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On Better Understanding Dilute Void Growth in Ductile Metals

  • Author(s): Kostka, Tim
  • Advisor(s): Zohdi, Tarek I
  • et al.
Abstract

In this dissertation, we examine the problem of dilute void growth in ductile metals, where a single void is growing in an infinite matrix and subject to a far field macroscopic stress. We look at varying elements of the far field loading condition (e.g. triaxiality, prolateness), at varying the void parameters (e.g. initial shape), and at varying the isotropic hardening model. We perform simulations first with a linearly hardening model, and later with a power law hardening model, which is closer to the models used in classical papers.

We then look at two voids in close proximity to one another but still subject to the far field stress. In this problem, we vary the void spacing, loading direction, and hardening model.

A finite element software in C++ has been authored to run these simulations. The element formulation for results shown in these include a 20 noded hexahedron element integrated with a 14 point, 5th order rule. An introduction to the finite element method, along with details of the elements, integration schemes, linear and non-linear solvers, and boundary conditions are also provided.

Finally, we compare results obtained from this analysis to classical void growth models to show similarities and differences. While nearly all models discussed agree to within an order of magnitude, significant differences are found at higher triaxialities (where void growth is especially important).

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