... drilled into the tube wall to form opposing hole pairs. Holes of diameters 12.5 mm and 25 mm are also used to assess the effects of hole diameter on energy absorption. Two hole spacing configurations are investigated, one in which the hole pairs are placed at regular intervals of 50 mm along the tube wall...

...Bo-Wun Huang; Jao-Hwa Kuang This study investigates dynamic instability in a high-speed drilling process. A pretwisted beam is used to simulate the drill. The time-dependent nature of the thrust force and the drilling depth is considered in the equation of motion of the drill. A moving Winkler-type...

... of the fluid lost into the fracture was found to be an almost-linearly decreasing function of the fluid yield stress and a linearly increasing function of the borehole pressure, under assumption of linear fracture deformation law. The model developed serves as a first approximation of mud loss during drilling...

..., the result approaches to that of the continuous elastic rod through some fractional power. The analysis is applicable to segmented drill shafts. Contributed by the Applied Mechanics Division of THE AMERICAN SOCIETY OF MECHANICAL ENGINEERS for publication in the ASME JOURNAL OF APPLIED MECHANICS...