Computational Mechanics Research Laboratory

Computational Modeling System for Deformation and Failure in Polycrystalline Metals

Sponsor: Air Force Office of Scientific Research

 

PI: S. Ghosh

 

Keywords: Crystal Plasticity Simulations, Microstructure Design

 

Abstract:

The proposed research will develop an integrated system of experimentally validated computational models, for simulating the deformation and failure behavior of polycrystalline metals and alloys. The system will consist of computational models and software for: (a) 3D microstructure reconstruction and characterization of morphological and crystallographic information, (b) image-based microstructural computational models incorporating crystal plasticity and fracture laws, and (c) a multi-time scaling time integration algorithms for cyclic deformation, to investigate the effect of material microstructure on deformation behavior and fatigue life. The computational system is expected to assist engineers, especially in the aircraft engine industry, in their product design for enhanced performance and reliability.

Computational models will be developed in the proposed program to incorporate accurate microstructural morphology and crystallographic information for analyzing structure-sensitive deformation and fatigue behavior. Primary focus will be on aerospace metals and alloys, e.g. IN-100, Ti-6242 and Ti-6Al-4V, with a motivation to improve performance and reliability of aerospace engine materials. A comprehensive approach will be pursued, coupling the following elements:
(i) Reconstruction of 2D and 3D microstructural models with real morphological features and crystallographic orientations from quantitative metallography combining focused ion beam (FIB) and electron back-scatter detector (EBSD) in orientation imaging microscopy, microstructural characterization, and statistical methods.
(ii) Development of experimentally validated finite deformation rate-dependent crystal plasticity models with size effects, for analyzing deformation and creep in polycrystalline aggregates.
(iii) Development of an experimentally validated cohesive zone model for inter and intra-granular fracture initiation and growth for fatigue crack modeling.
(iv) Development of a stable, accurate and efficient image-based micromechanical finite element model, for crystal plasticity and damage, incorporating real morphological and crystallographic features. A novelty of this model would be in the powerful adaptive techniques for automatically changing the element resolution and topology with evolving strain localization and damage.
(v) Development of multi-scaling algorithms in the time domain for compression and localization in cyclic deformation analysis.

In summary, the proposed research will develop experimentally validated innovative high fidelity computational tools to provide improved predictive capabilities for fatigue failure analysis in materials with aerospace applications. The program is expected to advance the state of the art in analysis methodology for high confidence in component performance and life calculations.

 

OSU Research Team

Professor: S. Ghosh,
Graduate Students: Gayathri Venkatramani, Yash Bhandari

External Research Team

Dr. D. Dimiduk, Dr. M. Uchic and Dr. T.A. Parthasarathy of AFRL/MLLM,

 

Research Partners

Air Force Research Laboratory
Prof. M. Mills, Prof. H. Fraser