Yorulma İşlemi Sırasında Başlatılmış Lineer Çatlak İlerlemesinin, Değişik Kalınlıktaki ve Yüksek Gerilme Oranlarındaki Al - Zn - Mg - Cu (7075-T6) Alüminyum Alaşımından İmal Edilmiş CT (Compact Tension) Numuneleri Üzerinde, Tetkiki

Abstract

Tensile and Fatigue Crack Propagation (FCP) test have been carried out on specimens of 7075 - T6 Aluminium alloy of two ranges of thicknesses which are 10 mm. and 24 mm. Rates of fatigue crack propagation vs. range of stress intensity factor (Al<) curves for this alloy has been plotted. Axial - loads were used on 120 mm. wide CT (Compact Tension) specimens. These tests were made at different stress ratios R (ratio of the minimum stress to the maximum stress) ranging from 0.6 to 0.911 and at maximam stress levels ranging from 0.6 - 2.7 Ksi (4.1- 18.4 MN/nr2) to study the effects of stress ratio on fatigue crack growth. The results were compared for both thicknesses. Finally, the da/dN versus K data have been analysed and «best fit» straight lines for the graphs computed by the least square method.