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A study of erosion between two parallel surfaces oscillating at close proximity in liquids
CORNIGLION, J. The p r a c t i c a l applications of the t h e o r e t i c a l studies to the t i l t e d pad g a s b e a r i n g . P r o c e e d i n g s of the I n s t i t u t i o n of M e c h a n i c a l E n g i n e e r s , 181, P a r t 1,No. 13 (1967) To exploit the known a d v a n t a g e s of gas b e a r i n g s , it is n e c e s s a r y to be able to o p t i m i s e each individual design. The n o n l i n e a r i t y of the b a s i c Reynolds equation m a k e s this difficult, while the application of n u m e r i c a l m e t h o d s is tedious and expensive. Analytical solution can he obtained by making c e r t a i n b a s i c a s s u m p t i o n s and U n e a r i z i n g the equation. An i n t e r e s t i n g way to l i n e a r i z e the Reynolds equation is the ph solution found by A u s m a n on his work on plain j o u r n a l b e a r ings. An extension of this method has been done by P i t t s f o r tilting pad b e a r i n g s . T h e aim of this p a p e r is to c o m p a r e the a n a l y t i c a l solution with the e x p e r i m e n t a l r e s u l t s , and so a s c e r t a i n the validity of the h y p o t h e s i s . During th/e e x p e r i m e n t s the influence of the p a r a m e t e r s (load, speed, b e a r i n g size, c l e a r a n c e and pivot location) on the s h a p e and t h i c k n e s s of the gas film h a s been studied. It i s shown how a choice of pad may be m a d e to fulfil a c e r t a i n r e q u i r e m e n t . (Tribology 1968, a b s t r a c t 8)
D O T T E R W E I C H , E. Grease-lubricated sliding-contact b e a r i n g s . Schmiertechnik, Sept-Oct, p. 248 (1967) Full lubrication of greased sliding contact bearings can be obtained over a wide range of speeds and stresses provided a continuous m i n i m u m supply of grease, which is less than the equivalent amount of oil,is available (eg 500g/hr-m 2 at 20kg/cm 2 and lm/sec). Heat dissipation is thus difficultand sliding speeds are probably limited to 2m/sec. The design and calculation of the bearing should allow for the anticipated part fillingonly of the gap. Friction and displacement are similar to those in oil-lubricated bearings and can be calculated on the s a m e basis if the viscosity of the grease is accurately known. The Vogelphol transformation provides a good check of the reliabilityof a bearing. A restriction on types and closer tolerances are desirable future developments. The greater play, reduced enveloping angle and the sensitivity of the grease to various conditions are disadvantageous compared to oil lubrication. Confirmation of the findings is looked for. (Tribology 1968, abstract 9)
DYSON, A. I n v e s t i g a t i o n of t h e d i s c h a r g e - v o l t a g e m e t h o d of m e a s u r ing the t h i c k n e s s of oil f i l m s f o r m e d in a disc m a c h i n e under conditions of e l a s t o h y d r o d y n a m i c lubrication. P r o c e e d i n g s of the Institution of M e c h a n i c a l E n g i n e e r s , 181, P a r t 1,No.23 (1967) It is r e p o r t e d that the ' d i s c h a r g e - v o l t a g e ' method o f f e r s a s i m p l e m e a n s of m e a s u r i n g the t h i c k n e s s of oil f i l m s b e tween moving, m e t a l s u r f a c e s . To c o n f i r m t h i s r e p o r t it is n e c e s s a r y to c o m p a r e d i s c h a r g e - v o l t a g e m e a s u r e m e n t s with film ~hickness m e a s u r e d by an a l t e r n a t i v e method. U n d e r e l a s t o h y d r o d y n a m i c conditions a s u i t a b l e a l t e r n a t i v e way of e s t i m a t i n g the t h i c k n e s s of oil f i l m s between m o v i n g m e t a l s u r f a c e is to m e a s u r e the e l e c t r i c a l capacity b e t w e e n t h e m . T h i s method has been applied to a disc m a c h i n e and the film t h i c k n e s s obtained in t h i s way c o m p a r e d with the r e s u l t s of d i s c h a r g e - v o l t a g e d e t e r m i n a t i o n s . It was found that t h e r e w a s s o m e r e l a t i o n between d i s c h a r g e - v o l t a g e and film t h i c k n e s s but that, in g e n e r a l , t h i s r e l a t i o n was n o n - l i n e a r and d e pendent on the s l i d e / r o l l r a t i o and on the t e m p e r a t u r e . It is t h e r e f o r e concluded that the d i s c h a r g e - v o l t a g e does not m e a s u r e the t h i c k n e s s of oil f i l m s in the s i m p l e way s u g g e s ted; t h e r e w e r e some i n d i c a t i o n s that it m a y be p o s s i b l e to u s e it to m e a s u r e r e l a t i v e l y thick f i l m s , of the o r d e r of 40 ~in (1 ~m) or t h i c k e r , at high s l i d e / r o l l r a t i o s . (Tribology 1968, a b s t r a c t 10)
60
TRIBOLOGY J a n u a r y 1968
ELROD, G. H., McCABE, J. T. AND CHU, T . Y . Determtn*tton of g a s - b e a r i n g s t a b i l i t y by r e s p o n s e to a s t e p - j u m p . T r a n s a c t i o n s of the A m e r i c a n Society of M e c h a n i c a l E n g i n e e r s , J o u r n a l of L u b r i c a t i o n Technology, 89, S e r i e s F, No. 4, p. 493 (1967) A p r o c e d u r e in which the b e a r i n g film is d e s c r i b e d by i t s r e s p o n s e to s t e p - j u m p d i s p l a c e m e n t s is applied to i n v e s t i gate the s t a b i l i t y of a g a s b e a r i n g . The step r e s p o n s e s a r e u s e d in a s y s t e m of d y n a m i c a l equations. A 'growth f a c t o r ' is d e t e r m i n e d f o r each d e g r e e of f r e e d o m and t h i s is u s e d f o r s t a b i l i t y d e t e r m i n a t i o n . Solutions a r e p r e s e n t e d f o r an infinitely long s l e e v e b e a r i n g and f o r a s y s t e m c o n s i s t i n g of two e q u a l l y - l o a d e d long s l e e v e b e a r i n g s . (Tribology 1968, a b s t r a c t 1 I)
ELROD, H. G. AND NG, C. W. A t h e o r y f o r t u r b u l e n t fluid f i l m s and i t s a p p l i c a t i o n to b e a r i n g s . T r a n s a c t i o n s of the A m e r i c a n Society of M e c h a n i c a l E n g i n e e r s , J o u r n a l of L u b r i c a t i o n Technology, 89, S e r i e s E, No. 3, p. 346 (1967) A t u r b u l e n t l u b r i c a t i o n a n a l y s i s is d e r i v e d which i n c o r p o r a t e s s o m e w e l l - e s t a b l i s h e d f a c t s of t u r b u l e n t s h e a r flow. Coefficients f o r the g e n e r a l i s e d R e y n o l d s equation a r e d e v e l o ped, and c o m p u t a t i o n p r o c e d u r e s f o r the c h a r a c t e r i s t i c s of turbulent, self-acting bearings are presented. The non-linear a n a l y s i s i s quite g e n e r a l and v a l i d for s e l f - a c t i n g ( h y d r o dynamic), e x t e r n a l l y p r e s s u r i z e d and h y b r i d b e a r i n g s . R e c o m m e n d a t i o n s c o n c e r n i n g the a n a l y s i s of the t h r e e t y p e s of b e a r i n g a r e given, and c o m p a r i s o n s between the d e s c r i b e d t e c h n i q u e and the s t a n d a r d l i n e a r i z e d a p p r o a c h a r e made. (Tribology 1968, a b s t r a c t 12)
ENDO, K., OKADA, T. AND NAKASHIMA, M A study of e r o s i o n b e t w e e n two p a r a l l e l s u r f a c e s o s c i l l a t i n g at c l o s e p r o x i m i t y in liquids. T r a n s a c t i o n s of the A m e r i c a n Society of M e c h a n i c a l E n g i n e e r s , J o u r n a l of Lub r i c a t i o n Technology, 89, S e r i e s E, No. 3, p. 229 (1967) A disc of s t a i n l e s s s t e e l i s a r r a n g e d to o s c i l l a t e in c l o s e p r o x i m i t y to a p l a n e s u r f a c e while s u b m e r g e d in a fluid bath. The m a t e r i a l of the p l a n e s u r f a c e is v a r i e d along with the fluid used. The s p e c i m e n s s u f f e r s u r f a c e d a m a g e due to s u b - s u r f a c e fatigue and c a v i t a t i o n . T e s t s a r e conducted with s p e c i m e n s having s u r f a c e l a y e r s of b e a r i n g alloy and c r a c k s a r e found to appear, followed by flaking of the alloy l a y e r . The f o r m s of d a m a g e e n c o u n t e r e d a r e i l l u s t r a t e d with p h o t o g r a p h s and d i s c u s s e d at s o m e length. (Tribology 1968, a b s t r a c t 13) FIX, G. J. A N D P A S L E Y , P. R. Incompressible elastic viscous lubricants in continuoussleeve journal bearings. Transactions of the American Society of Mechanical Engineers, Journal of Applied Mechanics, 34, Series E, No. 3, p. 579 (1967) The effects of elasticity in a lubricating fluid on the performance of the bearing are found by a perturbation technique. An incompressible Maxwell-type fluid with a small elastic effect operating in a continuous sleeve journal is considered. A relationship is given for external lateral load on the journal and eccentricity. The solution shows that when the fluid has elastic effects the classical normality between the eccentric displacement and lateral loading expected for an incompressible fluid is not preserved. (Tribology 1968, abstract 14)
GARNELL,
P.
Lubrication and w e a r in rolling contact. Further investi-
gations of the mechanics of roller bearings. Proceedings of the Institution of Mechanical Engineers, 181, Part 1, No. 16 (1967) T h i s p a p e r d i s c u s s e s the effects of m i s a l i g n m e n t and s u r face f i n i s h on r e s i s t a n c e m e a s u r e m e n t s and s p e c u l a t e s on the i n t e r p r e t a t i o n of r e s i s t a n c e r e c o r d s , e s p e c i a l l y at v e r y s m a l l film t h i c k n e s s e s . An a t t e m p t is m a d e to a s s e s s the h y s t e r e s i s l o s s in r o l l i n g , and t h i s is found to b e a p p r e c i a b l e only at v e r y heavy loads. (Tribology 1968, a b s t r a c t 15)
D O T T E R W E I C H , E. Grease-lubricated sliding-contact b e a r i n g s . Schmiertechnik, Sept-Oct, p. 248 (1967) Full lubrication of greased sliding contact bearings can be obtained over a wide range of speeds and stresses provided a continuous m i n i m u m supply of grease, which is less than the equivalent amount of oil,is available (eg 500g/hr-m 2 at 20kg/cm 2 and lm/sec). Heat dissipation is thus difficultand sliding speeds are probably limited to 2m/sec. The design and calculation of the bearing should allow for the anticipated part fillingonly of the gap. Friction and displacement are similar to those in oil-lubricated bearings and can be calculated on the s a m e basis if the viscosity of the grease is accurately known. The Vogelphol transformation provides a good check of the reliabilityof a bearing. A restriction on types and closer tolerances are desirable future developments. The greater play, reduced enveloping angle and the sensitivity of the grease to various conditions are disadvantageous compared to oil lubrication. Confirmation of the findings is looked for. (Tribology 1968, abstract 9)
DYSON, A. I n v e s t i g a t i o n of t h e d i s c h a r g e - v o l t a g e m e t h o d of m e a s u r ing the t h i c k n e s s of oil f i l m s f o r m e d in a disc m a c h i n e under conditions of e l a s t o h y d r o d y n a m i c lubrication. P r o c e e d i n g s of the Institution of M e c h a n i c a l E n g i n e e r s , 181, P a r t 1,No.23 (1967) It is r e p o r t e d that the ' d i s c h a r g e - v o l t a g e ' method o f f e r s a s i m p l e m e a n s of m e a s u r i n g the t h i c k n e s s of oil f i l m s b e tween moving, m e t a l s u r f a c e s . To c o n f i r m t h i s r e p o r t it is n e c e s s a r y to c o m p a r e d i s c h a r g e - v o l t a g e m e a s u r e m e n t s with film ~hickness m e a s u r e d by an a l t e r n a t i v e method. U n d e r e l a s t o h y d r o d y n a m i c conditions a s u i t a b l e a l t e r n a t i v e way of e s t i m a t i n g the t h i c k n e s s of oil f i l m s between m o v i n g m e t a l s u r f a c e is to m e a s u r e the e l e c t r i c a l capacity b e t w e e n t h e m . T h i s method has been applied to a disc m a c h i n e and the film t h i c k n e s s obtained in t h i s way c o m p a r e d with the r e s u l t s of d i s c h a r g e - v o l t a g e d e t e r m i n a t i o n s . It was found that t h e r e w a s s o m e r e l a t i o n between d i s c h a r g e - v o l t a g e and film t h i c k n e s s but that, in g e n e r a l , t h i s r e l a t i o n was n o n - l i n e a r and d e pendent on the s l i d e / r o l l r a t i o and on the t e m p e r a t u r e . It is t h e r e f o r e concluded that the d i s c h a r g e - v o l t a g e does not m e a s u r e the t h i c k n e s s of oil f i l m s in the s i m p l e way s u g g e s ted; t h e r e w e r e some i n d i c a t i o n s that it m a y be p o s s i b l e to u s e it to m e a s u r e r e l a t i v e l y thick f i l m s , of the o r d e r of 40 ~in (1 ~m) or t h i c k e r , at high s l i d e / r o l l r a t i o s . (Tribology 1968, a b s t r a c t 10)
60
TRIBOLOGY J a n u a r y 1968
ELROD, G. H., McCABE, J. T. AND CHU, T . Y . Determtn*tton of g a s - b e a r i n g s t a b i l i t y by r e s p o n s e to a s t e p - j u m p . T r a n s a c t i o n s of the A m e r i c a n Society of M e c h a n i c a l E n g i n e e r s , J o u r n a l of L u b r i c a t i o n Technology, 89, S e r i e s F, No. 4, p. 493 (1967) A p r o c e d u r e in which the b e a r i n g film is d e s c r i b e d by i t s r e s p o n s e to s t e p - j u m p d i s p l a c e m e n t s is applied to i n v e s t i gate the s t a b i l i t y of a g a s b e a r i n g . The step r e s p o n s e s a r e u s e d in a s y s t e m of d y n a m i c a l equations. A 'growth f a c t o r ' is d e t e r m i n e d f o r each d e g r e e of f r e e d o m and t h i s is u s e d f o r s t a b i l i t y d e t e r m i n a t i o n . Solutions a r e p r e s e n t e d f o r an infinitely long s l e e v e b e a r i n g and f o r a s y s t e m c o n s i s t i n g of two e q u a l l y - l o a d e d long s l e e v e b e a r i n g s . (Tribology 1968, a b s t r a c t 1 I)
ELROD, H. G. AND NG, C. W. A t h e o r y f o r t u r b u l e n t fluid f i l m s and i t s a p p l i c a t i o n to b e a r i n g s . T r a n s a c t i o n s of the A m e r i c a n Society of M e c h a n i c a l E n g i n e e r s , J o u r n a l of L u b r i c a t i o n Technology, 89, S e r i e s E, No. 3, p. 346 (1967) A t u r b u l e n t l u b r i c a t i o n a n a l y s i s is d e r i v e d which i n c o r p o r a t e s s o m e w e l l - e s t a b l i s h e d f a c t s of t u r b u l e n t s h e a r flow. Coefficients f o r the g e n e r a l i s e d R e y n o l d s equation a r e d e v e l o ped, and c o m p u t a t i o n p r o c e d u r e s f o r the c h a r a c t e r i s t i c s of turbulent, self-acting bearings are presented. The non-linear a n a l y s i s i s quite g e n e r a l and v a l i d for s e l f - a c t i n g ( h y d r o dynamic), e x t e r n a l l y p r e s s u r i z e d and h y b r i d b e a r i n g s . R e c o m m e n d a t i o n s c o n c e r n i n g the a n a l y s i s of the t h r e e t y p e s of b e a r i n g a r e given, and c o m p a r i s o n s between the d e s c r i b e d t e c h n i q u e and the s t a n d a r d l i n e a r i z e d a p p r o a c h a r e made. (Tribology 1968, a b s t r a c t 12)
ENDO, K., OKADA, T. AND NAKASHIMA, M A study of e r o s i o n b e t w e e n two p a r a l l e l s u r f a c e s o s c i l l a t i n g at c l o s e p r o x i m i t y in liquids. T r a n s a c t i o n s of the A m e r i c a n Society of M e c h a n i c a l E n g i n e e r s , J o u r n a l of Lub r i c a t i o n Technology, 89, S e r i e s E, No. 3, p. 229 (1967) A disc of s t a i n l e s s s t e e l i s a r r a n g e d to o s c i l l a t e in c l o s e p r o x i m i t y to a p l a n e s u r f a c e while s u b m e r g e d in a fluid bath. The m a t e r i a l of the p l a n e s u r f a c e is v a r i e d along with the fluid used. The s p e c i m e n s s u f f e r s u r f a c e d a m a g e due to s u b - s u r f a c e fatigue and c a v i t a t i o n . T e s t s a r e conducted with s p e c i m e n s having s u r f a c e l a y e r s of b e a r i n g alloy and c r a c k s a r e found to appear, followed by flaking of the alloy l a y e r . The f o r m s of d a m a g e e n c o u n t e r e d a r e i l l u s t r a t e d with p h o t o g r a p h s and d i s c u s s e d at s o m e length. (Tribology 1968, a b s t r a c t 13) FIX, G. J. A N D P A S L E Y , P. R. Incompressible elastic viscous lubricants in continuoussleeve journal bearings. Transactions of the American Society of Mechanical Engineers, Journal of Applied Mechanics, 34, Series E, No. 3, p. 579 (1967) The effects of elasticity in a lubricating fluid on the performance of the bearing are found by a perturbation technique. An incompressible Maxwell-type fluid with a small elastic effect operating in a continuous sleeve journal is considered. A relationship is given for external lateral load on the journal and eccentricity. The solution shows that when the fluid has elastic effects the classical normality between the eccentric displacement and lateral loading expected for an incompressible fluid is not preserved. (Tribology 1968, abstract 14)
GARNELL,
P.
Lubrication and w e a r in rolling contact. Further investi-
gations of the mechanics of roller bearings. Proceedings of the Institution of Mechanical Engineers, 181, Part 1, No. 16 (1967) T h i s p a p e r d i s c u s s e s the effects of m i s a l i g n m e n t and s u r face f i n i s h on r e s i s t a n c e m e a s u r e m e n t s and s p e c u l a t e s on the i n t e r p r e t a t i o n of r e s i s t a n c e r e c o r d s , e s p e c i a l l y at v e r y s m a l l film t h i c k n e s s e s . An a t t e m p t is m a d e to a s s e s s the h y s t e r e s i s l o s s in r o l l i n g , and t h i s is found to b e a p p r e c i a b l e only at v e r y heavy loads. (Tribology 1968, a b s t r a c t 15)