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An active and passive control method is presented to suppress chatter vibrations of the spinning and cylindrical composite boring bar by combining the cutting process damping derived from indentation effect with piezoelectric damping stemmed from Macro Fiber Composite (MFC). The kinetic, potential and electrical energies of the composite boring bar based on the continuous distributed function are established by taking the constitutive relations of piezoelectric materials and the derivative feedback algorithm into account. Introducing the viscoelastic, the hysteretic, the process damping forces, the electrical field as well as cutting forces subjected to the boring process system and forming the virtual work of the non-conservative forces, a final nonlinear equation of motion is derived by utilizing extended Hamilton’s principle and Galerkin procedure. Afterward, the dynamic responses of composite boring bar are derived by using the method of multiple time scales. The proposed approach is validated by comparing the present results with those related papers. A combined model considering process damping effect and feedback gain is also confirmed. The influences of machining, internal and external damping and control parameters on vibration response and process stability of the novel composite boring bar are investigated and discussed. The nonlinear model proposed in this paper can assist in achieving optimal design for composite boring bar and improve the machinability of boring process.

The effect of partially distributed internal damping of the Kelvin–Voigt type on the parametric instability of a Timoshenko beam subjected to periodic axial loads is studied. To model the dynamic behavior of the beam, a coupled set of second-order linear ordinary differential equations with periodic coefficients is established by the finite element method. A quadratic eigenvalue equation is derived for a parametrically excited damped system to determine the instability regions of the beam of concern based on Bolotin's method. The effects of internal damping, size and location of the damped segment, ratio of thickness to length and static load factor on the parametric instability of the beam are studied, along with the stabilizing effect of the Kelvin–Voigt damping on the primary parametric resonance presented. The results reveal that the beam with a larger damped segment positioned near the fixed end is dynamically more stable.

A mathematical model is proposed to analyze the stability of composite shafts, considering the internal damping, transverse shear deformation and Poisson’s coupling effect at the same time. The strain–displacement relations are described using the Timoshenko beam theory, and the strain energy and kinetic energy are expressed using the weak form quadrature element method (QEM), for which each nodal point has 4 degrees of freedom. Then, the motion equation of the system is established using the Lagrange equation. The instability thresholds of the composite shaft are determined using the proposed model. The results were compared with those calculated by the equivalent modulus beam theory (EMBT), equivalent single layer theory (ESLT) and simplified homogenized beam theory (SHBT). Good agreement has been achieved. Therefore, the proposed model can be effectively used for the dynamic analysis of composite shafts.

In this paper, the nonlinear damping and forced response behaviors of laminated composite cylindrical shells considering the internal damping of composite materials are investigated. Based on Donnell nonlinear shell theory, the dynamic governing equations of composite cylindrical shells with geometrical nonlinearity are established by using the Hamilton principle, in which the inherent material damping is taken into account by complex modulus method. The dependence of nonlinear damping on vibration amplitude and amplitude–frequency response are analytically obtained by the Galerkin method in conjunction with harmonic balance method. By comparing the results of natural frequency and modal damping with those in the literature, the correctness of the above theoretical analysis is verified. Furthermore, the effects of the circumferential wave number, lamination schemes, vibration amplitude and geometric configuration on the nonlinear damping and forced responses of the composite cylindrical shell with unidirectional, angle-ply and cross-ply laminations are analyzed. The results show that the damping dissipation capacity of the composite cylindrical shell is amplitude-dependent, and the effect of the amplitude on the nonlinear damping characteristics gradually decreases with the increase of the length-to-radius ratio. The ply angle not only affects the value of the resonance peak, but also significantly changes the degree of the soft and hard spring characteristics of the composite cylindrical shell. With the increase of internal material damping, the amplitude-frequency curve of the composite cylindrical shell changes from the coexistence of hard and soft characteristics to the only soft characteristics.

Automotive shocks involve various tiers’ speed for different human body tissues. Knowing the behavior of these tissues, including muscles, in different vibration frequency is therefore necessary. The muscle has viscoelatic properties. Dynamically, this material has variable mechanical properties depending on the vibration frequency. A novel technique is being employed to examine the variation of the mechanical impedance of pork muscle as a function of frequency. A force is imposed on the lower surface of the sample and acceleration is measured on its upper surface. These two parameters are measured using sensors. The sample is modeled by Kelvin–Voigt model. These measures allow deducing the change in the mechanical impedance modulus (/$Z_{\mathrm{\text{exp}}}$/ $=$ /Force: Acceleration/) of pork muscle as a function of vibration frequency. The measured impedance has a resonance of approximately 60Hz. Best-fit parameters of theoretical impedance can be deduced by superposition with the experiment result. The variation of Young’s modulus and internal damping of pig’s muscle as a function of frequency are determined. The results obtained between 5Hz and 30Hz are the same as determined by Aimedieu and al in 2003, therefore validating our technique. The Young’s modulus of muscle increases with the frequency, on the other hand, we note a rating decrease of internal damping.

The paper presents the dynamic behavior of a hollow rotor shaft with internal damping driven by a dissipative coupling. The coupling in the system is absolutely flexible in transverse and bending; however, it is assumed to be torsionally rigid. Bond graph is adopted for modeling as it facilitates the system modeling from the physical paradigm itself, and the model can be easily extended to incorporate modifications. Simulation results show interesting phenomenon of limiting behavior of rotor shaft with internal damping beyond the threshold speed of instability. It is further shown that the shaft entrainment frequency of the rotor shaft primarily depends on the ratio of external and internal damping.