Project abstract for group fokalex

Numerical Analysis of Structures

Excessively high stresses at the interface between biological tissues and dental restorations are thought to be the main cause of restoration failure such as deterioration at the restoration margins, fracture of restoration, and bone resorption around dental implants. The aim of the first project by this group is to increase the reliability and longevity of dental restorations by reducing the interfacial stresses through modern shape and material optimization techniques. Optimization methods that mimic biological growth will be coded as user-material subroutines in the commercial finite element code Abaqus. The program together with the subroutines will be used to optimize the shapes and material distributions of dental restorations that range from cavity preparations to fiber-reinforced dental bridges and dental implants. Prior to this, anatomically realistic models will be created using images obtained from a micro-CT scanner. Commercial software such as Mimics will be used for such purposes. The results from the finite element studies will then provide guidelines for the formulation of appropriate laboratory tests to validate the optimization approach. Abaqus, together with a user-element subroutine based on continuum damage mechanics, is also being used to simulate the debonding and fracture of dental restorations. This helps to minimize the costs of experimental validation by evaluating the likelihood of success of the optimized designs numerically beforehand.

A second project aims to address the key research need for the development of constitutive models and overall failure models for graphite and high temperature structural materials, with the long-term goal being to maximize the design life of the Next Generation Nuclear Plant (NGNP). To this end, the capability of a Continuum Damage Mechanics (CDM) model, which has been used successfully for modeling fracture of virgin graphite, will be extended as a predictive and design tool for the core components of the Very High Temperature Reactor (VHTR). Irradiation and environmental effects pertinent to the VHTR will be incorporated into the model to allow fracture of graphite and ceramic components under in-reactor conditions to be modeled explicitly using the commercial finite element software Abaqus. To reduce the arbitrariness and uncertainties associated with the current statistical approach, Monte Carlo analysis will be performed to address inherent variations in material properties.

A bibliography of this group’s publications acknowledging MSI is attached.