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A novel internal rotor bend actuator is presented that enables compensating strains to be applied about the rotor centre. Axial reaction tubes are used to maintain the structural stability of the bend actuator and to provide feedback on the level of actuation. The system is powered by an onboard battery and the actuation is derived from the operation of lead screw motors. The actuation is commanded wirelessly, thus providing the functionality for an autonomous rotor. The integrated rotor is demonstrated in isolation via laser tracker measurements and for the rotating prototype system. Actuated bending gave rise to radial displacements at the central point relative to shaft ends of approximately 50 µm peak-to-peak. These results validate a finite element deformation model. The rotor was levitated on active magnetic bearings, then rolling elements bearings, to demonstrate the synchronous vibration control achievable by static internal bending. The potential now exists for the commanded actuation to compensate for rotor eccentricities arising from manufacturing errors and dynamically induced unbalance for the cancellation of underlying synchronous vibration. • Novel structure bending concept. • Design of an experimental prototype. • Experimental validation of bending capabilities. • Results matching with finite element modelling. [ABSTRACT FROM AUTHOR]

Tire design with respect to vibrational behavior and noise emission is a challenging task due to the large number of parameters and their coupling. Therefore, accurate high fidelity nonlinear Finite Element (FE) models are needed to aid in the design process. The widely used Arbitrary Lagrangian Eulerian (ALE) models, despite their computational efficiency, are limited to rib-slicked tires and require significant effort to consider inelastic material behavior and frictional phenomena. To overcome these limitations a novel nonlinear FE tire model is presented based on the Total Lagrangian (TL) formulation. The TL model is compared to the reference ALE model for the case of stationary rolling on a smooth and a rough road surface. The observed match of the TL model with respect to the hub and contact forces proves the feasibility of using the TL formulation in the context of rolling contact tire simulations. Therefore, the TL model can be seen as a valid alternative to the frequently used ALE models. • High fidelity nonlinear Finite Element models are required in the tire design process. • The Arbitrary Lagrangian Eulerian formulation poses limitations in modeling. • A nonlinear Finite Element Total Lagrangian tire model is presented. • The behavior of the Total Lagrangian matches the Arbitrary Lagrangian Eulerian model. [ABSTRACT FROM AUTHOR]

Abstract The aim of this paper is to develop a full Finite Element (FE) computational method for the dynamics of unstable frictional rolling contact systems in order to calculate reference solutions in many applications, especially curve squeal for railway transportation but also roller bearing or metal cutting. The proposed method is characterized by the use of a fine FE discretization of the contact surface in a Eulerian frame, nonlinear frictional contact laws and model reduction techniques. An application to the frictional rolling contact between two annular cylinders is presented in both quasi-static and dynamic cases with mode coupling instabilities. The validation of the approach in quasi-static conditions is carried out by comparison with CONTACT software. Stability and transient results show that the technique is able to simulate friction-induced vibrations at high frequencies. Reduced models are tested and show a good agreement with the full model. [ABSTRACT FROM AUTHOR]

The aim of this research is an analysis of full wavefield Lamb wave interaction with impact-induced damage at various impact energies in order to find out the limitation of the wavenumber adaptive image filtering method. In other words, the relation between impact energy and damage detectability will be shown. A numerical model based on the time domain spectral element method is used for modeling of Lamb wave propagation and interaction with barely visible impact damage in a carbon-epoxy laminate. Numerical studies are followed by experimental research on the same material with an impact damage induced by various energy and also a Teflon insert simulating delamination. Wavenumber adaptive image filtering and signal processing are used for damage visualization and assessment for both numerical and experimental full wavefield data. It is shown that it is possible to visualize and assess the impact damage location, size and to some extent severity by using the proposed technique. [ABSTRACT FROM AUTHOR]

The rolling bearing rotor (RBR) system is the kernel of many rotating machines, which affects the performance of the whole machine. Over the past decades, extensive research work has been carried out to investigate the dynamic behavior of RBR systems. However, to the best of the authors' knowledge, no comprehensive review on RBR modelling has been reported yet. To address this gap in the literature, this paper reviews and critically discusses the current progress of mechanical model development of RBR systems, and identifies future trends for research. Firstly, five kinds of rolling bearing models, i.e., the lumped-parameter model, the quasi-static model, the quasi-dynamic model, the dynamic model, and the finite element (FE) model are summarized. Then, the coupled modelling between bearing models and various rotor models including De Laval/Jeffcott rotor, rigid rotor, transfer matrix method (TMM) models and FE models are presented. Finally, the paper discusses the key challenges of previous works and provides new insights into understanding of RBR systems for their advanced future engineering applications. [ABSTRACT FROM AUTHOR]

• A rigid-flexible coupled vehicle system dynamics model is established, which considers the flexible deformation of the brake disc and wheelset as well as wheel polygonal wear. • A thermo-mechanical coupled finite element model of a high-speed train braking system is established, which takes into account nonlinear friction, wheel-rail excitation and thermo-mechanical coupled characteristics. • The accuracies of the dynamics model and finite element model are verified by line and bench tests, respectively. • The effects of measured wheel polygonal wear and wheel polygonal wear order on the temperature and vibration characteristics of braking system are analyzed. To study the effect of wheel polygonal wear (WPW) on temperature and vibration behaviours of a high-speed train braking system, a rigid-flexible coupled vehicle system dynamics model and a thermo-mechanical coupled finite element (FE) model of a braking system are developed in this study. The accuracy of the vehicle dynamics model and FE model are verified by line and bench tests, respectively. The dynamic interactions between different vehicle components, and the nonlinear factors such as wheel − rail interactions, non-linear damper and disc − block frictions are comprehensively considered in the model, which is able to more realistically reflect the service environment of a vehicle system and accurately capture the vibration, temperature and disc − block contact status of a braking system during braking process. Based on the established models, the dynamic behaviours of the braking system excited by WPW is systematically investigated. The results indicate that the standard deviation (SD) of contact area, the root mean square (RMS) values of vibration and the temperature of friction block interface with WPW are much higher compared to those without WPW. Besides, the braking system experiences more intense vibration with the increment of WPW order. [ABSTRACT FROM AUTHOR]

This paper investigates the dynamic behaviors of a perforated gear system considering effects of the gear crack propagation paths and this study focuses on the effects of a crack propagating through the rim on the time-varying mesh stiffness (TVMS) and vibration responses. Considering the effects of the extended tooth contact, a finite element (FE) model of a gear pair is established based on ANSYS software. TVMS of the perforated gear with crack propagating through tooth and rim are calculated by using the FE model. Furthermore, a lumped mass model is adopted to investigate the vibration responses of the perforated gear system. The results show that there exist three periods related to slots of the gear body in a rotating period of the perforated gear. Gear cracks propagating through tooth and rim both reduce the gear body stiffness and lead to reduction of TVMS besides the crack tooth contact moment, and the TVMS weakening for the former is less than that for the latter. Moreover, the results also show that the gear crack propagating through the rim (CPR) has a greater effect on vibration responses than the gear crack propagating through the tooth (CPT) under the same crack level. Vibration level increases with the increasing crack depth, especially for the gear with CPR. [ABSTRACT FROM AUTHOR]

This paper provides insights into the physical mechanism by which defect-related impulsive forces, and consequently, vibrations are generated in defective rolling element bearings. A dynamic nonlinear finite element model of a rolling element bearing with an outer raceway defect was numerically solved using the explicit dynamics finite element software package, LS-DYNA. A hypothesis was developed to explain the numerical noise observed in the predicted vibrations and contact forces, and the noise frequencies were analytically estimated. In-depth analyses of the numerically estimated dynamic contact forces between the rolling elements and the raceways of a bearing, which are not measured in practice, and have not been reported previously, are presented in this paper. Several events associated with the traverse of the rolling elements through the outer raceway defect are elaborated, and the impulsive force generating mechanism is explained. It was found that the re-stressing of the rolling elements that occurs near the end of a raceway defect generates a burst of multiple short-duration force impulses. The modelling results also highlight that much higher contact forces and accelerations are generated on the exit of the rolling elements out of defect compared to when they strike the defective surface. A bearing with a machined outer raceway defect was tested in a controlled experiment; the measured acceleration response compared favourably with the numerically modelled acceleration results, thereby, validating the low- and high-frequency characteristics of the de-stressing and re-stressing of the rolling elements, respectively. [ABSTRACT FROM AUTHOR]