A Moving-Grid Finite Element Method for

            Modeling Transient Crack Growth in Creeping Materials

 

Lee, Hae Sung

 

ABSTRACT

 Many metals exhibit creep behavior at temperatures greater than about 30% of their absolute melting point. Creep behavior governs crack growth in some structures that are exposed to high temperatures throughout their service life, such as nuclear power plants and gas turbines This paper presents a moving-grid finite element method for the analysis of transient crack growth in creeping materials. The proposed method is based on the mixed Eulerian-Lagrangian kinetic description (ELD), which can simulate continuous crack-tip motion by a time-dependent mapping. Since the constitutive equation for a history-dependent material becomes a first-order differential equation in the ELD, a mixed variational principle in which the displacement and the creep strain appear as independent variables is developed. The discontinuous Galerkin method is employed to stabilize the first-order hyperbolic differential equation and the mixed formulation. New results obtained by the proposed methods are presented for transient, mode- crack growth in creeping materials.

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