Fatigue in Materials: Fundamentals, Multiscale Characterizations and Computational Modeling: Multiscale Modeling Approaches to Improve Fatigue Predictions I
Sponsored by: TMS Materials Processing and Manufacturing Division, TMS Structural Materials Division, TMS: Mechanical Behavior of Materials Committee, TMS: Computational Materials Science and Engineering Committee, TMS: Integrated Computational Materials Engineering Committee, TMS: Advanced Characterization, Testing, and Simulation Committee, TMS: Additive Manufacturing Committee
Program Organizers: J.C. Stinville, University of Illinois Urbana-Champaign; Garrett Pataky, Clemson University; Ashley Spear, University of Utah; Antonios Kontsos, Drexel University; Brian Wisner, Ohio University; Orion Kafka, National Institute Of Standards And Technology
Wednesday 2:00 PM
March 22, 2023
Room: Sapphire H
Location: Hilton
Session Chair: Antonios Kontsos, Drexel University
2:00 PM
PRISMS-Fatigue Framework: Effects of Sample Size, Grain Neighborhood, and Surface Roughness on Extreme Value Fatigue Response: Mohammadreza Yaghoobi1; Krzysztof S. Stopka2; John E. Allison1; David McDowell3; 1University of Michigan; 2Purdue University; 3Georgia Institute of Technology
PRISMS-Fatigue is a novel open-source framework that enables simulation-based comparisons of microstructures with regard to fatigue resistance for polycrystalline metals and alloys. The framework uses the crystal plasticity finite element software PRISMS-Plasticity as its microstructural analysis tool. PRISMS-Fatigue is incorporated to investigate the effect of sample length scale, grain neighborhood, and surface roughness on the extreme value fatigue response. An increase in the intensity of realistic surface roughness profiles corresponds accordingly to larger FIPs but it is difficult to precisely interpret the mechanisms and effects of this intensification. We thus parametrically investigate surface asperities that couple with microstructure and lack of constraint on slip at the free surface to describe microstructure-sensitive surface roughness knockdown effects on fatigue resistance. The depth of a single valley (i.e., notch) due to surface roughness is found to be more detrimental to fatigue resistance than the radius.
2:20 PM
Modeling Fatigue Resistance in Additively Manufactured Alloys with Porosity Defects: Krzysztof Stopka1; Michael Sangid1; 1Purdue University
Widespread adoption of additively manufactured (AM) components is hindered due to porosity defects that often govern minimum fatigue life. Computational models can offer insight into failure mechanisms beyond the capabilities of experimental characterization. In this work, crystal plasticity simulations are employed to compute the micromechanical response of Ni-base superalloy IN718 in the low cycle fatigue regime. Digital microstructure models with realistic defects are instantiated using electron backscatter diffraction and computed tomography scans of AM builds intentionally seeded with different defect structures. The critical accumulated plastic strain energy density, a metric related to the material’s intrinsic resistance to fatigue crack initiation, is computed using an uncertainty quantification Bayesian inference framework with model results and fatigue lives from an experimental campaign. The discussion will highlight techniques for integrating experimental and model data to statistically quantify the debit in fatigue resistance due to distinct defect structures.
2:40 PM
Integrated Computational Modeling to Link Process with Fatigue Behavior for Metal Additive Manufacturing: Mehdi Amiri; Katerine Saleme1; Maria Emelianenko2; Bernhard Peters1; 1The University of Luxembourg; 2George Mason University
We present a computational framework for studying the process-defect-life prediction of additive manufactured metals using a suite of computational models. The laser powder bed fusion (LPBF, process parameters including (laser power, scan speed, etc) are modeled using a novel extended discrete element method (XDEM), which predicts the thermodynamic state and phase change for each powder grain. The surrounding continuous gas and liquid phases are solved with multi-phase computational fluid dynamics (CFD) to determine momentum, heat, gas and liquid transfer. The thermal history obtained in the previous simulations are used to predict microstructure formation through coupling the SPPARKS Kinetic Monte Carlo Simulator. The predicted porosity and microstructure are further used in DREAM.3D to generate synthesized representative volume element (RVE) with embedded porosity. A crystal plasticity finite element (CPFEM) model is used to predict Fatigue Indicator Parameters (FIPs) which capture the driving force responsible for fatigue crack formation.
3:00 PM
Molecular Dynamics Simulations of the Thermal Evolution of Voids in Cu Bulk and Grain Boundaries: Vasileios Fotopoulos1; Alexander Shluger1; Ricardo Grau-Crespo2; Corey O'Hern3; 1University College London (UCL); 2University of Reading; 3Yale University
In this work, we combined Density Functional Theory (DFT) with Bond Order potentials (BOP) Molecular Dynamics (MD) simulations to examine the effect of hydrogen in the properties of the polycrystalline Cu. Our tensile strain MD simulations showed that grain boundaries (GBs) and triple junctions aggregate high stresses which they release via the emission of twin dislocations. Dislocation analysis showed that the presence of H facilitates the formation of Shockley dislocations close to the GBs. Delaunay tessellation analysis showed that H and Cu vacancies complexes in Σ5 GBs withstand temperatures up to 700 K without dissociating, with H having a stabilization effect in the vacancies in GBs during thermal annealing. DFT showed that the presence of H interstitials significantly decreases the formation energies of mono, di-vacancies and tri-vacancies. Thus, H presence in the GBs is expected to increase locally the concentration of vacancies and facilitate the growth of larger vacancy clusters.
3:20 PM Break
3:35 PM
Grain Scale Deformation Study of a Nickel-based Superalloy under Thermo-mechanical Fatigue Utilizing Crystal Plasticity Simulations and High-energy X-ray Diffraction Microscopy: Brandon Mackey1; Ritwik Bandyopadhyay1; Sven Gustafson1; Michael Sangid1; 1Purdue University
Nickel-based superalloys are used for applications in the hot sections of gas turbines because of their high strength at elevated temperatures. These materials are subjected to complex thermo-mechanical loading due to service conditions which leads to thermo-mechanical fatigue (TMF) failure. The failure mechanisms associated with TMF are dependent on microstructural characteristics and parameters such as temperature, strain range, and strain-temperature phasing. Using microstructural information reconstructed from a high-energy X-ray diffraction microscopy (HEDM) TMF experiment, we generate a temperature-dependent crystal plasticity model for LSHR, a Nickel-based superalloy, to study failure mechanisms associated with TMF. Crystal plasticity predicted damage locations are determined and connected to HEDM grain scale metrics such as slip system activity, spot spreading, and grain neighbor interactions to understand physical mechanisms influencing TMF damage.
3:55 PM
Crystal-Plasticity Modeling of Monotonic and Cyclic Softening in Inconel 718 Superalloy: Jean-Briac le Graverend1; 1Texas A&M University
A phenomenological model is proposed to predict both monotonic and cyclic softening in Inconel 718 superalloy at 650°C. The developed internal state variable is implemented in a crystal-plasticity model and is tested on uniaxial strain-controlled monotonic and cyclic loading as well as on uniaxial stress-controlled cyclic loading. The simulation results qualitatively and quantitatively predict strain-controlled monotonic softening/hardening responses depending on the strain rate as well as strain-controlled and stress-controlled cyclic softening/hardening as a function of the strain rate, the stress and strain amplitudes, and the mean stress. Furthermore, the prediction of ratcheting (rate and magnitude) is consistent with experimental results.
4:15 PM
Investigation of Irreversible Slip and Intragranular Lattice Rotations in Polycrystalline Inconel 718 during Cyclic Loading: Justine Schulte1; Jonathan Hestroffer1; Dalton Shadle2; Kelly Nygren3; Matthew Miller2; Tresa Pollock1; Irene Beyerlein1; 1University of California, Santa Barbara; 2Cornell University; 3Cornell High Energy Synchrotron Source
Fatigue is a life-limiting property for many structural aircraft engine materials. To design better alloys for this application, it is necessary to understand the slip behavior that precedes crack initiation on a sub-grain level. Intragranular lattice rotation gradients can serve as an indicator of slip activity and, in cyclic loading, the connection between the irreversibility of these gradients and irreversible slip can be examined. In this study, 3D crystal plasticity finite element (CPFE) modelling is coupled with in-situ high energy x-ray diffraction microscopy (HEDM) data to link intragranular lattice rotation gradients with slip processes within polycrystalline Inconel 718 during cyclic loading. These complementary techniques provide information on the spatially resolved lattice rotation gradients, slip activity, stress and strain states within the microstructure. The links between these quantities can ultimately determine which intragranular rotation gradients are irreversible, and thus identify potential sites for crack initiation and their dependence on microstructural features.
4:35 PM
A Novel Multiaxial Strain-Life Approach for Nickel-base Superalloys: Firat Irmak1; Ali Gordon1; 1University of Central Florida
Nickel-base superalloys (NBSAs) are a group of materials that are extensively used in high-temperature applications such as aero and industrial gas turbine applications. These alloys can endure high temperatures and stresses for extended periods, they also exhibit excellent fatigue life and corrosion-resistant properties. Multiaxial states of stress and strain are very common in engineered parts. Components such as crankshafts, pressure vessels, welded joints, heavy construction equipment, and the like experience external loads in multiple axes. Multiaxial approaches have been introduced to give improved predictions of fatigue life under complex states compared to what can be attained with uniaxial methods alone. A novel multiaxial strain-based life approach is developed in this study. A yield criterion, developed by the authors, is utilized to obtain effective strain values and to capture multiaxial state of strain. This approach is exercised and compared with experimental data from various single crystal (SX) NBSAs.
4:55 PM Cancelled
Phase-field Modeling of Fatigue Microstructures in Ni-based Single Crystal Superalloys: Jose Dominic1; Jean-Briac le Graverend1; 1Texas A&M University
NI-based Single-crystal superalloys are also subjected to fatigue loading that has a significant effect on the microstructure evolution and the rafting process in particular. It has been experimentally observed that rafting will occur at 45° when an alternate low cycle fatigue loading is applied. It is well known that the microstructural state has a large effect on mechanical performance during creep and fatigue. Phase-field simulations are performed with an anisotropic apparent diffusion coefficient that allows to predict tilted rafts during alternate fatigue loading at high temperature which will be used to create a map of fatigue conditions for which raft tilting occurs.
5:15 PM
Framework to Model Single crystal and Directionally Solidified Nickel Base Superalloys under a Wide Range of Monotonic, Cyclic, Thermomechanical Fatigue and Creep Fatigue Conditions: Navindra Wijeyeratne1; Ali Gordon1; 1University of Central Florida
Nickel base superalloys (NBSAs) are a type of material that is primarily utilized in high-temperature applications due to their superior material properties at elevated temperatures. Single crystal (SX) and directionally solidified (DS) are widely utilized to develop components such as gas turbine blades. During the development, phase is essential to understand the behavior of the material under certain loading conditions. Thus, developing a framework that combines experimental data with theoretical mechanics and numerical simulations is vital. In NBSAs plasticity is induced at the slip system level. Crystal viscoplasticity (CVP) theory models the effects of crystallographic slip to provide a more accurate description of the effects of plasticity, enabling it to capture these materials' orientation rate, temperature, and history-dependence under a variety of conditions. A complete framework utilizing CVP theory and a novel optimization scheme is developed to model the thermomechanical fatigue and creep-fatigue behavior of any SX and DS NBSAs.