Self-arresting cracks at notches in ductile cast iron

• Published in: Engineering fracture mechanics Vol. 102; pp. 146 - 155
• Main Authors: Zambrano, H.R., Härkegård, G.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.04.2013
• Subjects: Amplitudes; Cast iron; Crack arrest; Fatigue limit; Fracture mechanics; Microscopes; Nodular iron; Non-propagating crack; Notch sensitivity; Notches; Roots; Short fatigue-crack growth; Threshold stress-intensity range; Cast iron; Notches; Non-propagating crack; Threshold stress-intensity range; Fatigue limit; Crack arrest; Short fatigue-crack growth
• ISSN: 0013-7944; 1873-7315
• DOI: 10.1016/j.engfracmech.2012.11.008

► The following note has been added to the text: dimensions are in mm. Please check Figs. 2 and 8. ► The acronym SAC has been added to the nomenclature list. ► 52.2MPa has been changed by 52MPa in the text. In this research, an experimental study of the notch effect in ductile cast iron EN-GJS-400-18-LT has been performed. Double-edge notched specimens with different notch root radii were tested under fully reversed axial loading. The notch root was monitored with a travelling microscope. By judicious selection of the load amplitudes, self-arresting cracks were observed in most of the specimens. Two different models were used to analyse the growth of a short crack from the notch root. One model was a generalisation of El Haddad’s equation to short-crack growth in an inhomogeneous stress field. The other was a slightly modified version of a model by Härkegård based on El Haddad’s asymptotic solutions for shallow and deep cracks. Self-arresting cracks in the double-edge notched specimens were predicted in reasonable agreement with experimental observations. The two short-crack-growth models were also applied to literature fatigue data for notched rotating bend specimens of a similar type of ductile cast iron. Härkegård’s model predicted the notched fatigue limit in good agreement with reported observations.