This paper describes numerical analyses performed in connection with the design of a large scale mock-up test planned within the European project on structural integrity STYLE. There are three large scale mock-up tests planned in STYLE, each of them dedicated to investigate specific effects. Mock-up3 (cladded ferritic pipe with an outer diameter of 420 mm) is foreseen to investigate transferability of material data, including fracture mechanics properties. Usually, material data are obtained by testing small specimens, which are subsequently used for the assessment of large scale structures (real components). The Mock-Up3 is an original part of a surge line made of low alloy steel 20MnMoNi55 (similar to SA 508 Grade 3, Cl. 1). The test will be performed on a 4 point bending test facility provided by EDF under displacement control at room temperature. The goal of the test is to obtain the stable crack growth of an inner surface flaw until a break through the wall occurs. The range of assessment tools applied within STYLE includes assessment of component failure by fracture mechanics analyses using methods based on fracture mechanics parameters (e.g K1 or J-Integral) as well as methods based on local micromechanical models (e.g. Gurson’s porous plasticity model and its variations). Micromechanical models have some advantages compared to those based on single term fracture parameters, especially if one considers designing a large scale mock-up test. The precise description of the entire damage process, beginning from with initiation on brittle particles, their growth leading to the crack initiation and finally to the macroscopic crack growth, can be seen as the most valuable attribute of these methods. Such methods make it possible to perform a set virtual tests prior to the real one, on which different test conditions can be investigated. A comparison of the common assessment method based on J-Integral with a local approach method, based on the Gurson’s porous plasticity theory, will be presented in this paper. Details on the Gurson model calibration will also be provided. Moreover, influence of boundary conditions on the large scale test will be discussed.

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