Vibrations in stainless steel turning: multifractal and wavelet approaches

We investigate the experimental data of the turning process and the appearance of chatter vibrations. We focused on the turning of stainless steel as the example of a special material, which belongs to a hardly machinable class. To characterize the vibration properties we used statistical, multifractal, and wavelet analyses. The multifractal approach estimates complexity of the examined time series of the cutting thrust force. We report that the evolution of the vibration towards fairly large amplitude unwanted chatter with the increasing cutting depth coincides with lowering of the complexity. The results have been confirmed by continuous wavelet analysis

Orthogonal cutting process modelling considering tool-workpiece frictional effect

15th CIRP Conference on Modelling of Machining Operations (15th CMMO) Acknowledgements Financial support of Structural Funds in the Operational Programme - Innovative Economy (IE OP) financed from the European Regional Development Fund - Project ”Modern material technologies in aerospace industry”, POIG.01.01.02-00-015/08-00 is gratefully acknowledgedPeer reviewedPublisher PD

Vibrations in stainless steel turning: multifractal and wavelet approaches

We investigate the experimental data of the turning process and the appearance of chatter vibrations. We focused on the turning of stainless steel as the example of a special material, which belongs to a hardly machinable class. To characterize the vibration properties we used statistical, multifractal, and wavelet analyses. The multifractal approach estimates complexity of the examined time series of the cutting thrust force. We report that the evolution of the vibration towards fairly large amplitude unwanted chatter with the increasing cutting depth coincides with lowering of the complexity. The results have been confirmed by continuous wavelet analysis

Dynamics and Application of Modern, Smart, and Active Elements or Structures

The Special Issue (SI) “Dynamics and Application of Modern, Smart, and Active Elements or Structures” is focused on covering all of the newest outcomes and trends in the nonlinear mechanics of systems and structures with smart, active, and modern materials [...

Biomechanics of the Human Middle Ear with Viscoelasticity of the Maxwell and the Kelvin–Voigt Type and Relaxation Effect

The middle ear is one of the smallest biomechanical systems in the human body and is responsible for the hearing process. Hearing is modelled in different ways and by various methods. In this paper, three-degree-of-freedom models of the human middle ear with different viscoelastic properties are proposed. Model 1 uses the Maxwell type viscoelasticity, Model 2 is based on the Kelvin–Voigt viscoelasticity, and Model 3 uses the Kelvin–Voigt viscoelasticity with relaxation effect. The primary aim of the study is to compare the models and their dynamic responses to a voice excitation. The novelty of this study lies in using different models of viscoelasticity and relaxation effect that has been previously unstudied. First, mathematical models of the middle ear were built, then they were solved numerically by the Runge–Kutta procedure and finally, numerical results were compared with those obtained from experiments carried out on the temporal bone with the Laser Doppler Vibrometer. The models exhibit differences in the natural frequency and amplitudes near the second resonance. All analysed models can be used for modelling the rapidly changing processes that occur in the ear and to control active middle ear implants

Sound Transmission in the First Nonlinear Model of Middle Ear with an Active Implant

This paper shows an influence of a transducer of a middle ear implant on ear dynamics on the basis of the multi-degree-of-freedom biomechanical system. Results of numerical simulations of an ear model with implant are compared with those of the healthy middle ear. Two variants of damping are analysed. The first one typical for a normal healthy middle ear structure and the second one describes pathological properties of the human ear. Moreover, the behaviour of the transducer under various external excitations is investigated. For some set of parameters, the middle ear with the implant behaves regularly but sometimes even chaotically in case of strong excitation

Numerical research of biomechanical system with SMA prosthesis

In this paper the modelling of special biomechanical mechanism and application of shape memory materials are presented. The model of the human middle ear is made as multibody system. The basic 3dof ear model of the healthy middle ear is modified to represent the damaged ear. A damaged of the ossicular chainis taken into account by adding gap in visco-elastic joints. In addition, an attempt of the ossicles chain reconstruction through prosthesis made of shape memory alloy is presented. Moreover, a new description of the hysteresis sub-loop which characterise prosthesis material is proposed. Finally, dynamic responses of healthy, damaged and reconstructed models of the middle ear are compared by quality index