Measurement of Stress Waves Propagation in Percussive Drilling

Abstract

This work describes the results of a test campaign aimed to measure the propagation of longitudinal, torsional, and flexural stress waves on a drill bit during percussive rock drilling. Although the stress wave propagation during percussive drilling has been extensively modeled and studied in the literature, its experimental characterization is poorly documented and generally limited to the detection of the longitudinal stress waves. The activity was performed under continuous drilling while varying three parameters, the type of concrete, the operator feeding force, and the drilling hammer rotational speed. It was found that axial stress wave frequencies and spectral amplitudes depend on the investigated parameters. Moreover, a relevant coupling between axial and torsional vibrations was evidenced, while negligible contribution was found from the bending modes. A finite element model of the drill bit and percussive element was developed to simulate the impact and the coupling between axial and torsional vibrations. A strong correlation was found between computed and measured axial stress spectra, but additional studies are required to achieve a satisfactory agreement between the measured and the simulated torque vibrations.

Automated Stratum Interface Detection Using the Optimized Drilling Specific Energy through Self-Adaptive Logistic Function

“…2 Calculate the cumulative sum s j corresponding to the j-th data point c j , which is defined in Equation (5).…”

“…To achieve the real-time sensing of interface positions during rock formation drilling, numerous scholars have conducted extensive research on feature indicators and recognition algorithms for interface positioning using drilling techniques [5].…”

Nonlinear Dynamics of Vibro-Impacting Indenter

“…From an experimental point of view, Scaccabarozzi and Saggin [18] measured and characterised the propagation of stress waves on a drill bit during percussive rock drilling. Estimation criteria for ensuring efficient rotary percussive drilling with down-the-hole hammers were proposed by Karpov and Petreev [19].…”