The free vibration and chatter stability of a rotating thin-walled composite bar under the action of regenerative milling force were investigated in this article. The free vibration equations of the rotating thin-walled composite bar were presented and solved by the Galerkin method according to the derived Lagrange equation for the rotating thin-walled composite bar, and the influences of the taper ratio, ply angle, and mode number on the first natural frequency were analyzed. In order to study the chatter stability of the rotating thin-walled composite bar, the time-delay motion equation of the system was derived with consideration of the effects of regenerative milling force and internal/external damping. The two-mode Galerkin method was used to discretize the time-delay free vibration equations, and the semi-discrete method in the time domain was employed to predict the stability lobes. Finally, the correctness of the method was validated, and the stability analysis of the rotating thin-walled composite bar was conducted. Emphatically, the influences of the ply angle, taper ratio, and internal/external damping on the chatter stability of the rotating thin-walled composite bar were analyzed.

Chattering in composite deep-hole boring can directly affect surface processing quality and efficiency and has always been a research hotspot in machining mechanics. In this study, based on Euler–Bernoulli beam theory, the fine control equations for the cutting stability of composite variable-section boring bars were established using the Hamilton principle, in which the sectional change and internal damping of the material were considered. Next, using the Galerkin method and semi-discrete method, the effects of the taper ratio, damping ratio, length-to-diameter ratio, and ply angle on the free vibration characteristics and cutting stability were analyzed in detail. The results show that at a low damping ratio, both the first-order inherent frequency and boring stability can be enhanced with the increase in the taper ratio; at a large damping ratio, increasing the taper ratio can reduce the first-order inherent frequency and boring stability. Finally, the effects of the sectional change on the inherent frequency, displacement response, and convergence were analyzed. A numerical simulation was performed for the model reliability validation. The present research results can provide a theoretical basis and technical guidance for analyzing the cutting stability and fine control of composite variable-section boring bars with large length-to-diameter ratios.

The free vibration behavior and stability of composite milling bar with large aspect ratio are analyzed. Specifically, the free vibration equations are derived based on Euler Bernoulli beam theory and Hamilton’s principle and solved by Galerkin method. In addition, to investigate the stability of the cutting system with a rotating composite milling bar, this study develops an analytical model for regeneration and cutting force fluttering, in which the internal damping, external damping, gyroscopic effect, and inertial effect are considered. The subsequent stability lobes are obtained by the time domain method. Then, the stability of composite and conventional metal milling bar is compared. The effects of internal damping, external viscous damping, ply angle, gyroscopic effect, and inertial effect on cutting stability are analyzed.

Gun drills are widely utilized for deep hole machining due to their high aspect ratio, low stability, and susceptibility to vibrations, which can adversely affect machining accuracy and efficiency. During the machining process, cutting fluid must be injected through the drill rod to facilitate chip removal, resulting in a cross-sectional design with circumferential asymmetry. This asymmetry introduces more complex dynamic characteristics compared to conventional circular cross-section rotors. This study develops a Rayleigh rotor model of the gun drill rod and employs the Galerkin method to evaluate its free vibration characteristics and stability. The findings reveal that the gun drill rod exhibits distinct unstable speed ranges compared to circular cross-section rotors. Furthermore, the impact of various dimensional factors on the free vibration characteristics and stability of gun drill pipes was explored through detailed examination. The theoretical results were validated through comparative analysis with ANSYS simulations, confirming the reliability of the findings in this study.

Gun drills are widely utilized for deep hole machining due to their high aspect ratio, low stability, and susceptibility to vibrations, which can adversely affect machining accuracy and efficiency. During the machining process, cutting fluid must be injected through the drill rod to facilitate chip removal, resulting in a cross-sectional design with circumferential asymmetry. This asymmetry introduces more complex dynamic characteristics compared to conventional circular cross-section rotors. This study develops a Rayleigh rotor model of the gun drill rod and employs the Galerkin method to evaluate its free vibration characteristics and stability. The findings reveal that the gun drill rod exhibits distinct unstable speed ranges compared to circular cross-section rotors. Furthermore, the impact of various dimensional factors on the free vibration characteristics and stability of gun drill pipes was explored through detailed examination. The theoretical results were validated through comparative analysis with ANSYS simulations, confirming the reliability of the findings in this study.

This paper introduces bending anisotropy of gun drill rods, caused by asymmetric cross-section, into chatter stability analysis. A dynamic model considering different stiffnesses along the two principal inertia axes is established. The Galerkin method and semi-discretization method are used to solve the governing equations and generate stability lobe diagrams. Parameter sensitivity analysis shows that drill rod length and material damping coefficient are high-sensitivity parameters, while coolant hole size and eccentric position are low-sensitivity ones. The results reveal the mechanism of bending anisotropy on stability and provide theoretical guidance for chatter suppression in deep-hole machining.