Issue 38

F. Majid et alii, Frattura ed Integrità Strutturale, 38 (2016) 273-280; DOI: 10.3221/IGF-ESIS.38.37 277 In this perspective, simplifying the testing procedures is required by opting for static tests instead of dynamic tests which are so expensive and difficult. The unified theory developed by Bui Quoc in 1971, has the advantage of ensuring an assessment of the damage through dynamic and static tests. In this paper we evaluated the damage through a combined theory using the unified theory [48,49] and burst pressure Eq. (16) and (17). ur u s a u P P D P P 1 1    (18) where P ur is the burst pressure for notched cylinder, P u is the burst pressure for a unotched cylinder and P a is the pressure before rupture. The approach presented in this part of the paper is based on artificial damage creation by creating a notch with a variable depth and then we evaluate the damage for each depth. The cylinder we are working on has a thickness of 5.8 mm, an external diameter of 63 mm and a length of 400 mm. The operating pressure for the case study is 0.6 MPa. The mechanical properties of the studied material are given in the Tab. 3 obtained from mechanical characterization we did through tensile tests. (a) (b) Figure 2 : Notched cylinder (a) FEA of notched cylinder (b) . Material Yield stress σ y (MPa) Ultimate stress σ u (MPa) P265GH 320 470 A36 372 621 Table 3 : Mechanical properties of materials. In this part of the paper, we proved that a combination between the unified theory and the burst pressure formulas is possible. Then we showed that we can predict the fracture by theoretical calculations. We proved also that the unified theory can be used with burst pressure formulas based on combined applied axial stress and internal pressure. The burst pressure is decreasing while the notch depth increases. Meanwhile, the cumulative based on the burst pressure formulas is almost the same as the one obtained by experimental tests and the use of the unified theory. C ONCLUSION ressure vessel design pass through many steps as shown in this article. The minimum requirement according the ASME code has been resumed in the first part of the article. Then, a review and a discussion of pressure vessels fatigue design have been detailed. In the third part of the article, we discussed the multiaxial fracture by giving an overview of almost the methods and formulas of burst or rupture pressure. The limit pressure is determined through the P