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Elastic deformation and the laws of friction
-160
LITER:\TUKE
AND
Authors’
Adhesion
of Solids:
Principles
CIJRRENT
EI’ENTS
VOL. 1 (ir)57/58)
Abstracts
and Applications
0. I-. ANDERSON (Mechanics Research Bell Telephone Laboratories) ---Bell Labs. Recovd, November 19,T7); (7 pp.; 7 fig., no ref.). See ak0.f. A#. Phys., 28 (1957) 923. The theory of adhesion between solids has now been well substantiated, and on the basis of this theory. research and development have resulted in a number of significant experiments and practical applications. At Bell Laboratories, a recent major outcome of this work has been the use of thermo-compression bonding to attach wire leads to brittle non-metals like silicon and germanium. This technique promises great simplifications in fabrication and improvements in electrical characteristics of semiconductor devices.
Electrical
Effects Accompanying
Plastics and Lubricated
the Stick-Slip
Phenomenon
of Sliding of Metals on
Surfaces
G. W. SOHL, J. GAYNOR, AND S. &I. SKINNER - Tra~zzs.A%. Sec. Me&. Engrs., 7’) (1957) rg63-70; (18 fig., II ref.), The electrical transients which accompany the stick-slip phenomenon in boundary lubrication have been investigated by an apparatus which permits simultaneous oscillographic measurement of any two of the following: the instantaneous load, the instantaneousfrictional drag, the electrical transient potentials during the stick-slip motion. The phenomenon has been investigated with unlubricated metal-metal contact using four metals in various combinations, lubricated metalmetal contact using various combinations of metals and five lubricants, and metal-plastic contact; in all cases, the contact was a sliding contact at low speed, since this accentuates the stick-slip phenomenon. Definite time correlation between the mechanical stick-slip and the electrical transients has been found. The characteristics of the electrical discharge appear to favor a chargedischarge mechanism rather than a thermoeiectric potential or a dielectric breakdown mechanism, although further experiments are necessary to provide unambiguous proof of such a conclusion. Certain related frictional experiments were performed which, however, also favor such a mechanism.
Elastic Deformation
and the Laws of Friction
J. F. ARCHARD (Research Laboratory, Associated Electrical Industries land) - Proc. Roy. Sot.. .4 243 (1957) 190-205; (II fig.; IQ ref.)
Ltd., Aldermaston,
Eng-
This paper examines whether the hypothesis of elastic deformation of surface protuberances is consistent with Amonton’s law, that the friction is proportional to the applied load. For a single elastic contact, the area of contact A is known to be proportiona to the 2/3 power of the load W. Since the frictional force is generally assumed to be proportional to A, it has been thought that in elastic deformation Amonton’s law would not be obeyed. However, conforming surfaces usually touch at many points, and it is shown that in these circumstances <4 and W become nearly proportional. Experiments are described which show that the general law is that the friction is proportional to the true area of contact; whether or not Amonton’s law is obeyed depends upon the surface topography. For highly elastic materials such as I’erspex, Amonton’s law is obeyed when contact is made at many points, and other relations between A and W are observed when the contacts are few. Experiments with lubricated brass specimens show that the same conclusions apply to carefully prepared or well run-in metal surfaces running in conditions where the damage is small.
The Lubrication A. W. CROOK land) --- PM.
of Rollers
(Research Laboratory, associated Electrical Industries Ltd., Aldermaston, Trans. Roy. Sot. (London), A z50 (1958) 387-409; (14 fig; 17 ref.)
Eng-
When lubricated rollers are run together they are separated by a hydrodynamically-formed oil film. The thickness of this film has been measured by a capacitance method up to loads of IOOO lb. per inch of face (1.76.10* dyn cm-l) for conditions of pure rolling and for conditions of rolling with sliding such as exist at the contacts of gear teeth. It has been found, at low loads, that the film thickness varies inversely with load and proportionately with speed, as simple hydrodyna-
LITER:\TUKE
AND
Authors’
Adhesion
of Solids:
Principles
CIJRRENT
EI’ENTS
VOL. 1 (ir)57/58)
Abstracts
and Applications
0. I-. ANDERSON (Mechanics Research Bell Telephone Laboratories) ---Bell Labs. Recovd, November 19,T7); (7 pp.; 7 fig., no ref.). See ak0.f. A#. Phys., 28 (1957) 923. The theory of adhesion between solids has now been well substantiated, and on the basis of this theory. research and development have resulted in a number of significant experiments and practical applications. At Bell Laboratories, a recent major outcome of this work has been the use of thermo-compression bonding to attach wire leads to brittle non-metals like silicon and germanium. This technique promises great simplifications in fabrication and improvements in electrical characteristics of semiconductor devices.
Electrical
Effects Accompanying
Plastics and Lubricated
the Stick-Slip
Phenomenon
of Sliding of Metals on
Surfaces
G. W. SOHL, J. GAYNOR, AND S. &I. SKINNER - Tra~zzs.A%. Sec. Me&. Engrs., 7’) (1957) rg63-70; (18 fig., II ref.), The electrical transients which accompany the stick-slip phenomenon in boundary lubrication have been investigated by an apparatus which permits simultaneous oscillographic measurement of any two of the following: the instantaneous load, the instantaneousfrictional drag, the electrical transient potentials during the stick-slip motion. The phenomenon has been investigated with unlubricated metal-metal contact using four metals in various combinations, lubricated metalmetal contact using various combinations of metals and five lubricants, and metal-plastic contact; in all cases, the contact was a sliding contact at low speed, since this accentuates the stick-slip phenomenon. Definite time correlation between the mechanical stick-slip and the electrical transients has been found. The characteristics of the electrical discharge appear to favor a chargedischarge mechanism rather than a thermoeiectric potential or a dielectric breakdown mechanism, although further experiments are necessary to provide unambiguous proof of such a conclusion. Certain related frictional experiments were performed which, however, also favor such a mechanism.
Elastic Deformation
and the Laws of Friction
J. F. ARCHARD (Research Laboratory, Associated Electrical Industries land) - Proc. Roy. Sot.. .4 243 (1957) 190-205; (II fig.; IQ ref.)
Ltd., Aldermaston,
Eng-
This paper examines whether the hypothesis of elastic deformation of surface protuberances is consistent with Amonton’s law, that the friction is proportional to the applied load. For a single elastic contact, the area of contact A is known to be proportiona to the 2/3 power of the load W. Since the frictional force is generally assumed to be proportional to A, it has been thought that in elastic deformation Amonton’s law would not be obeyed. However, conforming surfaces usually touch at many points, and it is shown that in these circumstances <4 and W become nearly proportional. Experiments are described which show that the general law is that the friction is proportional to the true area of contact; whether or not Amonton’s law is obeyed depends upon the surface topography. For highly elastic materials such as I’erspex, Amonton’s law is obeyed when contact is made at many points, and other relations between A and W are observed when the contacts are few. Experiments with lubricated brass specimens show that the same conclusions apply to carefully prepared or well run-in metal surfaces running in conditions where the damage is small.
The Lubrication A. W. CROOK land) --- PM.
of Rollers
(Research Laboratory, associated Electrical Industries Ltd., Aldermaston, Trans. Roy. Sot. (London), A z50 (1958) 387-409; (14 fig; 17 ref.)
Eng-
When lubricated rollers are run together they are separated by a hydrodynamically-formed oil film. The thickness of this film has been measured by a capacitance method up to loads of IOOO lb. per inch of face (1.76.10* dyn cm-l) for conditions of pure rolling and for conditions of rolling with sliding such as exist at the contacts of gear teeth. It has been found, at low loads, that the film thickness varies inversely with load and proportionately with speed, as simple hydrodyna-