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Robert H. Dodds, Jr. Professor & Civil Engineering Department Head M.T. Geoffrey Yeh Chair of Civil Engineering Former Co-Editor, Engineering Fracture Mechanics 2129 Newmark Civil Engineering Laboratory 205 North Mathews Ave. Urbana, Illinois 61801 Voice: (217) 333-3276 Fax: (217) 333-9464 rdodds@uiuc.edu |
New! Movies made from 3D elastic-plastic analyses
Research Objectives of the Group
Our research focuses on the structural engineering aspects of nonlinear fracture mechanics in ductile metals with emphasis on numerical modeling and simulation. Research achievements in this field are translated directly into safer and more economical high-performance structures, for example, welded steel frames subjected to strong earthquake motions, pressure vessels, pipelines, long-span bridges, aircraft, spacecraft and naval vessels.
Current approaches in nonlinear fatigue and fracture mechanics utilize a phenomenological description of events (material response and loading) in the vicinity of crack-like defects in structures. Results of laboratory tests on small-scale specimens are correlated, most often through large-scale numerical simulations, to the response of full-size structures. These studies address the outstanding problem of transferring measured fracture toughness data from specimens to structures.
The key to realistic correlations is a fundamental understanding of crack-tip conditions in both laboratory test specimens and actual structures for a complex array of loading (static, dynamic, tension, bending) and material behavior (brittle to fully ductile).
We develop, implement and apply micromechanical material models to describe brittle and ductile mechanisms of material separation ahead of stationary and growing crack fronts in metallic structures for both monotonic and cyclic loads. For brittle mechanisms the models incorporate a range of probabilistic treatments to quantify effects of micro-scale material variability on macroscopic fracture toughness.
Our newest work focuses on numerical modeling of low-cycle fatigue in metals used for high-performance engine components. Crack closure in complex 3-D components, cyclic plasticity models and cyclic J-integral computations form the core of this work.
Our collaborations with Prof. Paulino's group are supporting the development of new computational models for fracture in metal-ceramic functionally graded materials. This work is producing new 3-D interface-cohesive fracture models for FGMs, plasticity models for FGMs and new domain integral procedures to compute J-integral values, T-stress values and stress-intensity factors through new, novel interaction integrals.
The computational models are implemented in our advanced, 3-D nonlinear code, WARP3D. This code utilizes the most current software architecture to attain maximum performance on parallel supercomputers, high-end Unix workstations, and PC's (Windows). Conjugate gradient and sparse matrix solvers form the core algorithms with support for finite strains, fully 3-D crack growth, J-integral computation, impact loading, and automated solution logic. This code is under continuous development by our group and is freely distributed over the Internet to other fracture mechanics research groups.