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Finite element results are presented for frictional contact behavior between a beam and rigid cylinder with either a pinned or roller support under cyclic loading. In the case of a pinned support, a new type of rolling contact is initiated and a steady contact state is achieved owing to frictional shakedown; thus, a certain slope of frictional energy dissipation becomes dominant with respect to the ratio of the mean load to load amplitude. A similar contact behavior is observed when the beam thickness varies and maximum frictional energy dissipation occurs at a certain thickness. For the roller support, only a stick region is observed for all ranges of the loading and unloading phases regardless of the beam thickness, which causes no frictional energy dissipation. These contact behaviors are verified through the consideration of a practical grid-to-rod fretting model. [ABSTRACT FROM AUTHOR]

• The multi-disk rub-impact analysis of a two-spool aero-engine dual-rotor model is performed using the approximate time variational method. • The significance of multi-disk rub-impact studies compared to the single-disk rub-impact problems are discussed based on the response and stability analysis. • Limit point and Neimark-Sacker bifurcations are observed in the response indicating sudden jump and origin of quasi-periodic motion respectively. • The influences of rubbing parameters on the dynamic characteristics of the dual-rotor model are critically evaluated. • The onset of quasi-periodic motion is happening early as the coefficient of friction and contact stiffness are increased. [Display omitted] The main aim of this paper is to propose a numerical procedure for capturing the nonlinear dynamic characteristics of a two-spool aero-engine rotor system undergoing multi-disk rub-impact. In aero-engines, the possibility for the multi-disk rub-impact is high during the fan blade-out (FBO) event and subsequent windmilling action. It intensifies the nonlinear effects on the rotor vibrations and leads to certain undesired circumstances in the engine. The dual-rotor model consists of multi-stage compressors and single-stage turbines that undergo rubbing whenever their deflection exceeds the clearance. The dynamic model of the dual-rotor system is constructed using the tapered Timoshenko beam elements, rigid disks and rolling contact bearings. A proper model reduction technique based on component mode synthesis coupled with the Craig-Bampton substructuring is utilized to reduce the size of the finite element model. A semi-analytic technique called the approximate time variational method is employed to investigate the steady-state response of the system under multi-disk rub impact. Based on the proposed method, the response characteristics of the model are obtained and are verified with the numerical integration results. Compared to the single-disk rub-impact, the nonlinearities are intensified and significant variations are observed in the response characteristics and stability of the system. Period-5, quasi-periodic, and dry friction backward whirl motions are observed in the response for different values of the system parameters. During quasi-periodic motion, some unknown fractional components such as 0.716 ω 1 , 0.766 ω 1 , 0.916 ω 1 and 0.964 ω 1 are appeared in the response. Moreover, the dry friction backward whirl happened with a very large amplitude and it contains a superharmonic frequency component in the response. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents a new method to directly and explicitly calculate all of the components of the sub-surface stress field in plane contacts once the surface contact stress distributions are known. The method is applicable when the contacting bodies have isotropic elastic behaviour, identical mechanical properties and can be modelled as elastic half-planes. Although the method presented here has direct application in the case of plane contacts, it is also applicable in other mechanical problems that lead to a stress distribution at the surface. The procedure described here is applied to find the interior stress field generated by the well-known Carter''s solution for a rolling contact. [Copyright &y& Elsevier]

Abstract: We revisit the classical creep theory for a belt drive system as a rolling contact problem between a rubber ring and rigid cylinders to evaluate the effects of linear viscoelasticity and large strain of the belt on the system in a steady state. We first construct the general theory of belt mechanics for a multi-pulley system by dimensional reduction from 3D extensible, unshearable rod. We then develop the belt mechanics for a linear viscoelastic belt and show that the effect of retardation time can be involved in the effective friction coefficient: the classical Euler''s belt formula can be recovered. Next, we assume that the belt is a neo-Hookean material and examine the effect of large strain of the belt on the contact pressure distribution. We compare the theory with the results by finite element analysis and show that the theory provides good quality. [Copyright &y& Elsevier]

Abstract: The rolling of a cylindrical drum on a stack of separate paper sheets is studied using the finite element method. A two-dimensional model under plane strain conditions is considered. The material of the sheets is modelled by a linearly elastic orthotropic constitutive law. The friction between the various contacting surfaces is modelled by the conventional Coulomb''s law. As a result of the FEM-calculations, the time development of the displacements, stresses and strains of the paper layers is obtained. The slip behaviour at the various contacting surfaces is presented. The micro-slip pattern of the contacting surfaces in the nip area and, particularly, at the trailing edge of the nip, seems to be the main reason for the tightening effect of the nip. The results are compared to the corresponding results for a solid elastic block under the rolling cylinder. [Copyright &y& Elsevier]

Compared with grinding, hard turning may induce a relatively deep compressive residual stress. However, the interactions between the residual stress profile and applied load and their effects on rolling contact stresses and strains are poorly understood, and are difficult to measure using the current experimental techniques due to the small-scale of the phenomena. A new 2-D finite element simulation model of bearing rolling contact has been developed, for the first time, to incorporate the machining-induced residual stress profile instead of only surface residual stresses. Three cases using the simulation model were assessed: (a) measured residual stress by hard turning, (b) measured residual stress by grinding, and (c) free of residual stress. It was found that distinct residual stress patterns hardly affect neither the magnitudes nor the locations of peak stresses and strains below the surface. However, they have a significant influence on surface deformations. The slope and depth of a compressive residual stress profile are key factors for rolling contact fatigue damage, which was substantiated by the available experimental data. Equivalent plastic strain could be a parameter to characterize the relative fatigue damage. The magnitudes of machining-induced residual stress are reduced in rolling contact. The predicted residual stress pattern and magnitude agree with the test data in general. In addition, rolling contact is more sensitive to normal load and residual stress pattern than tangential load. [Copyright &y& Elsevier]