STP1411: Fatigue Crack Propagation under Complex Loading in Arbitrary 2D Geometries

    Miranda, ACO
    Ph.D. Student - Dept. of Civil Engineering, Research Scientist - Dept. of Mechanical Engineering, Associate Professor - Dept. of Mechanical Engineering, and Associate Professor - Dept. of Civil Engineering, Pontifical Catholic University of Rio de Janeiro (PUC-Rio), Rio de Janeiro, RJ

    Meggiolaro, MA
    Ph.D. Student - Dept. of Civil Engineering, Research Scientist - Dept. of Mechanical Engineering, Associate Professor - Dept. of Mechanical Engineering, and Associate Professor - Dept. of Civil Engineering, Pontifical Catholic University of Rio de Janeiro (PUC-Rio), Rio de Janeiro, RJ

    Castro, JTP
    Ph.D. Student - Dept. of Civil Engineering, Research Scientist - Dept. of Mechanical Engineering, Associate Professor - Dept. of Mechanical Engineering, and Associate Professor - Dept. of Civil Engineering, Pontifical Catholic University of Rio de Janeiro (PUC-Rio), Rio de Janeiro, RJ

    Martha, LF
    Ph.D. Student - Dept. of Civil Engineering, Research Scientist - Dept. of Mechanical Engineering, Associate Professor - Dept. of Mechanical Engineering, and Associate Professor - Dept. of Civil Engineering, Pontifical Catholic University of Rio de Janeiro (PUC-Rio), Rio de Janeiro, RJ

    Bittencourt, TN
    Associate Professor, Polytechnic School at the University of São Paulo (EPUSP), São Paulo, SP

    Pages: 26    Published: Jan 2002


    Abstract

    A reliable and cost effective two-phase methodology is proposed and implemented in two pieces of software to predict fatigue crack propagation in generic two-dimensional structural components under complex loading. First, the fatigue crack path and its stress intensity factor are calculated in a specialized finite-element software, using small crack increments. At each crack propagation step, the mesh is automatically redefined based on a self-adaptive strategy that takes into account the estimation of the previous step stress analysis numerical errors. Numerical methods are used to calculate the crack propagation path, based on the computation of the crack incremental direction, and the stress-intensity factors KI, from the finite element response. An application example presents a comparison between numerical simulation results and those measured in physical experiments. Then, an analytical expression is adjusted to the calculated KI(a) values, where a is the length along the crack path. This KI(a) expression is used as an input to a powerful general purpose fatigue design software based in the local approach, developed to predict both initiation and propagation fatigue lives under complex loading by all classical design methods, including the S-N, the ε-N and the IIW (for welded structures) to deal with crack initiation, and the da/dN to treat propagation problems. In particular, its crack propagation module accepts any KI expression and any da/dN rule, using a ΔKrms or a cycle-by-cycle propagation method to deal with one and two-dimensional crack propagation under complex loading. If requested, this latter method may include overload-induced crack retardation effects.

    Keywords:

    fatigue crack propagation, finite elements, arbitrary loading


    Paper ID: STP10608S

    Committee/Subcommittee: E08.93

    DOI: 10.1520/STP10608S


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