Crack nucleation at forging flaws studied by non-local peridynamics simulations
[1];
[5];
[6];
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, USA
- Siemens Energy, Inc., Charlotte, USA
- Siemens Corporation, Technology Division, Charlotte, USA
- Siemens Energy Global GmbH & Co. KG, Mülheim a.d.R., Germany
- Department of Civil and Environmental Engineering, Carnegie Mellon University, USA
- Sandia National Laboratories, Albuquerque, USA
In this study, we present a computational study and framework that allows us to study and understand the crack nucleation process from forging flaws. Forging flaws may be present in large steel rotor components commonly used for rotating power generation equipment including gas turbines, electrical generators, and steam turbines. The service life of these components is often limited by crack nucleation and subsequent growth from such forging flaws, which frequently exhibit themselves as non-metallic oxide inclusions. The fatigue crack growth process can be described by established engineering fracture mechanics methods. However, the initial crack nucleation process from a forging flaw is challenging for traditional engineering methods to quantify as it depends on the details of the flaw, including flaw morphology. We adopt the peridynamics method to describe and study this crack nucleation process. For a specific industrial gas turbine rotor steel, we present how we integrate and fit commonly known base material property data such as elastic properties, yield strength, and S-N curves, as well as fatigue crack growth data into a peridynamic model. The obtained model is then utilized in a series of high-performance two-dimensional peridynamic simulations to study the crack nucleation process from forging flaws for ambient and elevated temperatures in a rectangular simulation cell specimen. The simulations reveal an initial local nucleation at multiple small oxide inclusions followed by micro-crack propagation, arrest, coalescence, and eventual emergence of a dominant micro-crack that governs the crack nucleation process. The dependence on temperature and density of oxide inclusions of both the details of the microscopic processes and cycles to crack nucleation is also observed. Finally, the results are compared with fatigue experiments performed with specimens containing forging flaws of the same rotor steel.
- Research Organization:
- Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
- Sponsoring Organization:
- USDOE National Nuclear Security Administration (NNSA); Los Alamos National Laboratory (LANL); US Department of the Navy, Office of Naval Research (ONR); US Army Research Office (ARO)
- Grant/Contract Number:
- 89233218CNA000001; NA0003525; N00014-18-1-2528; MURIW911NF-19-1-0245
- OSTI ID:
- 1835949
- Alternate ID(s):
- OSTI ID: 1882874
- Report Number(s):
- SAND2022-0054J
- Journal Information:
- Mathematics and Mechanics of Solids, Journal Name: Mathematics and Mechanics of Solids Vol. 27 Journal Issue: 6; ISSN 1081-2865
- Publisher:
- SAGE PublicationsCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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