Three-Dimensional Fracture Mechanics Analysis of Pit ormation Mechanism Under Lubricated Rolling-Sliding Contact Loading

Abstract In this paper, an integrity assessment of a reference Reactor Pressure Vessel (RPV) under Pressurized Thermal Shock (PTS) is performed. The assessment is based on a multi-step simulation scheme, which includes the thermo-hydraulic, thermo-mechanical and fracture mechanics analyses. The proposed strategy uses a three dimensional (3D) finite element model (FEM) of the RPV with the Abaqus code to solve the thermo-mechanical problem for the scenario of a Large-Break Loss-of-Coolant Accident (LBLOCA). In order to obtain the boundary conditions for the thermal analysis, the thermo-hydraulic results from a 3D RPV model developed in the system code TRACE are used. The fracture mechanics analysis is carried out on submodels defined on the areas of interest. Submodels containing cracks or flaws are also located in regions of the RPV where there might be a concentration of stresses during the PTS. The calculation of stress intensity factor (SIF) makes use of the eXtended FEM (XFEM) approach. The computed SIF of the postulated cracks at the inner surface of the RPV wall are compared with the ASME fracture toughness curve of the embrittled RPV material. For different transient scenarios, the boundary conditions were previously calculated with a computational fluid dynamics (CFD) model. However, cross-verification of the results has shown consistency of both CFD and TRACE models. Moreover, the use of the later is very convenient for the integrity analyses as it is clearly less computationally expensive than CFD. Therefore, it can be used to calculate different PTS scenarios including different break sizes and break locations. The main findings from fracture mechanics analyses of the RPV subjected to LBLOCA are summarized and compared. The presented results also allow us to study the influence of the dynamic cooling plume on the stress intensity factor in more detail than with the conventional one-dimensional method. However, the plumes calculated with both approaches are different. How much this difference affects the integrity assessment of the RPV is discussed in the paper.

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712 Mixed mode fracture mechanics analysis using three-dimensional virtual crack closure-integral method (VCCM) for second order tetrahedral finite element

Proceedings of the 1992 Annual Meeting of JSME/MMD ◽

10.1299/jsmezairiki.2006.0_401 ◽

2006 ◽

Vol 2006 (0) ◽

pp. 401-402

Author(s):

Hiroshi OKADA ◽

Kousuke ARAKI ◽

Hiroshi KAWAI ◽

Toshimitsu FUJISAWA ◽

Yasuyuki KANDA ◽

...

Keyword(s):

Finite Element ◽

Fracture Mechanics ◽

Crack Closure ◽

Integral Method ◽

Mixed Mode ◽

Three Dimensional ◽

Second Order ◽

Mixed Mode Fracture ◽

Mode Fracture ◽

Mechanics Analysis

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Development of the Next-Generation Computational Fracture Mechanics Simulator on the Earth Simulator 2

Volume 2: 32nd Computers and Information in Engineering Conference, Parts A and B ◽

10.1115/detc2012-70909 ◽

2012 ◽

Cited By ~ 1

Author(s):

Kaworu Yodo ◽

Hiroshi Kawai ◽

Hiroshi Okada ◽

Masao Ogino ◽

Ryuji Shioya

Keyword(s):

Finite Element Analysis ◽

Finite Element ◽

Stress Intensity ◽

Fracture Mechanics ◽

Large Scale ◽

Three Dimensional ◽

Intensity Factors ◽

Element Analysis ◽

Mechanics Analysis ◽

Analysis System

Fracture mechanics analysis using the finite element method has been one of the key methodologies to evaluate structural integrity for aging infrastructures such as aircraft, ship, power plants, etc. However, three-dimensional crack analyses for structures with highly complex three-dimensional shapes have not widely been used, because of many technical difficulties such as the lack of enough computational power. The authors have been developing a fracture mechanics analysis system that can deal with arbitrary shaped cracks in three-dimensional structures. The system consists of mesh generation software, a finite element analysis program and a fracture mechanics module. In our system, a Virtual Crack Closure-Integral Method (VCCM) for the quadratic tetrahedral finite elements is adopted to evaluate the stress intensity factors. This system can perform the three-dimensional fracture analyses. Fatigue and SCC crack propagation analyses with more than one cracks of arbitrary complicated shapes and orientations. The rate and direction of crack propagation are predicted by using appropriate formulae based on the stress intensity factors. When the fracture mechanics analysis system is applied to the complex shaped aging structures with the cracks which are modeled explicitly, the size of finite element analysis tends to be very large. Therefore, a large scale parallel structural analysis code is required. We also have been developing an open-source CAE system, ADVENTURE. It is based on the hierarchical domain decomposition method (HDDM) with the balancing domain decomposition (BDD) pre-conditioner. A general-purpose parallel structural analysis solver, ADVENTURE_Solid is one of the solver modules of the ADVENTURE system. In this paper, we combined VCCM for the tetrahedral finite element with ADVENTURE system and large-scale fracture analyses are fully automated. They are performed using the massively parallel super computer ES2 (Earth Simulator 2) which is owned and run by JAMSTEC (Japan Agency for Marine-Earth Science and Technology).

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