IWPDF2023

Parametrically-Upscaled Constitutive Model (PUCM) and Crack Nu cleation Model (PUCNM) for Fatigue Predictions in Ti Alloys

S. Ghosh ∗ , S. Kotha, D. Ozturk, G. Weber

Department of Civil & Systems Engineering, Mechanical Engineering and Materials Science & Engineering, Johns Hopkins University, Baltimore, Maryland, USA

∗ sghosh20@jhu.edu

Keywords: Parametric Upscaling, RAMPS, Fatigue Crack Nucleation

This talk will give an overview of the Parametrically Upscaled Constitutive Model (PUCM) and Parametrically Upscaled Crack Nucleation Model (PUCNM) for Ti alloys [1-6], whose polycrys talline microstructures include micro-texture regions (MTRs). The micromechanics-informed PUCMs differ from conventional phenomenological models in their unambiguous depiction of constitutive parameters and their dependencies. The PUCMs are thermodynamically consis tent, macroscopic constitutive models, whose coefficients are explicit functions of Representa tive Aggregated Microstructural Parameters (RAMPs), representing statistical distributions of morphological and crystallographic descriptors of the microstructure, e.g., texture and grain size distributions. The microstructure-dependent constitutive parameter functions are effective for es tablishing connections between microstructure and relevant higher-scale material response. They enable computationally efficient simulations with significant speedup over detailed lower-scale models and conventional multi-scale models. Development of the PUCMs requires a compre hensive framework, involving material characterization, micromechanical analysis using calibrated models, identification of characteristic forms of constitutive relations, sensitivity analysis, compu tational homogenization, machine learning and validation with experimental data. Furthermore, the upscaling platform is coupled with uncertainty quantification (UQ) and propagation. The PUCM/PUCNM tool is used to predict deformation and fatigue crack nucleation in aerospace structures under monotonic and cyclic loading conditions. References [1] S. Kotha, D. Ozturk, and S. Ghosh. Parametrically homogenized constitutive models (PHCMs) from micromechanical crystal plasticity FE simulations, part I: Sensitivity analysis and parameter identification for titanium alloys. Int. J. Plast., 120:296–319, 2019. [2] S. Kotha, D. Ozturk, and S. Ghosh. Parametrically homogenized constitutive models (PHCMs) from micromechanical crystal plasticity FE simulations: Part II: Thermo-elasto-plastic model with experimental validation for titanium alloys. Int. J. Plast., 120:320–339, 2019. [3] S. Kotha, D. Ozturk, and S. Ghosh. Uncertainty-quantified parametrically homogenized consti tutive models (UQ-PHCMs) for dual-phase α / β titanium alloys. npj Comput. Mater., 6(1):1–20, 2020. [4] D. Ozturk, S. Kotha, and S. Ghosh. An uncertainty quantification framework for multi scale parametrically homogenized constitutive models (PHCMs) of polycrystalline Ti alloys. Jour. Mech. Phys. Solids, 148:104294, 2021. [5] J. Shen, S. Kotha, R. Noraas, V. Venkatesh, and S. Ghosh. Developing parametrically up

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