Experimental evaluation and numerical calculation of J-integral on BxB fracture toughness specimens with thickness of B=36 mm have been performed. For this thickness neither pure plane stress nor pure plane strain state assumption is not valid, because there prevails mixed state-of-stress. In that case, only solid finite element model of the specimen gives satisfied results. Unfortunately, 3-D finite element models demand much more time and efforts to obtain J-solution. Therefore, two-dimensional analyses are more user-friendly and faster, but it should be very careful by discussing of results getting into consideration all restrictions. However, it seems that for the structures with medium thickness plane strain state is more dominating, especially after initiation of the crack. But, after the onset of crack growth validity of J-dominance loses under plane strain condition. |