 dpi grayscale to pdf format (OCR),using an Bizhub 250 Konica Minolta Scanner and at 300 dpi grayscale to pdf format (OCR), using a Hp Scanjet 8250 Scanner. === Thesis (MEng (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 1992 === ENGLISH ABSTRACT: The large variety of turbo-machinery blade root geometries in
use in industry prompted the question if a optimum geometry could be found. An optimum blade root was defined as a root with a practical geometry which, when loaded, returns the minimum fillet stress concentration factor. A literature survey
on the subject provided guidelines but very little real data to work from. An initial optimization was carried out using a
formula developed by Heywood to determine loaded projection fillet stresses. The method was found to produce unsatisfactory
results, prompting a photoelastic investigation. This experimental optimization was conducted in two stages. A single tang defined load stage and a single tang in-rotor stage which modeled the practical situation. The defined load stage was undertaken in three phases. The first phase was a preliminary investigation, the second phase was a parameter optimization and
the third phase was a geometric optimization based on a material utilization optimization. This material optimization approach produced good results. From these experiments a practical optimum geometry was defined. A mathematical model which
predicts the fillet stress concentration factor for a given root
geometry is presented. The effect of expanding the single tang
optimum to a three tang root was examined. === AFRIKAANSE OPSOMMING: Die groot verskeidenheid lemwortelgeometrieë wat in turbomasjiene
gebruik word het die vraag na 'n optimum geometrie laat
ontstaan. Vir hierdie ondersoek is 'n optimum geometrie
gedefineer as 'n praktiese geometrie wat, as dit belas word, die
mimimum vloeistukspanningskonsentrasiefaktor laat ontstaan. 'n
Literatuur studie het riglyne aan die navorsing gegee maar het
wynig spesifieke en bruikbare data opgelewer. Die eerste
optimering is met die Heywood formule, wat vloeistukspannings
in belaste projeksies bepaal, aangepak. Die metode het nie
bevredigende resultate opgelewer nie. 'n Fotoelastiese
ondersoek het die basis vir verdere optimeering gevorm. Hierdie
eksperimentele optimering is in twee stappe onderneem. 'n
Enkelhaak gedefineerde lasgedeelte en 'n enkelhaak in-rotor
gedeelte het die praktiese situasie gemodeleer. Die
gedefineerde lasgedeelte is in drie fases opgedeel. Die eerste
fase was n voorlopige ondersoek. Die tweede fase was 'n
parameter optimering. 'n Geometrie optimering gebasseer op 'n
materiaal benuttings minimering het die derde fase uitgemaak.
Die materiaal optimerings benadering het goeie resultate
opgelewer. Vanuit hierdie eksperimente is 'n optimum praktiese
geometrie bepaal. 'n Wiskundige model is ontwikkel, wat die
vloeistukspanningskonsentrasiefaktor vir 'n gegewe
wortelgeometrie voorspel. Die resultaat van 'n geometriese
uitbreiding van die enkelhaaklemwortel na 'n driehaaklemwortel
op die spanningsverdeling is ondersoek.
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