Morphology of Crack Propagation

2 Morphological Aspects of Fatigue Crack Formation and Growth 

No stress Mild stress Severe stress No stress Mild stress Severe stress concentration concentration concentration concentration concentration concentration 

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Friedrich, K. (1978) Analysis of crack propagation in isotactic polypropylene with different morphology, Progr. Colloid Polymer Sci., 64, 103-112. 

Computer Simulation of Crack Propagation. A typical experimental procedure for investigating fracture consists in looking at the fracture surface with a scanning electron microscope (SEM) or a transmission electron microscope (TEM) (49,50). This provides us with the morphology at the time of fracture, which is useful information. However, the microscopic techniques do not tell us where and how the crack(s) which eventually led to fracture had started. 

Whatever its success may be, this model fails to account for different features of environmentally assisted cracking and particularly see in the absence of protective film (if any), the discontinuous character of the crack propagation, and the morphology of crack faces which have specific crystallographic features and do not exhibit significant traces of dissolution. 

This is the classic form of failure in elastic materials and consists of a relatively smooth mirror zone of crack propagation leading to a rougher zone of final failure due to multiple crack-initiation (comparable in morphology to Fig. 1.7). 

III. Molecular and Morphological Aspects of Crack Propagation Table 9.5. Mechano-chemistry of Solid Polymers Methods and Objectives... 

In this study specimens are collected from samples tested by the ESCR method and the morphology of cracks is investigated by scanning electron microscopy. The difference of morphology is observed, and the ESCR property is explained based on the observations. The observation of fracture surfaces especially allows the crack initiation location and the direction of crack propagation to be identified. 

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