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Current Research of Dr. Timothy Ovaert

Nano- and Micro-mechanical Characterization of Bone

The objective of this work is to investigate the mechanical behavior of bone using nano- and micro-indentation techniques. The development of numerical and semi-analytical models (at multiple scales) for estimation of mechanical properties, and for correlation with experimental data, is also considered a key element of this research.

Development of Indentation Methods for Mechanical Characterization of Very Soft Materials

Very "soft" materials, whose stiffness is in the kPa range, present major challenges for conventional uniaxial mechanical testing. In our lab, we are developing novel test methods using our nanoindenter in combination with flat indenters, which enables characterization of materials such as gels and thrombi. The development of numerical and semi-analytical models (at multiple scales) for estimation of mechanical/rheological properties, and for correlation with experimental data, is also considered a key element of this research.

New Materials Development for Bio-tribological Applications

Here we are working on the development of new biomaterials, specifically for interfacial sliding applications. The objectives are to develop materials with enhanced mechanical properties while at the same time optimizing tribological performance.

Tribological Investigation of the Chip/Tool Interface by Controlled-Environment Metal Cutting

The tribological interface between the cutting tool surface and the machined chip, as it slides across the surfaces of the tool, is a challenging system to study. The nature of the contact conditions at this chip/tool interface includes limited external access or probing capabilities, potentially high temperature generation, and complex tribo-chemical contact conditions. The objective of this research is to investigate the tribological and physical phenomena that occur at the chip/tool interface during metal cutting operations. This has been accomplished through the development of an existing 1.5 kW turning station, constructed in a vacuum chamber. This system is capable of operation in pressures as low as 10-6 torr, and can be used to investigate a wide variety of gaseous environments. A second objective is to determine if friction at the chip/tool interface may be reduced using a tribo-chemically activated (i.e., via heat, atmosphere, and surface chemistry) boundary lubricant in the form of nano-structured wear resistant coatings containing boundary lubricant species, without externally applied liquid coolant/lubricant mixtures; and if so, to determine how friction is reduced, as monitored by the system's instrumentation.

Scratch Characterization and Modeling of Coated and Uncoated Tribo-systems

In this research, we investigate the resistance of materials to damage via indentation and scratching. Numerical and semi-analytical models of the scratching process (single-point asperity contacts), combined with nano- and micro-scratching experiments, allow us to examine the behavior of the material systems. One application is the retention (or loss) of surface gloss, for example, in multi-layer coated clear-coat finishes and decorative surfaces. Another application is the study of nano-wear phenomena, such as highly polished metallic surfaces sliding against polymer biomaterials.