Civil Engineering

 

Date of this Version

Summer 6-2011

Comments

A DISSERTATION Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfillment of Requirements For the Degree of Doctor of Philosophy, Major: Engineering (Civil Engineering), Under the Supervision of Professor Yong-Rak Kim. Lincoln, Nebraska: June, 2011

Copyright 2011 Jamilla Emi Sudo Lutif

Abstract

This study presents a multiscale computational model with its verification and validation to mechanical behavior predictions of bituminous composites that are subject to fracture damage. Bituminous composites are classical examples of multi-phase composites in different length scales. The understanding of the mechanical behavior of asphaltic media has been a challenge to the pavement mechanics community due to multiple complexities involved: heterogeneity, anisotropy, nonlinear inelasticity, and damage growth in multiple forms. To account for this problem in an accurate and efficient way, this study proposes the use of the two-way coupled multiscale computational modeling technique.

The two-way coupled multiscale model is based on continuum thermo-mechanics and is implemented using a finite element formulation. Two length scales (global and local) are two-way coupled in the model framework by linking a homogenized global scale to a heterogeneous local scale representative volume element (RVE). With the unique multiscaling and the use of the finite element technique, it is possible to take into account the effect of material heterogeneity, inelasticity, and anisotropic damage accumulation in the small scale on the overall performance of larger scale structures.

Along with the theoretical model formulation, several example problems are shown: some to verify the model and its benefits through comparisons with analytical solutions and single-scale simulation results, and others to validate the applicability of the approach to model bituminous composite where material viscoelasticity, mixture heterogeneity, and cohesive zone fracture are involved.

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