Print ISSN: 1681-6900

Online ISSN: 2412-0758

Keywords : Crack growth

Study of Short Cracks Growth Behavior for Duralumin 7075- T6 Enhanced by Artificial Ageing as Thermal and Chemical Treatments Under Rotating Bending Loading

Mustafa Sami Abdullateef

Engineering and Technology Journal, 2013, Volume 31, Issue 11, Pages 2166-2182

The fatigue life of ductile metals is controlled mainly by the propagation life of a short surface crack; to clarify the growth behavior of short cracks is crucial factor to the safe design of smooth surface members. However, little has been reported on the growth behavior of short surface cracks in thermal-chemical treated duralumin. In the present study, stress-controlled fatigue tests (under rotating bending load) for 70 hours artificial aged duralumin 7075-T6 without chemical treatment case (1) and with chemical treatment case (2). The growth behavior of short cracks was monitored by a plastic replication technique and the surface damage (short crack propagation) during cyclic stressing was observed by optical microscopy. The physical background of fatigue damage for case (1) and case (2) was discussed from the viewpoints of the initiation and growth behavior of short cracks.

Crack Growth Model for Estimating the Fatigue Life under Variable loading

Hassan Abd- ALRsoul; Basim H. Abbas; Khairallah S. Jabur

Engineering and Technology Journal, 2011, Volume 29, Issue 13, Pages 2773-2782

This paper examines the fatigue short and long cracks behaviour in 2024 T4 aluminum alloy under rotating bending loading and stress ratio R = -1. In the short cracks region, cracks grow initially at a fast rate but deceleration occurs quickly and, depending on the stress level, they either arrest or are temporarily halted at a critical length. This critical length is shown to conincide with the value of the microstructure parameter, grain size diameter, An empirical model which describes short and long cracks rates is developed and
is seen in good agreement with the experimental observations in this alloy. Comparison of the empirical model lives results with cumulative fatigue results has shown encouraging experimentally agreement while liner rule gave a non – reasonable prediction.