Werkstoffanstrengung bei oszillierender Gleitbewegung

Broszeit, E.; Hess, F.; Kloos, K. H.

doi:10.1002/mawe.19770081208

Cited by 9 publications

(5 citation statements)

References 5 publications

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“…It describes the effect of vibrational loading. As shown in Figure 36, tangential forces by sliding friction acting on a rolling contact increase the equivalent stress and shift its maximum toward the surface on indentation-free raceways (Broszeit et al, 1977). A transition, indicated by solid-line curves, occurs between friction coefficients μ of 0.2 and 0.3: above and below μ=0.25, the increasing maximum of the Tresca equivalent stress is located directly on or near the surface, respectively.…”

Section: Vibrational Contact Loading and Tribological Modelmentioning

confidence: 95%

Tribological Aspects of Rolling Bearing Failures

Gegner¹

2011

Tribology - Lubricants and Lubrication

120

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Introduction Rolling (element) bearings are referred to as anti-friction bearings due to the low friction and hence only slight energy loss they cause in service, especially compared to sliding or friction bearings. The minor wear occurring in proper operation superficially seems to suggest the question how rolling contact tribology should be of relevance to bearing failures. Satisfactorily proven throughout the 20 th century primarily on small highly loaded ball bearings, the life prediction is actually based on material fatigue theories. Nonetheless, resulting subsurface spalling is usually called fatigue wear and therefore included in the discussion below. The influence of friction on the damage of rolling bearings, at first, is strikingly reflected, for instance, in foreign particle abrasion and smearing adhesion wear under improper running or lubrication conditions. On far less affected, visually intact raceways, however, temporary frictional forces can also initiate failure for common overall friction coefficients below 0.1. Larger size roller bearings with extended line contacts operating typically at low to moderate Hertzian pressure, generally speaking, are most susceptible to this surface loading. As large roller bearings are increasingly applied in the 21 st century, e.g. in industrial gears, an attempt is made in the following to incorporate the rolling-sliding nature of the tribological contact into an extended bearing life model. By holding the established assumption that the stage of crack initiation still dominates the total lifetime, the consideration of the proposed competing normal stress hypothesis is deemed appropriate. The present chapter opens with a general introduction of the subsurface and (near-) surface failure mode of rolling bearings. Due to its particular importance to the identification of the damage mechanisms, the measuring procedure and the evaluation method of the material response analysis, which is based on an X-ray diffraction residual stress determination, are described in detail. In section 4, a metal physics model of classical subsurface rolling contact fatigue is outlined. Recent experimental findings are reported that support this mechanistic approach. The accelerating effect of absorbed hydrogen on rolling contact fatigue is also in agreement with the new model and verified by applying tools of material response analysis. It uncovers a remarkable impact of serious high-frequency electric current passage through bearings in operation, previously unnoticed in the literature. Section 5 provides an overview of state-of-the-art research on mechanical and chemical damage mechanisms by tribological www.intechopen.com Tribology -Lubricants and Lubrication 34 stressing in rolling-sliding contact. The combined action of mixed friction and corrosion in the complex loading regime is demonstrated. Mechanical vibrations in bearing service, e.g. from adjacent machines, increase sliding in the contact area. Typical depth distributions of residual stress and X-ray diffraction peak wid...

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Section: Vibrational Contact Loading and Tribological Modelmentioning

confidence: 95%

Tribological Aspects of Rolling Bearing Failures

Gegner¹

2011

Tribology - Lubricants and Lubrication

120

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“…The machining structure of the raceway is smoothed by polishing wear and the residual stress and XRD peak width distributions confirm near-surface fatigue [2]. Additional tangential forces by friction in a rolling-sliding contact raise the equivalent stress and shift its maximum from z 0 for pure radial load towards the surface [5,6]. A transition, indicated in Fig.…”

Section: Micro Friction Model Of the Vibrationally Loaded Rolling Con...mentioning

confidence: 73%

“…As an approximation of the v. Mises stress, Fig. 3 shows a normalized representation of the Tresca stress, σ Tresca /p 0 , as a function of the dimensionless depth coordinate z/a [5]. Here, p 0 and a respectively denote the Hertzian pressure and half the width, i.e.…”

Section: Micro Friction Model Of the Vibrationally Loaded Rolling Con...mentioning

confidence: 99%

Finite Element Analysis of the Rolling-Sliding Contact of Vibrationally Loaded Bearings Based on a Micro Friction Model

Konrad

Nierlich²,

Gegner

2013

MSF

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Mixed friction acting in a rolling contact increases the v. Mises equivalent stress and shifts the maximum towards the surface. Tangential stresses are superimposed to the stress distribution. The resulting position of the maximum v. Mises stress depends on the magnitude of the friction coefficient and is located directly on the surface from values of about 0.25 upwards. The impact of three-dimensional machine vibrations on rolling bearings in operation can cause severe mixed friction running conditions. Residual stress distributions measured on indentation-free raceways indicate high friction coefficients of up to greater than 0.25. The surfaces reveal smoothing of the finishing structure but no adhesive wear. The simulation of the vibrationally loaded rolling-sliding contact is based on the tribological model of localized friction coefficient. This approach avoids seizing by allowing for increased friction only in intermittently changing subareas of the contact at low sliding speed. The macroscopic friction coefficient, meeting a mixing rule, does not exceed 0.1. The finite element method (FEM) is used for the stress analysis. In the first step, a simplified FEM model involves a circumferentially oriented band of high friction coefficient from 0.2 to 0.5 within a cylindrical roller contact. The resulting depth distributions of the v. Mises equivalent stress during overrolling and the corresponding residual stresses are evaluated below the inner ring raceway of the bearing. The features of the FEM model are discussed in detail. The increased sliding friction in the band shifts the maximum of the v. Mises equivalent stress to the surface. Compressive residual stresses are induced in the edge zone. Depending on the applied Hertzian pressure, an additional subsurface peak occurs. First results of the finite element analysis are presented.

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“…8, the depth profiles of the Tresca equivalent stress, which approximates the v. Mises stress, in Fig. 18 reveal the progressive increase and shift of the maximum with rising friction coefficient µ [4]. Absence of smearing implies µ<0.1.…”

Section: Micro Friction Model Of the Vibrationally Loaded Rolling Con...mentioning

confidence: 93%

Service Loading Analysis of Wind Turbine Gearbox Rolling Bearings Based on X-Ray Diffraction Residual Stress Measurements

Gegner¹,

Nierlich²

2013

MSF

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Rolling bearings in wind turbine gearboxes occasionally fail prematurely by so-called white etching cracks. The appearance of the damage indicates brittle spontaneous tensile stress induced surface cracking followed by corrosion fatigue driven crack growth. An X-ray diffraction based residual stress analysis reveals vibrations in service as the root cause. The occurrence of high local friction coefficients in the rolling contact is described by a tribological model. Depth profiles of the equivalent shear and normal stresses are compared with residual stress patterns and a relevant fracture strength, respectively. White etching crack failures are reproduced on a rolling contact fatigue test rig under increased mixed friction. Causative vibration loading is evident from residual stress measurements. Cold working compressive residual stresses are an effective countermeasure.

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Werkstoffanstrengung bei oszillierender Gleitbewegung

Cited by 9 publications

References 5 publications

Tribological Aspects of Rolling Bearing Failures

Tribological Aspects of Rolling Bearing Failures

Finite Element Analysis of the Rolling-Sliding Contact of Vibrationally Loaded Bearings Based on a Micro Friction Model

Service Loading Analysis of Wind Turbine Gearbox Rolling Bearings Based on X-Ray Diffraction Residual Stress Measurements

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