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A drillbit-rock vibro-impact system with a linear rock contact law is considered in this paper. This system is a simplified model to study the drillbit oscillation in a percussive drilling system. The main purpose of this work is to explore the optimized vibration condition of the drillbit to improve the drilling efficiency in practical drilling applications. In order to eliminate the influences of drilling progression on the dynamic analysis of drillbit oscillation, the drillbit oscillation is separated from its drift via oscillation reconstruction. The obtained bounded mathematical model is analyzed by numerical integration and numerical continuation. Based on the codimension-one bifurcations detected by TC-HAT during one-parameter continuation, the two-parameter bifurcation curves are traced by two-parameter continuation. These explored two-parameter bifurcation curves constitute the parameter boundaries for the period-one one-impact oscillation of drillbit, which is verified as the optimal oscillation with the highest drilling efficiency. [ABSTRACT FROM AUTHOR]

• The axial vibration condition of indenter is verified to be independent to the rock rotation. • In order to obtain powerful impacts, the high excitation frequency and amplitude are suggested; however, the high pneumatic pressure should be avoided since it can trigger the chattering of indenter. • The linear force-penetration correlation of rock is better to simulate the deformation of hard rocks under impacts rather than soft rocks with high ductility. This paper focuses on the experimental verification of a dynamical model describing percussive drilling. The design of the experimental apparatus is introduced firstly, and then the dynamic interactions between rock and indenter are studied experimentally by varying three control parameters, including frequency and amplitude of excitation, and pneumatic pressure applied on the indenter. Additionally, the influence of rock stiffness is analyzed by testing different rock-indenter combinations. Meanwhile, the corresponding numerical simulations were conducted showing good agreements with the experimental results. According to the detailed bifurcation analyses, the dynamic responses of indenter mainly display period-one motions which can further develop into period-two motions via period-doubling bifurcation scenarios, or even chaotic motions by period-doubling cascade. The chaotic vibration of indenter can also return to periodic motions via inverse period-doubling bifurcation or fold bifurcation. Although the period-one motion is the main dynamic response in the considered parameter ranges, its impact number per excitation period varies with parameters, which directly affects the maximal impact acceleration of indenter. This results in more energy being dissipated during repeated weak impacts. Therefore, strong impacts are obtained if the indenter is exhibiting the period-one with one-impact motion. For such a purpose, high excitation frequency and amplitude are suggested, however, the high pneumatic pressure should be avoided since it can trigger chattering of the indenter. [ABSTRACT FROM AUTHOR]