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Fracture mechanics is the field of mechanics concerned with the study of the propagation of cracks in materials. It uses methods of analytical solid mechanics to calculate the driving force on a crack and those of experimental solid mechanics to characterize the material's resistance to fracture.
A crack growth equation is used for calculating the size of a fatigue crack growing from cyclic loads. The growth of a fatigue crack can result in catastrophic failure, particularly in the case of aircraft. When many growing fatigue cracks interact with one another it is known as widespread fatigue damage. A crack growth equation can be used to ...
The shear crack, shown in blue, propagates when tensile cracks, shown in red, grow perpendicular to the direction of the least principal stresses. The tensile cracks propagate a short distance then become stable, allowing the shear crack to propagate. [5] This type of crack propagation should only be considered an example.
The crack initiation range in metals is propagation, and there is a significant quantitative difference in rate while the difference appears to be less apparent with composites. [54] Fatigue cracks of composites may form in the matrix and propagate slowly since the matrix carries such a small fraction of the applied stress .
Microscopic material failure is defined in terms of crack initiation and propagation. Such methodologies are useful for gaining insight in the cracking of specimens and simple structures under well defined global load distributions. Microscopic failure considers the initiation and propagation of a crack.
In a 1961 paper, P. C. Paris introduced the idea that the rate of crack growth may depend on the stress intensity factor. [4] Then in their 1963 paper, Paris and Erdogan indirectly suggested the equation with the aside remark "The authors are hesitant but cannot resist the temptation to draw the straight line slope 1/4 through the data" after reviewing data on a log-log plot of crack growth ...
In a falling R-curve regime, as a crack propagates, the resistance to further crack propagation drops, and it requires less and less applied in order to achieve each subsequent increment of crack extension . Materials experiencing these conditions would exhibit highly unstable crack growth as soon as any initial crack began to propagate.
Intergranular fracture produced by crack propagation along grain boundaries. Embrittlement, or loss of ductility, is often accompanied by a change in fracture mode from transgranular to intergranular fracture. [4] This transition is particularly significant in the mechanism of impurity-atom embrittlement. [4]