Numerical Analysis of the Sensitivity of Maximum Impact Force to Parameter Variations in the Drucker–Prager Failure Model for Pneumatic Rock Drilling

Jianbing Pei, Dongfang Li, Ming’an Zhou, Huiyi Zhu, Fangzan Luo, Zengyang Huang, Wentao Fu, Haibin Lin, Sufen Wang, Lichun Zhou

DOI: https://doi.org/10.64486/m.66.1.9
Online publication date: June 23, 2026

Abstract: This study investigates the rock-breaking process of pneumatic rock drills using the Drucker–Prager (D–P) strength criterion. A numerical drilling model comprising a rigid impact piston, a rigid drill bit, and D–P rock material was developed in ANSYS LS-DYNA. A sensitivity analysis was performed to evaluate the influence of key material parameters on the maximum impact force between the drill bit and rock. Mesh independence was confirmed with an optimal rock element size of 1.000 mm. The effects of maximum principal strain at failure, rock density, elastic shear modulus, Poisson’s ratio, friction angle, dilation angle, and cohesion were examined over a variation range of ±10 % to ±50 %. Results show that the elastic shear modulus has the strongest influence on the maximum impact force, exhibiting an approximately linear positive relationship. The maximum principal strain at failure also significantly affects impact force, whereas density and Poisson’s ratio produce non-monotonic responses. Friction and dilation angles show strong sensitivity within a limited angular range, while cohesion has only a minor effect. Furthermore, the elastic shear modulus remains the dominant parameter even under different failure-strain conditions, indicating an interaction between stiffness and failure characteristics. The findings provide guidance for predicting drilling forces, optimizing drill-bit design, and improving drilling efficiency through better matching of rock properties and drilling parameters.

Keywords: pneumatic rock drilling; Drucker–Prager criterion; finite element modelling; sensitivity analysis; impact force; rock fragmentation

This article is published online first and will appear in Metalurgija, Vol. 66, Issue 1 (2027).