The Role of the Constraint in the Case of Short Cracks


Article Preview

A two-parameter constraint-based fracture mechanics approach is used to explain the effect of the constraint on the apparently anomalous behavior of short fatigue cracks. The different levels of stress constraint are quantified by the T-stress, and microstructurally as well as mechanically short cracks are discussed. Short cracks generally behave more sensitively to the constraint than the long ones. It is shown that in most cases, the existence of short cracks goes hand in hand with an intrinsic loss of the constraint, which contributes to a decrease of their fatigue threshold values and accelerates their growth. In this paper, the above effect is quantified and conclusions concerning the applicability of the fracture mechanics parameters and approaches to the estimation of the residual fatigue life of structures are discussed.



Edited by:

Jaroslav Pokluda




P. Hutař et al., "The Role of the Constraint in the Case of Short Cracks", Materials Science Forum, Vol. 482, pp. 303-306, 2005

Online since:

April 2005




[1] Hutař P., Seitl S., Knésl Z., Quantification of the effect of specimen geometry on the fatigue crack growth response by two-parameter fracture mechanics, 13 th International Conference on the Strength of Materials, p.146, Budapest, (2003).


[2] Knésl Z., Seitl S., Hutař P., Accounting for effects of constraint on propagation of fatigue crack, Damage & Fracture mechanics VII, WIT press, pp.245-253, (2002).

[3] Murakami Y., Metal Fatigue: Effects of Small Defects and Nonmetallic Inclusions, Elsevier, (2002).

[4] Sherry, A.H., France C.C., Goldthorpe, M.R., Compendium of T-stress solutions for two and three dimensional cracked geometries, Fatigue Fract. Engng. Struct., Vol. 18, 141-155, (1995).


[5] Vecchio, R. S., Crompton, J. S., Hertzberg, R. W., The influence of specimen geometry on near threshold fatigue crack growth, Fatigue Fract. Engng Mater. Struct., Vol. 10, pp.333-342, (1987).