Stress intensity factor approach energy

The energy method of Griffith and the stress intensity factor approach of Irwin are, perhaps, the most basic and often used of the fracture criteria. Therefore, they have been emphasized in this article. However, the reader should be aware that other approaches to the problem have gained considerable popularity in recent years, foremost among them the J-integral (19) and the crack-opening displacement methods (20). These two criteria have been extensively applied to the fracture of metals for which crack tip plasticity is significant. 

The energy-balance approach is generally the most applicable to flexible joints since, away from the crack tip, the adhesive or substrates may not exhibit linear-elastic behaviour and so the stress-intensity factor approach is invalid. The most conunon test methods are shown in Fig. 1. 

Fracture mechanics A J KINLOCH Basis energy balance and stress-intensity factor approaches... 

Because the stress intensity factor and energy release rate approaches both apply to linearly elastic components, they can, in fact, be related [21] through... 

A different approach from the strain-energy-release rate in the study of the fraction process is the analysis of the stress distribution arormd the crack tip. This gives the stress intensity factor or fracture toughness K, which for a sharp crack in an infinitely wide and elastic plate is given by... 

In the Fracture mechanics approach, subcritical debonding rate is determined, often as a function of a fracmre parameter such as the applied energy release rate, G. Paris was the first to use this method, and noted that the crack growth rate per cycle was related to the energy release rate (by way of the stress intensity factor) through a power law relationship of the form... 

ISO CD 13586, Plastic—Determination of energy per unit area of crack (Gc) and the critical stress intensity factor (Kc), linear elastic fracture mechanics approach, 2000. 

Here Kic denotes the critical value of the stress intensity factor. The approach is conceivable because theoretical analysis proves that, in spite of the divergence of the stress at the tip, the total elastically stored energy remains finite. 

A major feature of the continuum fracture mechanics approach is that the plane strain values of the fracture energy or the stress intensity factor for a given mode of loading should be independent of the geometry of the specimen employed for their evaluation. This is obviously required if the values of Gc and... 

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