The process of inserting a fatigue pre-crack can present difficulties, as it is important that the fatigue crack grows in a uniform fashion. If pre-cracking is performed at too high a stress intensity range then a large plastic zone can form at the pre-crack tip which may mask the behaviour of the actual material during the test. (W 17) (1)

Fatigue crack = Ruptura por fadiga

…The rate of change in the load line displacement and creep crack length at the end of the test depends on the point at which the test is interrupted. (W 29) (2)

Creep crack = Ruptura por fluência

During the tests, each replica was examined in an optical microscope to check crack initiation, or, if it had occurred, to measure the surface crack length. To determine the size of small cracks more accurately, some replicas were examined in a scanning electron microscope (SEM). (W 114) (3)

Surface crack =Ruptura na superfície

(1) The Effect of Notch Sharpness on the Fracture Toughness Determined from SENT Specimens

Philippa Moore 

TWI Ltd, Granta Park Great Abington, Cambridge, CB21 6AL, UK 

Paper presented at Proceedings of the ASME 2014 33rd International Conference on Ocean, Offshore and Arctic Engineering OMAE2014 June 8-13, 2014, San Francisco, California, USA. 

(2) Specimen geometry and size effects on the creep crack growth behaviour of P91 weldments

S. Maleki 

TWI Ltd

A. Mehmanparast, K. M. Nikbin 

Imperial College London

M. Yatomi 

IHI Corporation

Paper presented at 2013 ASME Pressure Vessels and Piping Conference. Paris, France, 14-18 July 2013. 

(3) Fatigue life prediction for toe ground welded joints

Yan-Hui Zhang and Stephen J Maddox

Structural Integrity Technology Group

TWI Limited

Granta Park

Great Abington

Cambridge

CB1 6AL, UK

Paper published in International Journal of Fatigue, Vol. 31, Issue 7, July 2009, 1124-1136.