Kinetic concept of the strength of solids

Zhurkov, S. N.

doi:10.1007/bf00962961

Cited by 320 publications

(255 citation statements)

References 2 publications

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“…[24,25]. From the above it can be seen that, by the end of the 1950s, the stress-augmented thermal activation approach pioneered by Prandtl and Eyring had been successfully used in models of plastic deformation, liquid viscosity, kinetic friction, and chemical bond dissociation.…”

Section: Early Historymentioning

confidence: 99%

“…Then, in the 1970s, Hirst and Moore [52−55] and Johnson and Tevaarwerk [56,57] showed that disc machine friction measurements could be very well explained by Eyring's shear thinning model as expressed in Eq. (24). In such measurements, and indeed all measurements at a combination of high viscosity and high shear rate, it is important to eliminate thermal effects and this was done initially by studying very low sliding speed conditions and later by applying an isothermal correction [58,59].…”

Section: Ehd Frictionmentioning

confidence: 99%

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Stress-augmented thermal activation: Tribology feels the force

2018

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Abstract:In stress-augmented thermal activation, the activation energy barrier that controls the rate of atomic and molecular processes is reduced by the application of stress, with the result that the rate of these processes increases exponentially with applied stress. This concept has particular relevance to Tribology, and since its development in the early twentieth century, it has been applied to develop important models of plastic flow, sliding friction, rheology, wear, and tribochemistry. This paper reviews the development of stress-augmented thermal activation and its application to all of these areas of Tribology. The strengths and limitations of the approach are then discussed and future directions considered. From the scientific point of view, the concept of stress-augmented thermal activation is important since it enables the development of models that describe macroscale tribological performance, such as friction coefficient or tribofilm formation, in terms of the structure and behaviour of individual atoms and molecules. This both helps us understand these processes at a fundamental level and also provides tools for the informed design of lubricants and surfaces.

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Section: Early Historymentioning

confidence: 99%

Section: Ehd Frictionmentioning

confidence: 99%

Stress-augmented thermal activation: Tribology feels the force

2018

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“…Accordingly, there is a metastable (labil) region between the two points. In the regions between these two points, during displacement n Zhurkov [28] Activation barrier height (J) from C to C', for example, there are three equilibrium states, F 0 , F 00 and F 000 , two of which are stable. The energy of the system at some point is r FðnÞdn and is therefore given by the area under the curve.…”

Section: Prandtl-tomlinson Model For Sliding Frictionmentioning

confidence: 99%

“…In subsequent years, this was extended by Coleman to describe polymer creep failure [27] and Zhurkov to model the fracture properties of a wide range of materials including metals, polymers and ceramics [28]. Zhurkov considered the fracture of a solid to be a timedependent process whose rate is determined by mechanical stress and temperature and related the time to fracture to the applied stress, r, in a form that will, by now, be familiar to the reader:…”

Section: Fracture Modelsmentioning

confidence: 99%

On the Commonality Between Theoretical Models for Fluid and Solid Friction, Wear and Tribochemistry

2015

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Tribology is concerned with the influence of mechanically applied forces on interfacial phenomena that accompany and control sliding. A wide range of models has been developed to describe these phenomena, which include frictional dissipation, wear and tribochemical reactions. This paper shows that these apparently disparate models are based on the same fundamental concept that an externally applied force accelerates the rate of thermal transition of atoms or molecules across energy barriers present in solid and liquid materials, thereby promoting flow, slip or bond cleavage. Such ''stress-assisted'' effects and the associated thermal activation concepts were developed independently and in different forms by Prandtl (Z Angew Math Mech 8:85, 1928) and Eyring (J Chem Phys 4(4): [283][284][285][286][287][288][289][290][291] 1936). These two works have underpinned subsequent theories of dry friction, boundary lubrication, EHD rheology, tribochemistry and nanoscale wear modelling. This paper first reviews the historical development of the concepts, focussing in particular on the models of Prandtl and Eyring and how they have subsequently been used and adapted by others. The two approaches are then compared and contrasted, noting that although superficially similar, they contain quite different assumptions and constraints. First, the Prandtl model assumes that the force is exerted through a compliant spring, while constant force sliding is assumed by Eyring. Second, different approximations are made in the two models to describe the change in energy barrier with external force. Prandtl explores the asymptotic behaviour of the energy barrier as the applied force become sufficiently high to reduce it to zero, while Eyring assumes that the energy barrier is reduced by an amount equal to the external work carried out on the system. The theoretical underpinnings of these differences are discussed along with the implications of compliant coupling and constant force sliding on the velocity and temperature dependence of the friction forces for the two models.

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“…Zhurkov [59] presented on the first models to predict materials lifetime t f (except for very small stresses) in terms of a constant stress level σ,…”

Section: Kinetic Rate Theorymentioning

confidence: 99%

Time-dependent failure criteria for lifetime prediction of polymer matrix composite structures

Guedes

2011

Creep and Fatigue in Polymer Matrix Composites

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The use of fibre -reinforced polymers in civil construction applications originated structures with a high specific stiffness and strength. Although these structures usually present a high mechanical performance, their strength and stiffness may decay significantly over time. This is mainly due to the viscoelastic nature of the matrix, damage accumulation and propagation within the matrix and fibre breaking. One serious consequence, as a result of static fatigue (creep failure), is a premature failure which is usually catastrophic. However in civil engineering applications, the structural components are supposed to remain in service for 50 years or more in safety conditions.One argument used to replace steel by polymer-matrix composites is its superior corrosion resistance. Yet stress corrosion of glass fibre s takes place as soon as moisture reaches the fibre by absorption. This phenomenon accelerates fibre breaking. In most 2 civil engineering applications, glass-fibre reinforced polymers (GRP) are the most common especially because raw material is less expensive.The lack of full understanding of the fundamental parameters controlling long-term materials performance necessarily leads to over-design and, furthermore, inhibits greater utilization. In this context, lifetime prediction of these structures is an important issue to be solved before wider dissemination of civil engineering applications can take place. As an example, standards dealing with certification of GRP pipes require at least 10000 hours of testing for a high number of specimens. Even though these strong requirements may be foreseen as reasonable, concerning the safety of civil engineering applications, they severely restrict the improvement and innovation of new products.The present chapter reviews some theoretical approaches for long-term criteria. Timedependent failure criteria will be presented and developed for practical applications and illustrated with experimental cases.

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Kinetic concept of the strength of solids

Cited by 320 publications

References 2 publications

Stress-augmented thermal activation: Tribology feels the force

Stress-augmented thermal activation: Tribology feels the force

On the Commonality Between Theoretical Models for Fluid and Solid Friction, Wear and Tribochemistry

Time-dependent failure criteria for lifetime prediction of polymer matrix composite structures

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