<p> Methods for modeling structural failure with applications for fluid structure interaction (FSI) are developed in this work. Fracture as structural failure is modeled in this work by both the extended finite element method (XFEM) and element deletion. Both of these methods are used in simulations coupled with fluids modeled by computational fluid dynamics (CFD). The methods presented here allow the fluid to pass through the fractured areas of the structure without any prior knowledge of where fracture will occur. Fracture modeled by XFEM is compared to an experimental result as well as a test problem for two phase coupling. The element deletion results are compared with an XFEM test problem, showing the differences and similarities between the two methods. </p><p> A new method for modeling fracture is also proposed in this work. The new method combines XFEM and element deletion to provide a robust implementation of fracture modeling. This method integrates well into legacy codes that currently have element deletion functionality. The implementation allows for application by a wide variety of users that are familiar with element deletion in current analysis tools. The combined method can also be used in conjunction with the work done on fracture coupled with fluids, discussed in this work. </p><p> Structural failure via buckling is also examined in an FSI framework. A new algorithm is produced to allow for structural subcycling during the collapse of a pipe subjected to a hydrostatic load. The responses of both the structure and the fluid are compared to a non-subcycling case to determine the accuracy of the new algorithm. </p><p> Overall this work looks at multiple forms of structural failure induced by fluids modeled by CFD. The work extends what is currently possible in FSI simulations.</p>

Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2007. / Source: Dissertation Abstracts International, Volume: 69-02, Section: B, page: 1273. Adviser: Daniel A. Tortorelli. Includes bibliographical references (leaves 84-86) Available on microfilm from Pro Quest Information and Learning.

Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2008. / Source: Dissertation Abstracts International, Volume: 69-05, Section: B, page: 3078. Adviser: John Lambros. Includes bibliographical references (leaves 163-168) Available on microfilm from Pro Quest Information and Learning.

Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2008. / Source: Dissertation Abstracts International, Volume: 69-05, Section: B, page: 3165. Adviser: Keith D. Hjelmstad. Includes bibliographical references (leaves 121-126) Available on microfilm from Pro Quest Information and Learning.

Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2007. / Source: Dissertation Abstracts International, Volume: 68-11, Section: B, page: 7614. Adviser: Robert D. Moser. Includes bibliographical references (leaves 137-140) Available on microfilm from Pro Quest Information and Learning.

Thesis (Ph. D.)--University of Illinois at Urbana-Champaign, 2007. / Source: Dissertation Abstracts International, Volume: 68-11, Section: B, page: 7516. Adviser: Keith D. Hjelmstad. Includes bibliographical references (leaves 174-182). Available on microfilm from Pro Quest Information and Learning.

Thèse (M.Sc.A.)--Université de Sherbrooke (Canada), 2008. / Titre de l'écran-titre (visionné le 1 février 2007). In ProQuest dissertations and theses. Publié aussi en version papier.

Thesis (Ph. D.)--University of Illinois at Urbana-Champaign, 2007. / Source: Dissertation Abstracts International, Volume: 69-02, Section: B, page: 1187. Adviser: Glaucio H. Paulino. Includes bibliographical references (leaves 177-186). Available on microfilm from Pro Quest Information and Learning.

Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2006. / Source: Dissertation Abstracts International, Volume: 67-11, Section: B, page: 6491. Adviser: Mark Short. Includes bibliographical references (leaves 136-143) Available on microfilm from Pro Quest Information and Learning.

<p> The present work reports on Direct Numerical Simulations of a temporally developing, zero pressure gradient, turbulent boundary along a surface piercing flat plate and its interaction with the free surface. The simulations were driven by experiments of the same flow regime. Three separate Froude numbers were considered in increasing order. Consequently the interface progresses from a rigid and undisturbed surface to one with violent eruptions, breaking waves and air entrainment. At the lowest Froude number where the surface stays flat, the simulations agreed well with prior studies and captured the recirculation regions in the cross-stream plane which are shown to be due to Reynolds stress anisotropy. At intermediate Froude numbers it was found that the main source of vorticity beneath the surface is not the Reynolds stress anisotropy but rather the vorticity generated at the interface. This vorticity was found to affect turbulent statistics including distribution of friction velocity and the slope of the log-law layer. Moreover, the present work shows that the surface generated vorticity interacts mainly with eddies of small and intermediate wave numbers and the smaller scales with high wave numbers remain intact. </p><p> Air entrainment due to turbulence was also investigated. With the aid of a prototypical problem the parameters that play a role in entrainment are established. A novel approach to quantify the turbulent structures was defined. Using this method, turbulent structures were categorized into entraining and non-entraining vortices. A Linear Logistic Regression model was trained and validated to help predict future entrainment events. The model performs well and can accurately predict entrainment events for both the turbulent regime and the prototypical problem.</p><p>