A hierarchical multi-physics model for design of high toughness steels

Su Hao*, Brian Moran, Wing Kam Liu, Gregory B. Olson

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

68 Scopus citations


In support of the computational design of high toughness steels as hierarchically structured materials, a multiscale, multiphysics methodology is developed for a 'ductile fracture simulator.' At the nanometer scale, the method unites continuum mechanics with quantum physics, using first-principles calculations to predict the force-distance laws for interfacial separation with both normal and plastic sliding components. The predicted adhesion behavior is applied to the description of interfacial decohesion for both micron-scale primary inclusions governing primary void formation and submicron-scale secondary particles governing microvoid-based shear localization that accelerates primary void coalescence. Fine scale deformation is described by a 'Particle Dynamics' method that extends the framework of molecular dynamics to multi-atom aggregates. This is combined with other meshfree and finite-element methods in two-level cell modeling to provide a hierarchical constitutive model for crack advance, combining conventional plasticity, microstructural damage, strain gradient effects and transformation plasticity from dispersed metastable austenite. Detailed results of a parallel experimental study of a commercial steel are used to calibrate the model at multiple scales. An initial application provides a Toughness-Strength-Adhesion diagram defining the relation among alloy strength, inclusion adhesion energy and fracture toughness as an aid to microstructural design. The analysis of this paper introduces an approach of creative steel design that can be stated as the exploration of the effective connections among the five key-components: elements selection, process design, micro/nanostructure optimization, desirable properties and industrial performance by virtue of innovations and inventions.

Original languageEnglish (US)
Pages (from-to)99-142
Number of pages44
JournalJournal of Computer-Aided Materials Design
Issue number2
StatePublished - 2003
Externally publishedYes

Bibliographical note

Funding Information:
The steel design project is funded by ONR Grant Number: N00014-01-1-0953). The support of ONR is greatly appreciated. The authors are grateful to the Caterpillar Technical Center for providing data on the modified 4340 steel. Su Hao thanks Dr. Singh of NRL for providing the DOD Plane Wave Code and Dr. Mehl of NRL for providing the NRL Tight-Binding Code. Su Hao is also grateful for discussions with Prof. Freeman of Northwestern University.

ASJC Scopus subject areas

  • General Materials Science
  • Computer Science Applications
  • Computational Theory and Mathematics


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