Experimental determination of apparent fracture toughness of aluminium sheet for varying strain rate

Abstract

Preparation of aluminum samples with dimensions as 250mm (50mm grip length on each side)×50mm×0.3mm with different cracked geometry like single edge notch, double edge notch, centered cracked, inclined crack at an angle 30°, 45° and 60°.
Each sample will have three specimens, keeping the geometry of the samples as constant and by increasing the length of the crack, as for the case of single edge notch the crack length (a) is varied from 5mm,10mm,15mm,20mm,25mm. Similarly, for double edge notch the crack length (2a) is varied from 10mm, 20mm, 30mm, 40mm. For centered crack sample crack length(a) is varied from 5mm,10mm,15mm,20mm,25mm. For inclined crack at an angle 30°, 45°,60° the crack length (2a) is varied from 10mm,20mm,30mm,40mm,50mm, so a total number of 29 samples are prepared. After the preparation of the samples each sample is tested in tensile testing machine and the stress at maximum load is calculated for each sample.
For single edge notch, double edge notch, centered crack specimens the tensile test is done for 0.2mm/min strain rate and 1mm/min strain rate. For inclined crack sample tensile test was done for 0.2mm/min strain rate only.
Modelling of the above samples geometry and then calculating the value of stress intensity factor numerically using global energy compliance method and J‐integral method. Obtaining the apparent fracture toughness from stress intensity factor and stress at maximum load for each sample.