This grant provides funding for establishing the scientific and technological foundation for the measurement of temperatures and forces in the immediate vicinity of the contact zone between the polycrystalline diamond rock cutting insert and the rock and for the formulation of models for their prediction. Sensing will be realized by embedding micro-scale thin film thermo-mechanical sensors into the inserts only a few hundred micrometers away from the contact zone through diffusion bonding two polycrystalline diamond plates, namely, the base plate with the sensors deposited through micro-fabrication techniques and the cover that is in contact with the rock. The realization of this task will necessitate the study of the mechanics of the bonding process and the inter diffusion between the polycrystalline diamond and sensors. Static and dynamic sensor calibration methods will also be developed. The analytical model development, departing from the classical shear plane assumption, will be based on curved macroscopic crack propagation paths and statistical methods to describe the properties of the rock. The numerical Finite Element model will utilize a microcrack-based continuum damage model. Comprehensive experimental verification of the performance of the embedded sensors and of the developed models is also planned. If successful, the results of this research will lead to new tools for more efficient oil- and gas-exploration and extraction capabilities. The availability of the unique embedded sensing technology will potentially result in a quantum leap in the fundamental understanding of rock cutting mechanics and in innovative monitoring/control technologies. The ability of the sensors to provide real-time measurements of process variables from the vicinity of the insert-rock interface will allow the control of optimal penetration rates in rock drilling/cutting operations. The developed methodology will also serve as a platform for the further migration/spillover of embedded micro-sensor technologies into various areas of advanced manufacturing.
