Računski model za določitev nosilnosti velikih aksialnih trirednih valjčnih ležajev

Göncz, Peter

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Title:	Računski model za določitev nosilnosti velikih aksialnih trirednih valjčnih ležajev
Authors:	ID Göncz, Peter (Author) ID Glodež, Srečko (Mentor) More about this mentor... ID Ulbin, Miran (Comentor)
Files:	DR_Goncz_Peter_2013.pdf (20,61 MB) MD5: 220A072416EE96589CB5D24BAB03563E
Language:	Slovenian
Work type:	Dissertation
Typology:	2.08 - Doctoral Dissertation
Organization:	FS - Faculty of Mechanical Engineering
Abstract:	V predloženi doktorski disertaciji je prikazan računski model za določitev nosilnosti velikih aksialnih trirednih valjčnih ležajev. Jedro modela predstavlja matematično-analitični računski postopek za določitev porazdelitve notranjih kontaktnih sil pri obravnavanem tipu velikega aksialnega ležaja. Ta temelji na statičnem ravnovesju med zunanjo obremenitvijo ter notranjimi kontaktnimi silami med valjčki in tečinami ležajnih obročev. Računski model lahko upošteva vpliv poljubnega števila in geometrij valjčkov, nevzporednih relativnih pomikov ležajnih obročev in posledično neenakomerne kontaktne obremenitve valjčkov. Omogočeno je upoštevanje poljubnih kombinacij aksialnih zračnosti ležaja ter vnaprej definiranih strukturnih deformiranosti ležajnih obročev. Rezultati računskih primerov za ta dva dejavnika so pokazali, da lahko bistveno zmanjšata nosilnost ležaja. Za praktično uporabnost je bil model implementiran v računalniško kodo. V okviru določitve statične nosilnosti površinsko zakaljenih tečin je bil analiziran vpliv geometrije valjčkov treh tipov: cilindričnega, logaritemskega in delno profiliranega. Za ta namen je bila izvedena numerična parametrična analiza kontakta valjčkov in segmenta tečine, ki je omogočala določitev vplivov izbranih kriterijev mejne nosilnosti, debeline zakaljene plasti tečine ter neenakomernih kontaktnih obremenitev valjčkov. S pomočjo Basquinove enačbe je bila računsko določena dinamična nosilnost površinsko zakaljene tečine ležaja v območju velikocikličnega utrujanja. Doba trajanja tečine je bila pri tem določena na dva načina: (i) z uporabo materialnih parametrov, določenih pri R = −1 ter upoštevanjem vpliva srednje primerjalne napetosti z Goodmanovo enačbo; (ii) z uporabo materialnih parametrov, določenih pri R = −∞. V omejenem obsegu je bila opravljena eksperimentalna določitev dinamične nosilnosti površinsko zakaljene tečine velikega kotalnega ležaja na preizkuševališču za kotalno-kontaktno utrujanje.
Keywords:	kontaktni problemi, veliki aksialni ležaji, valjčni ležaji, nosilnost, utrujanje
Place of publishing:	[Maribor
Publisher:	P. Göncz]
Year of publishing:	2013
PID:	20.500.12556/DKUM-42927
UDC:	621.822.8:620.178.3(043.3)
COBISS.SI-ID:	270578176
NUK URN:	URN:SI:UM:DK:Z9QDTKOC
Publication date in DKUM:	02.12.2013
Views:	2536
Downloads:	358
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Categories:	KTFMB - FS
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Secondary language

Language:	English
Title:	Computational model for determination of load capacity of three-row roller slewing bearings
Abstract:	The topic of the doctoral thesis presented herein is a computational model for determination of load capacity of large three-row roller slewing bearings. The main part of the model is a mathematical method for determination of internal contact forces distribution in this type of slewing bearing. It is based on the static equilibrium between the external loads and the internal contact forces between the rollers and raceways. The calculation method can consider arbitrary number and geometries of rollers in both axial rows, non-parallel relative ring displacements and consecutively the misaligned roller contacts. Additionally, arbitrary combinations of axial internal clearances and predefined structural ring deformations can be considered. Results of practical example show that these two factors alone can substantially decrease the bearing’s load capacity. For practical usability, the method was implemented into a computer code. In the framework of static load capacity determination of the surface hardened raceway, three different types of roller geometries were analyzed: cylindrical, logarithmical and partially crowned. Numerical parametric analyses of the contact between the rollers and the raceway segment were carried out for this purpose. By these analyses the influence of different static capacity criterions, depths of surface hardened raceway and roller misalignments were studied. For the dynamic load capacity determination of the surface hardened raceway in the high cycle fatigue regime the Basquin expression was applied. For the fatigue lifetime calculations of the raceway two different approaches were used: (i) material parameters determined at R = −1 and consideration of the mean equivalent stress with the Goodman relation; (ii) material parameters experimentally determined at R = −∞. Additionally, an experimental determination of the dynamic load capacity of the surface hardened raceway of a slewing bearing was carried out on a rolling contact fatigue test bench in a limited extent.
Keywords:	contact problems, large slewing bearings, roller bearings, load carrying capacity, fatigue

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