Fracture mechanics in design and service: ‘living with defects’ - Application of fracture mechanics to rubber articles, including tyres

1981 ◽  
Vol 299 (1446) ◽  
pp. 189-202 ◽  
Keyword(s):  
Fracture Mechanics ◽  
Crack Growth ◽  
Strain Energy ◽  
Tensile Failure ◽  
Practical Application ◽  
Complicated Fracture ◽  
Fracture Work

The use of a fracture mechanics approach, based on the rate of release of strain energy, to account for various features of the failure of vulcanized rubbers is outlined. The properties considered include those to which fracture mechanics is often applied — tear, tensile failure, crack growth and fatigue — and others to which its application is less usual — abrasion, ozone attack and cutting by sharp objects. The relation of macroscopically observed properties to the basic molecular strength of the material is also discussed. An example of a quantitative practical application of the rubber fracture work, to groove cracking in tyres, is then considered. Finally, the rather more complicated fracture that can occur in rubber—cord laminates is discussed and it is shown that the energetics approach can be applied to some features, at least, of this.

Factors Influencing the Strength of Rubbers

1975 ◽  
Vol 48 (5) ◽  
pp. 902-912 ◽  
Author(s):  
A. G. Thomas
Keyword(s):  
Fracture Mechanics ◽  
Crack Growth ◽  
Growth Characteristic ◽  
Tensile Failure ◽  
Razor Blade ◽  
New Approach ◽  
Surface Configuration ◽  
Strength Behavior ◽  
Base Of The Tongue ◽  
Good Agreement

Abstract The strength behavior of rubbers is discussed in terms of fracture mechanics which treats fatigue and tensile failure as crack growth processes from small flaws. Crack growth can be influenced by the presence of oxygen or ozone. The nature of the vulcanizing system affects strength : crosslinks probably rupture and reform under stress. A new approach to the problem of abrasion is presented using fracture mechanics. Schallamach has shown that rubber often develops a pattern of ridges perpendicular to the direction of abrasion. In the simplest case abrasion is produced by a line contact (e.g., a razor blade) which pulls a tongue of rubber from the ridge producing crack growth at the base of the tongue. Provided the surface configuration is in a steady state, the quantity of rubber abraded can be related quantitatively to the frictional force and the crack growth characteristic of the rubber on some reasonable assumptions. Good agreement with experiment is found for noncrystallizing rubbers but the behavior of strain crystallizing natural rubber suggests that crystallization cannot occur under the conditions used so that the rubber is not strengthened by this means.

Mechanics of Fracture in Two-Ply Laminates

1979 ◽  
Vol 52 (1) ◽  
pp. 96-109 ◽  
Author(s):  
R. F. Breidenbach ◽  
G. J. Lake
Keyword(s):  
Growth Rate ◽  
Fracture Mechanics ◽  
Crack Length ◽  
Crack Growth ◽  
Central Region ◽  
Growth Rates ◽  
Strain Energy ◽  
Reasonable Agreement ◽  
Growth Characteristics ◽  
Crack Growth Rates

Abstract This paper describes a study of fracture in two-ply rubber—cord composites subjected to repeated tensile deformations. Under the conditions used, failure occurs predominantly because of the growth of cracks between the plies. A fracture mechanics approach enables the rate of crack growth to be predicted in terms of the elastic properties and dimensions of the laminate, the magnitude of the deformations and the basic crack growth characteristics of the ply rubber. The theory indicates the growth rate to be determined by the strain energy released from the central region of the laminate and to be independent of crack length once this exceeds a small value. The latter feature has been verified experimentally and the magnitudes of the observed crack growth rates are in reasonable agreement with those predicted for various deformation cycles.

Application of Fracture Mechanics to Crack Growth in Rubber-Cord Laminates

2001 ◽  
Vol 74 (3) ◽  
pp. 509-524 ◽  
Author(s):  
G. J. Lake
Keyword(s):  
Fracture Mechanics ◽  
Energy Release Rate ◽  
Energy Release ◽  
Crack Growth ◽  
Release Rate ◽  
Strain Energy ◽  
Fatigue Cracks ◽  
Strain Energy Release ◽  
Energy Release Rates ◽  
Laminated Structures

Abstract The use of a fracture mechanics approach based on the strain energy release rate to assess failure due to the growth of fatigue cracks in rubber—cord laminated structures is discussed. The mechanics of crack propagation is considered for cracking either between the plies or around individual cords, and also for crack initiation and growth near cord ends. Energy release rates can be calculated approximately for each of these cases and enable the laminate results to be related to the independently measured crack growth characteristics of the rubber. Experimental energy release rate determinations, from compliance changes produced by propagating model inter-ply cracks by cutting, provide a check on the accuracy of the calculated energies. The approach identifies material properties relevant to laminate failure and indicates the effects of loading, design and construction parameters on the rate and nature of failure.

Effective Modeling of Fatigue Crack Growth in Pipelines

2012 ◽  
Author(s):  
Steven J. Polasik ◽  
Carl E. Jaske
Keyword(s):  
Fatigue Crack ◽  
Stress Intensity ◽  
Fatigue Crack Growth ◽  
Fracture Mechanics ◽  
Crack Growth ◽  
Growth Models ◽  
Critical Parameters ◽  
Operating Pressure ◽  
Mechanics Model ◽  
Key Variables

Pipeline operators must rely on fatigue crack growth models to evaluate the effects of operating pressure acting on flaws within the longitudinal seam to set re-assessment intervals. In most cases, many of the critical parameters in these models are unknown and must be assumed. As such, estimated remaining lives can be overly conservative, potentially leading to unrealistic and short reassessment intervals. This paper describes the fatigue crack growth methodology utilized by Det Norske Veritas (USA), Inc. (DNV), which is based on established fracture mechanics principles. DNV uses the fracture mechanics model in CorLAS™ to calculate stress intensity factors using the elastic portion of the J-integral for either an elliptically or rectangularly shaped surface crack profile. Various correction factors are used to account for key variables, such as strain hardening rate and bulging. The validity of the stress intensity factor calculations utilized and the effect of modifying some key parameters are discussed and demonstrated against available data from the published literature.

scholarly journals R-curve Evaluation of Copper and Nickel Single Crystals Using Atomistic Simulations

Crystals ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 441 ◽  
Author(s):  
Xiao Zhuo ◽  
Jang Kim ◽  
Hyeon Beom
Keyword(s):  
Energy Release Rate ◽  
Single Crystals ◽  
Crack Growth ◽  
Release Rate ◽  
Edge Crack ◽  
Strain Energy ◽  
Critical Strain ◽  
Strain Energy Release Rate ◽  
Strain Energy Release ◽  
Crack Growth Resistance

The technique of molecular statics (MS) simulation was employed to determine the crack growth resistance curve of Cu and Ni single crystals. Copper and Ni single crystal nanoplates with an edge crack subjected to a tensile displacement were simulated. Stress-displacement curves and snapshots of the atomic configuration corresponding to different displacement levels were presented to elucidate the deformation mechanism. It was observed that the edge crack propagated step by step in a brittle manner, and the amount of crack growth at each step was half the lattice parameter. Through an energy consideration, the critical strain energy release rate at the onset of crack propagation and the crack growth resistance were calculated. The crack growth resistance is larger than the critical strain energy release rate because of the crack growth effect.

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