Elastic deformation and the laws of friction

1957 ◽  
Vol 243 (1233) ◽  
pp. 190-205 ◽  
Keyword(s):  
Surface Topography ◽  
Elastic Deformation ◽  
Frictional Force ◽  
Metal Surfaces ◽  
Applied Load ◽  
Elastic Contact ◽  
Elastic Materials ◽  
General Law ◽  
Highly Elastic Materials

This paper examines whether the hypothesis of elastic deformation of surface protuberances is consistent with Amontons’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 proportional to the ⅔ 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 Amontons’s law would not be obeyed. However, conforming surfaces usually touch at many points, and it is shown that in these circumstances A 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 Amontons’s law is obeyed depends upon the surface topography. For highly elastic materials such as Perspex, Amontons’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.

A Study of Polymers. II. Dynamic Method of Studying Elastic Materials

1940 ◽  
Vol 13 (4) ◽  
pp. 898-904 ◽  
Author(s):  
Yu S. Lazurkin
Keyword(s):  
Elastic Deformation ◽  
Dynamic Tests ◽  
Elastic Materials ◽  
General Picture ◽  
High Frequencies ◽  
Dynamic Conditions ◽  
Automobile Tire ◽  
General Law ◽  
Long Time ◽  
Time Required

Abstract Most articles made from elastic substances are intended for service under dynamic conditions. Static methods of investigation are clearly insufficient for determining the behavior of elastic substances under dynamic conditions and therefore there has for a long time been a need for dynamic tests. In recent years several dynamic tests have been developed, and a number of investigations of elastic properties under dynamic conditions have been published. The works of Frumkin, Roelig, Kosten, Naunton and Waring and other investigators have established a series of relations in the behavior of elastic substances under dynamic conditions. However, the limited intervals of frequency and temperature in these experiments gave relations of peculiar character and even led to contradictions. Thus Naunton and Waring showed that, under dynamic conditions (at high frequencies), automobile tire casings act as solid hoops and, according to Roelig and Kosten, the relation between modulus and frequency, though still existing, is of relatively little importance. The development of a concept of the mechanism of highly elastic deformation, and in particular the disclosure of relaxation made it possible for Kornfel'd and Poznyak and Mikhai˘lov and Kirilina to demonstrate experimentally the existence of a more general law relating the phenomena. However, in their experiments, the frequency in both cases changed within narrow limits, and consequently these investigations too do not give a general picture of the behavior of elastic materials in relation to the frequency of deformation and temperature. The idea of highly elastic deformation, as well as that of relaxation, comes down to the fact that the magnitudes of the deformations observed depend on the relation between the time of action of the force and the time required for regrouping of the particles in the substance during the deformation.

Friction properties of highly elastic materials at high contact pressures

1973 ◽  
Vol 7 (1) ◽  
pp. 115-120
Author(s):  
G. M. Bartenev ◽  
V. V. Lavrent'ev ◽  
V. S. Voevodskii
Keyword(s):  
Elastic Materials ◽  
Contact Pressures ◽  
Highly Elastic Materials

Flow Phenomena in Rubber Samples

1950 ◽  
Vol 23 (1) ◽  
pp. 67-88
Author(s):  
Fritz Rössler
Keyword(s):  
Low Temperatures ◽  
Test Specimen ◽  
Room Temperature ◽  
Elastic Materials ◽  
Dead Weight ◽  
Point Change ◽  
Different Types ◽  
Flow Phenomena ◽  
High Degree ◽  
Highly Elastic Materials

Abstract A more extended investigation was made of the surprising flow phenomena which were found in an earlier study of rubber at low temperatures. The tensile apparatus was reconstructed so that a dead-weight load could be applied to the rubber test-specimen. Determinations of the dependence of the rate of flow on time of stressing, initial elongation, magnitude of the stress, and temperature showed that a simple law can be derived for expressing the flow phenomena. Yield point, change in color, and deterioration in physical properties, as well as the reversibility of these phenomena were investigated and are discussed. The phenomena of flow at room temperature are expressed by the same constants as at lower temperatures. Only the effective stress increases at low temperatures and only by this change does flow become perceptible. Different types of rubber were compared, and all showed approximately the same value for the flow constant. The essential characteristics of the flow phenomenon can be explained, on a basis of the theory of highly elastic materials, by their microliquid state of aggregation. This applies to the high degree of dependence of the mechanical properties of rubber on the temperature.

Transient waves in a layered anisotropic elastic medium

1985 ◽  
Vol 397 (1812) ◽  
pp. 67-85 ◽  
Keyword(s):  
Wave Propagation ◽  
General Solution ◽  
Applied Load ◽  
Layered Medium ◽  
Elastic Materials ◽  
Transient Waves ◽  
Anisotropic Elastic Medium ◽  
Unit Step ◽  
Stress Components ◽  
Anisotropic Elastic

Wave propagation in a periodically layered medium is studied in which each period consists of two layers of homogeneous anisotropic elastic materials. The layered medium occupies the half-space x ≥ 0 in which the x -axis is normal to the layers. Transient waves in the layered medium are generated by a unit step load in time applied at x = 0. A general solution that applies to any x is obtained in the form of a Laplace transform. Asymptotic solutions valid for large x are then deduced. If the applied load at x = 0 is in the direction of one of the polarization vectors for the layered medium determined here, the stress components propagate uncoupled asymptotically. For general loadings, there are three ‘heads of the pulses’, each of which is in the form of an Airy integral.

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