Stability Analysis of Cutting Process with Internally Damped Rotating Tapered Composite Cutter Bar

Abstract

Using the cutter bar made with composite rather than metal in high rotating speed milling or boring operations is a new attempt for suppressing chatter of the cutting system. This is because composite material has much higher specific stiffness and damping as well as dynamic stiffness compared to metal. But, for a rotating composite cutter bar, larger internal damping (or rotational damping) occurs, and such damping may cause the rotor instability in the perspective of rotor dynamics. On the other hand, the effect of internal damping of a rotating composite cutter bar on the chatter stability in high speed cutting process is also an important issue worthy of concern. In this paper, a new dynamic model of the cutting system with a rotating composite cutter bar is presented. The cutter bar is modelled as a rotating, cantilever, tapered, composite Euler–Bernoulli shaft, subjected to a regenerative cutting force. Modal damping loss factors are described based on the viscoelastic constitutive relation of composite combined with an energy approach. The governing equations of the system are obtained by employing Hamilton principle. Galerkin method is used to discretize the partial differential equations of motion. The frequency-domain solution of stability proposed by Altintas and Budak [14] is extended and used to predict the chatter stability of the cutting system. The results reveal the inherent relationship between internal damping instability and cutting chatter. The effects of the geometry parameters of the cutter bar, ply angle, stacking sequences, and internal and external damping are examined.

Numerical study on stability of composite cutter bar milling system in rotating coordinate frame

“…In fixed coordinate frame, the chatter equation of the milling system with a rotating composite cutter bar obtained by Galerkin truncation can be expressed in generalized coordinates as follows [21]…”

“…Currently, most studies on the stability analysis of rotating cutter bar are conducted in fixed coordinate frame [15][16][17][18][19][20][21], while only a few are involved in rotating coordinate frame [22,23]. Eynian and Altintas [22] proposed a new prediction method for the milling process with asymmetric structural dynamics in rotating coordinates.…”

Nonlinear dynamics of boring process considering unstable region of CNTs-reinforced composite cutter

“…The kinetic energy of the rotating composite boring bar including the translatory, rotary inertia and gyroscopic effects can be written as [31]:…”

“…where I0 denotes the mass moment of inertia, m denotes the mass per unit length of composite boring bar, D are respectively the extensional and flexural stiffnesses coefficients, which are defined as [31]:…”

An Improved Method of Minimizing Tool Vibration during Boring Holes in Large-Size Structures

“…Chatter vibration elimination during deep hole boring using slender bars was considered in [ 11 , 12 ]. Composite material may have much higher stiffness and damping in comparison to metal, and tests of such properties for chatter suppression were investigated in [ 13 , 14 , 15 , 16 ]. The design and testing of a new dynamic system for boring, based on a tuned holder that increases the dynamic stiffness of slender boring bars by matching the holder natural frequency to the clamped-free boring bar natural frequency, reduced susceptibility to chatter [ 17 ].…”