Issue 38

F. Majid et alii, Frattura ed Integrità Strutturale, 38 (2016) 273-280; DOI: 10.3221/IGF-ESIS.38.37 276 M ULTIAXIAL FRACTURE OF THICK WALL CYLINDER he wall of the pressure cylinders generally undergoes triaxial loading Axial, circumferential and radial. In fact, many theories have been developed to predict the fracture of pressure cylinder by determining the limit charges. There are some theories which are dealing only with the internal pressure. Other theories are focusing on the applied axial stress. And the last category is dealing with both of them. In the table below, we present a review of almost all the theories dealing with the limit internal pressure and the combined internal pressure and applied axial stress. For the first category, they are predicting the rupture pressure. Meanwhile, the second category they are fixing either the internal pressure or the applied axial stress and predicting the other one. Theories Author,year Equation Internal pressure Hill, 1950 [41]. y i D P D 0 2 ln 3         (10) Nadai, 1950 [42]. UTS i D P D 0 2 ln 3         (11) Faupel, 1956 [43]. y y UTS i D P D 0 2 2 ln 3                 (12) Asser Brabin, 2009 [44]. y y UTS i D P D 0 2 (1 1 ln 3                              (13) DNV,2010 [45]. y m t P D 2 2 3   (14) KleverFJ, 2006 [46]. Stewart G, 1994 [47].   UTS n n m t P D 1 1 2 1 2 2 3                (15) Combined internal pressure and axial applied stress Klever FJ, 2006 [46]. Stewart G, 1994[47].   n n n i eff UTS UTS m P t D 1 1 1 3 1 4 3 2 4                      (16)   i m n n UTS n n UTS P D t P 2 1 1 1 1 2 4 3 4 1 3 3                    (17) Table 2 : Overview of multiaxial fracture in the limit conditions. C UMULATIVE DAMAGE EVALUATION BY A THEORY COMBINATION he prediction of intervention’s time by the maintenance services is generally very difficult unless we figure out when the damage could occur. In fact, determining the damage, In the ASME code, is generally evaluated through linear methods like MINER, although the results obtained by this method are very approximate. However, the non-linear quantifications of the damage seem difficult due to the big number of parameter. T T