FEA of jaw and implant

The main focus of our research is in applied mechanics with particular emphasis on:

  • Mechanics and tribology of flexible webs/tapes
  • Particle based surface engineering methods
  • Biomechanics of dental implants


Mechanics and Tribology of Flexible, Translating Webs/Tapes

Thin continuous, flexible materials used in manufacturing a wide range of products ranging from paper to flexible computer displays, and in information storage such as magnetic tape, are known as webs . In a typical web handling application a continuous sheet of material moves beetween a supply and take-up roll, over and under rollers, air flotation guides, dryers, printer/recording heads, nozzles. In many of these applications accurate placement of the web near the printer/recorder heads and nozzles is critical. Moreover, it is crucial to confine the lateral motion of the web to a predetermined path.

These requirements may be difficult to meet due to a variety of effects such as the imperfections in the web material, web-path, fluid-structure interactions between the web and the surrounding fluid (air). This field brings two diverse areas of mechanics, namely dynamics and tribology, together. Our work in this field has been focused on the following areas:

  • Fluid-structure interactions in web handling
    • Magnetic read/write head contours
    • Roller traction
    • Externally pressurized air-guides
  • Dynamics of translating media
    • Out-of-plane and lateral dynamics of translating webs/tapes
    • Dynamic interactions of a translating web with a lubricating air layer over a guide


Biomechanics

Our groupsís primary focus in bioengineering has been to introduce rigorous mechanics based analysis of the biomechanical factors that affect the long term success of dental implant treatments.

  • Bone remodeling around an implant: Our analysis of on bone remodeling around a dental implant system was the first to show the significance of large scale surface textures (i.e. external threads) on the bone formation and bone resorption around dental implant systems.
  • Load-transfer along the bone-implant interface: The factors that influence long-term implant retention as well as those that contribute to immediate loading of the implant systems have been investigated. The influence of implant contour on the load transfer characteristics is of interest along with the load-transfer mechanism from a metallic implant to the surrounding bone along the bone-implant interface.
  • Stability of the implant-abutment connections: Mechanics of a tapered interference fit (TIF) and mechanics of taper integrated screws (TIS) used in connecting an abutment to an implant have been presented by closed form formulas.

More recently, we started work on mathematical modeling of cell aggregation in collaboration with Professor KT Wan. The aim of this work is to uncover the influence of the cell-wall elasticity on the adhesion and aggregation of various cell systems including bacterial colonies and metastatic growths in tissue.


Particle Based Manufacturing Methods

Small particles are used in a wide range of traditional manufacturing processes where the function and properties of a surface needs to conform to different operational guidelines. This work includes theoretical modeling and experimental research in the following areas. In all three cases the particle-to-surface interactions are affected by multi-physics and multi-scale effects. Our group has been involved in experimental and theoretical analysis of these manufacturing processes since 2005. We include contact, wear and deformation of non-linear material behavior encountered in these processes, and analytical modeling and finite elements and molecular dynamics simulations.

  • Finite element modeling of cold spray: Cold spray is a material consolidation technique that is typically used to coat metal surfaces by impacting with high velocity metal particles. The exact mechanism of particle cohesion on the surface is not yet determined, yet depending on the materials, the technology is very promising for free-form manufacturing and repair of damaged surfaces. We are developing finite element and molecular dynamics models of the cold spray process that includes high strain-rate plasticity and various metal cohesion models.
  • Particle-wafer-pad interactions in chemical mechanical planarization (CMP): CMP is a polishing technique where a wafer is polished by using a soft porous pad and chemically active, abrasive slurry. We developed a hierarchical contact mechanics model of particle to wafer interactions starting from single particles and extending to multiple entrapped particle mechanics interacting with a rough pad and rigid surface. On the experimental side, we performed the first CMP of Niobium, for Superconducting Radio Frequency (SRF) resonator cavity applications.
  • Fluid jet polishing: Concave side of closed surfaces (e.g., SRF resonator cavity) can be manipulated (i.e. cleaned/formed/polished) by a slurry jet.