VDMA Verlag

Harald Rosemann: The Weibull Distribution and the Problem of Guaranteed Minimum Lifetimes

For service life tests, a shifted Weibull distribution, also known as the translated or three-parameter
Weibull distribution, is commonly used. The shifted Weibull distribution promises completely faultfree
operation until time ???? = ????0, in other words, in the early stage the process is deterministic. Only after
this phase does the distribution allow random behavior, i.e. from the time ???? = ????0 on, the process is
stochastic. This model, which is based on two consecutive time periods

2022

Sébastien Blachère, Experimental Conformity Level for comparison between endurance tests and life ca

Rolling bearing fatigue life is a stochastic process generally represented by a Weibull-like statistical distribution.
The typical reliability indicator taken as characteristic performance of rolling bearings is the L10 life, i.e. durability
for 10% failure probability among a large bearing population. For a specific bearing under specific operating
conditions, calculation models are available to compute the values of L10. Calculation models must also be compared
to test data and the degree

2022

Sébastien Blachère: Extrapolating Rolling Bearing Life Data to Very High Reliabilities: Friend or Fo

Bearing life is assumed to encounter randomness driven by a Weibull-like statistical distribution. Typical reliability
level taken as performance characterization of rolling bearings is the L10 life (10% of failure among a large
bearings population). Business wise, quantitative estimates of higher reliability levels (below L10) are of importance
for an increasing number of applications, thus they need then to be investigated further. This article aims
are twofold (i) to describe the various

Luc Houpert: Exact calculation of the cumulative failure rate; Study of the four parameter Rosemann’

It is therefore concluded that although powerful and very flexible, Rosemann’s model is not easy to use in practical
situations when dealing with a reduced number of bearing failures (small N number).
An alternative a “New” curve-fitting technique and model (also using four parameters) will be suggested, their
advantages being that only two simple linear curve-fitting could be conducted.

2022

Luc Houpert: A new four parameter reliability model applied to a first-in-N testing strategy using a

Abstract
A new reliability model is suggested in which the failure rate F is calculated as a function of the life L and four
parameters (a1 and L10) and (a2 and L0.1) corresponding to two asymptotic linear models used at large and low F
values respectively (with a2 ≤a1), with a smooth non-linear transition between these two straight lines. L0.1 is the
life corresponding to F=0.001 while L10 is the standard life corresponding to F = 0.1

2022

F. Morosi: Microinclusions Impact on Steel Balls Fatigue Life

Rolling contact fatigue is the main cause of failure in bearings. Among other factors, damage phenomena are related to material properties and manufacturing processes. The damage evolution might be affected by microinclusions present in the material. This influence is related to composition, dimension, shape and location of microinclusions. The relation between microinclusions and fatigue life is investigated for balls undergoing Hertzian pressure fatigue for 100Cr6 steel. Failures are analysed

2020

H.-M. Eckel: Measuring the Kinematic Behavior of the Rolling Elements in a Spindle Bearing

Measuring the Kinematic Behavior of the Rolling Elements in a Spindle Bearing under Axial and Radial Loads
In this paper, a spindle bearing of size 7014 with ceramic balls was investigated. The speeds are up to 30,000 rpm with varying axial preloads and radial forces. The results show that, compared to calculated values, a more uniform orbital velocity curve is measured than calculated values indicate. Thus, the ball advance and retardation tend to be lower than the calculations indicate.

2020

T. Schröder: Full-Size Test Bench Measurements and Validation of a Novel Conical Sliding Bearing ...

After a description of the test bench used for this investigation, the independently measured creep behavior of two bearing rings of a planetary bearing arrangement under varying gear load distributions is presented. For the investigated planetary gear, both rings only show so called gear creep at high loads for all gear load distributions applied.
For the extreme case investigated with an axis inclination on 120 μm it was observed that the creep behavior of the two bearing rings inverted ...

2020

S. Graf: Surface Mutation of the Bearing Raceway During Electrical Current Passage ...

Test results are presented which document the surface mutation of a bearing raceway of an axial bearing during passage of electrical current and operation in the mixed friction area. For the investigation of this matter, a combined mechanical and electrical load is applied to axial bearings of type 51208. For these experiments, the axial
test setup of the modified four ball Apparatus, developed in the research project FVA 650 II, is used.

2020

M. Wolf: Dynamic Simulation of Full Complement Cylindrical Roller Bearings with a Semi-Analytical ..

In this paper, it is critically investigated how significant the runtime and stability advantages of the new contact detection algorithm are in context of an entire multibody simulation in comparison with full numerical models.

2020

M. Oehler: Bearing Selection for high Efficiency Worm Gear Drives

In this work, comparative studies are shown in which different bearing setups are applied to a worm gear drive. Example setups are tapered roller bearings or angular contact ball bearings in adjusted bearing arrangement as well as a locating/non-locating bearing arrangement using four-point contact bearing as locating bearing. A tribological simulation software is used to calculate the load on the worm shaft bearings in axial and radial direction depending on the load situation of the gearbox ..

2020

L. Friedrich: The Utilization of Production-Related Defects for Improving Operating Properties ...

The influence of the orientation of form deviation of hydrodynamic journal bearings were simulated on the basis of the Reynolds equation and evaluated by a worst-case and best-case investigation.
The investigations show that with knowledge of the production-related effects, negative influences of the form deviation can be negated. In addition, a positive influence on the operating properties can be generated by the correct utilization of the form deviations.

2020

J. Gegner: Finite Element Analysis of Two-step Deep Rolling of Bearing Steel for Expansion ...

In the present paper, two-step deep rolling with differently sized and loaded tools is introduced as corrective measure against the weak surface layer. For assessing the influence of process parameters, a finite element analysis is performed on ANSYS 19.2 software. A twodimensional model of the rolling elements pressed onto a raceway is used for residual stress simulation and engineering.

2020

I. Khader:The Influence of Mechanical Stresses on the Diffusion and Accumulation of Hydrogen ...

In this work, a finite element simulation model of a cylindrical roller thrust bearing (CRTB) was created. The simulations enabled studying the diffusion of hydrogen and obtaining qualitative information pertaining to stressassisted diffusion in tribological loading under the influence of residual stresses. The simulations revealed rather
insignificant hydrogen accumulation due to stress-assisted diffusion in comparison to concentration gradient driven diffusion.

2020

G. Breslau: A Fatigue Life Model for Roller Bearings in Oscillatory Applications

This article presents a unified calculation approach for oscillating roller bearings based on the theory of LUNDBERG and PALMGREN, which is compared to the methods of RUMBARGER / JONES and HOUPERT. The relations derived in this work are based on the formulas for calculating the basic dynamic load rating according to the standard. For oscillating motion smaller than the critical amplitude, a more practical calculation method is presented, compared to RUMBARGER / JONES.

2020

F. Schlüter: Influence of Off-Centered Gear Load Distribution on Planetary Bearing Outer Ring Creep

In the contribution the design and calculation process of such conical sliding bearing and corresponding validation measurements of a full-scale demonstrator test in the application of a wind turbine main bearing will be shown. In order to investigate the new bearing concept under real conditions, an extensive measuring campaign has been carried out on a full-scale 1 MW system test bench. Among other matters the load-bearing properties and the overall bearing performance have been investigated.

2020

E. Broitman: Microstructural Analysis of Bearing Steels by a Statistical Nanoindentation Technique

The microstructure of ASTM 52100, X30CrMoN15-1, and AISI M62 steel samples, analyzed by optical
and scanning electron microscopy and by X-ray diffraction, were correlated to the mechanical properties measured at macro- and nanoscale. The distribution of hardness determined from multiple nanoindentation measurements was deconvoluted, obtaining an estimate of the microstructural constituents, and corresponding plastic and elastic
properties at nanoscale.

2020

E. Burbaum: Enhancement of the Insulation Properties of Thermally Sprayed Ceramic Bearing Coatings

Thermally sprayed ceramic coatings partly include desired inhomogeneities like pores, which can be filled by sealers. Common bearings for drive trains in rail vehicles with electrical engines are coated with ceramics by thermal spraying for electrical insulation. The lifetime of these bearings can be reduced by the electrical characteristics of modulated frequency converters in electrical engines. High frequencies and a strong increase of the voltage may lead to a premature breakdown ...

2020

O. Leimann: Calculation Method to Evaluate the Risk of WEC Occurrence in Industrial Applications

White Etching Crack WEC is a premature subsurface initiated failure mode. WEC can occur on bearing components in industrial applications and is reported in wind turbine gear boxes, automotive and other applications.
The failure mode leads to severe bearing failures and is initiated from a sub-surface crack, sometimes seen in combination with so called butterfly’s and seldom related to inclusions. The proposed calculation method will give an estimation of the risk of WEC failure, ...

2020

C. Eberhardt: Simulation Based Design of an Intelligent Hybrid Plain Bearing for Forming Machines

In this paper, a simulation method to design an intelligent hybrid plain bearing (IHPB) and its hydraulics actuators is presented. A substitute model of the bearing composed of lookup tables is derived and integrated in a multiphysics model. An eccentricity control strategy is then developed and tested with a load profile from a deep drawing process. The results show a great potential for the performance of IHPB and its simulations.

2020

D. Bechev et al.: Method for the investigation of the EDM breakdown voltage of grease and oil

Method for the investigation of the EDM breakdown voltage of grease and oil on rolling bearings
Rolling bearing currents cause damage both to the bearing and to the lubricant contained therein. To prevent such damage, the influence of the lubricant in the bearing is becoming increasingly important. By analys- ing the discharge currents and the breakdown voltage in rolling bearings with lubricants of different composition, knowledge of the electrical behaviour of the system (bearing and lubricat

EDM, breakdown voltage, bearing currents

G. Poll et al.: Starved Lubrication in Rolling Contacts-A Review

Starvation is frequently encountered in rolling element bearings. The occurrence of starvation inhibits the generation of pressure and hence results in reduction in film thickness. On the other hand, starvation is helpful to suppress rolling friction and gross skidding of rolling bearings. ...

starvation, rolling contacts, elastohydrodynamic lubrication, grease lubrication, replenishment

M.Y. Sherif et al.: A new through-hardenable high hardenability bearing steel

A new through-hardenable high hardenability bearing steel designed by means of simultaneous optimisation of multiple responses using the desirability function approach

The current work presents a thermodynamics-based approach where the bearing steel alloy design was carried out such that several requirements, for instance high as-quenched hardness and minimum pearlite fraction, were optimised at once making use of inputs like a varying concentration of an alloying element. ...

Alloy design, desirability function, bearing steel, large size bearings

L. Houpert: Novel analytical and numerical calculations in truncated point contact

Novel relationships are given for calculating the contact load, tilting moment and pressure distribution along the roller as a function of the contact deformation and tilting angle for non-truncated or truncated point contacts described using single crown profiles. The analytical results have been calibrated versus some numerical results obtained using a cylinder on cylinder case and an advanced model and tool that account for pressure spikes. ...

Hertzian point contact, truncated point contact, contact pressure, pressure spikes, 2019, Bearing, World, Journal

W. Ma et als: Numerical solution and FFT-based prediction of the hydrodynamic pressure generation

Numerical solution and FFT-based prediction of the hydrodynamic pressure generation of parallel rough surfaces
In general, the component macro-geometry (radius of curvature) determines the pressure generation and the roughness alters it somewhat. However, for parallel surfaces, the surface micro-geometry completely determines the hydrodynamic lubrication. This paper extends earlier work to numerically solve the hydrodynamic pressure generation and load carrying capacity (LCC) of surfaces ...

hydrodynamic lubrication, parallel surfaces, load carrying capacity, FFT techniques

M. Stammler et al.: The influence of oscillation sequences on rolling bearing wear

Oscillating applications for rolling bearings include construction machinery like cranes and excavators and wind turbine pitch and yaw bearings. Due to the widespread use and the specific challenges of wind energy, oscillating applications have gained increased attention by the scientific community in the last years. In wind turbines, the amplitudes, their mean values and external loads of oscillations vary. ...

wear, oscillation, rolling bearings, pitch bearings

S. Rizzo et al.: Dimensional stability on Fatigue Performance of Wheel Bearing Rolling Elements

Rolling bearings are critical automotive and mechanical components. For high loaded bearings, the steel rolling elements are subjected to failure having a direct impact on overall bearing fatigue life performance. Fatigue phenomena involve both rolling contact fatigue and material fatigue damage processes. ...

Bearing, RCF, Rolling elements, Dimensional stability

T. Klenk et al.: Conductive Simmerrings

Conductive Simmerrings help prevent electrical discharge machining in modern electrical powertrains
Electric motors used in e-mobility place completely new requirements on the radial shaft seals, Simmerrings, used in these applications. In the past, research and development work has focused on reducing friction in combustion engines and driveline systems in combination with increasingly higher performance lubricants. ...

EDM electrical discharge machining, conductive nonwovens, bearing damage, impedance spectroscopy, EMI electromagnetic interference