Experimental Determination of Apparent Fracture Toughness of Thin Aluminium Sheets

Abstract

Aluminum strips of 150mm x 50mm x 0.3mm with single edge notch depth (a) in the range of 5mm to 25mm, center crack length(2a) in range of 5m to 25mm and double edge notch specimens with individual notch depth(a) in the range of 5mm to 20mm were prepared. These strips were tested under tensile loading at a strain rate of 0.2mm/minute and 1mm/minute. The stress intensity factor (SIF) for varying notch depth was calculated using finite element simulations using global energy release rate method and domain integral (Jintegral) method. These tests were followed by preparation of strips of 150mm x 50mm x 0.3mm with inclined center crack length(2a) varying in range of 10 mm to 50mm. The angle of inclinations were 30o, 45o and 60o. These strips were tested under tensile loading at a strain rate of 0.2mm/minute. The stress intensity factor(SIF) was calculated numerically using domain integral method for the inclined crack geometries. The apparent fracture toughness(KINu) values were calculated using the peak loads obtained from the experimental data and the numerically calculated SIF’s.