Problems of Analytical Determination of Journal Bearing Bush Fatigue Strength Estimates

Problems connected with determination of stress distribution in sliding layer of thin-walled bearing bushes, investigated in bearing fatigue test rigs, have been presented. Using an example of plain bearings tested in the fatigue machine SMOK (built at the Gdańsk University of Technology) problems with obtaining a convergence of iterative procedure for determining the fatigue strength estimators of bearing alloy surface layer are analyzed. Calculations consisting in successive iterations of pressure distribution in oil film and corresponding elastic deformation of the bearing bush and housing were based on finite-element method and utilized ANSYS program. The objective of calculation was the estimation of values of radial, tangential, axial and reduced stresses in surface layer of the bearing bush corresponding to experimentally determined load magnitudes leading to fatigue cracks initiation. The convergence of analytical procedure has been achieved by the use of a relaxation method.

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The Lorenz model for single-mode homogeneously broadened laser: analytical determination of the unpredictable zone

Open Physics ◽

10.2478/s11534-014-0440-4 ◽

2014 ◽

Vol 12 (3) ◽

Cited By ~ 2

Author(s):

Samia Ayadi ◽

Olivier Haeberlé

Keyword(s):

Analytical Solution ◽

Analytical Procedure ◽

Dissipative System ◽

Period Doubling ◽

Single Mode ◽

Analytical Determination ◽

Pumping Rate ◽

Fifth Order ◽

Doubling Sequence

AbstractWe have applied harmonic expansion to derive an analytical solution for the Lorenz-Haken equations. This method is used to describe the regular and periodic self-pulsing regime of the single mode homogeneously broadened laser. These periodic solutions emerge when the ratio of the population decay rate ℘ is smaller than 0:11. We have also demonstrated the tendency of the Lorenz-Haken dissipative system to behave periodic for a characteristic pumping rate “2C P”[7], close to the second laser threshold “2C 2th ”(threshold of instability). When the pumping parameter “2C” increases, the laser undergoes a period doubling sequence. This cascade of period doubling leads towards chaos. We study this type of solutions and indicate the zone of the control parameters for which the system undergoes irregular pulsing solutions. We had previously applied this analytical procedure to derive the amplitude of the first, third and fifth order harmonics for the laser-field expansion [7, 17]. In this work, we extend this method in the aim of obtaining the higher harmonics. We show that this iterative method is indeed limited to the fifth order, and that above, the obtained analytical solution diverges from the numerical direct resolution of the equations.

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Application of the Concept of Local Fatigue Strength after Shot Peening of Notched Components Based on Numerical Simulations

Materials Science Forum ◽

10.4028/www.scientific.net/msf.638-642.912 ◽

2010 ◽

Vol 638-642 ◽

pp. 912-917

Author(s):

Manuel Klemenz ◽

Volker Schulze

Keyword(s):

Surface Layer ◽

Fatigue Strength ◽

Fatigue Limit ◽

Shot Peening ◽

Surface Characteristics ◽

Complex Stress ◽

Simulated Surface ◽

Induced Changes ◽

Notched Components

Shot Peening is a well established mechanical surface treatment to induce compressive residual stresses and work hardening into the surface layer of components exposed to cyclic loading. Due to the induced changes in the surface layer, the fatigue limit increases significantly. The concept of local fatigue strength is based on the comparison of the locally effective fatigue limit with locally active loads in order to estimate the maximum outer loading that will not exceed fatigue limit. In this paper an approach of using simulated surface characteristics after shot peening for the determination of the local fatigue strength will be presented. The complex stress distribution due to cyclic bending of notched geometries will also be determined by FEM. Finally the simulated estimation of the fatigue limit of differently notched specimens of AISI 4140 will be verified with experimentally determined fatigue limits.

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A Finite Length Plain Journal Bearing Theory

Journal of Tribology ◽

10.1115/1.2928896 ◽

1994 ◽

Vol 116 (3) ◽

pp. 648-653 ◽

Cited By ~ 10

Author(s):

G. Capone ◽

V. D’Agostino ◽

D. Guida

Keyword(s):

Finite Length ◽

Prediction Accuracy ◽

Journal Bearing ◽

Analytical Description ◽

Analytical Determination ◽

Static Characteristics ◽

Set Up ◽

Theoretical Results ◽

Lubrication Conditions

This paper describes a theory for the approximated analytical determination of pressure distribution in the gap of a generic finite length journal bearing in isothermal laminar lubrication conditions as the position assumed by the journal axis varies in a reference frame fixed in the bearing. The same theory is used to set up lubricated finite length journal bearing models in order to obtain an analytical description of the fluid film force, which is characterized by considerable prediction accuracy in the whole field defining the length-diameter ratio. In order to assess the model’s prediction accuracy, the static characteristics of the journal bearing are analytically determined. The theoretical results, presented in the form of diagrams, are compared with the corresponding results obtained numerically.

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Determination of the endurance limit of the surface layer of a part after processing with a blade tool

10.36652/0042-4633-2021-11-56-61 ◽

2021 ◽

pp. 56-61

Author(s):

Keyword(s):

Surface Roughness ◽

Surface Layer ◽

Fatigue Strength ◽

Residual Stresses ◽

Quality Indicators ◽

Work Hardening ◽

Endurance Limit ◽

Layer Surface ◽

Processing Mode

The dependences of the quality indicators of the surface layer of parts on the fatigue strength are analyzed. The dependences are given, taking into account both the quality indicators of the surface layer of the part after processing with the blade tool, and the parameters of the processing mode. Keywords: surface layer, surface roughness, residual stresses, work-hardening depth, endurance limit, blade tool processing. [email protected]

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Adipic acid. Determination in workplace air

Podstawy i Metody Oceny Środowiska Pracy ◽

10.5604/1231868x.1232843 ◽

2017 ◽

Vol 33 (1(91)) ◽

pp. 139-149

Author(s):

Elżbieta DOBRZYŃSKA

Keyword(s):

Adipic Acid ◽

Food Industry ◽

Analytical Procedure ◽

Analytical Determination ◽

Array Detector ◽

Liquid Chromatograph ◽

Total Uncertainty ◽

Workplace Air ◽

Air Sample

Adipic acid is a colorless or white solid. On an industrial scale it is obtained by oxidation of cyclohexanol, cyclohexanone or their mixtures with nitric acid. The compound is utilized in the chemical industry in the production of polyurethanes, polyamides and in the food industry, e.g., as an acidity regulator (E355). Adipic acid is irritating to the eyes. The aim of this study was to develop a method for determining inhalable fraction of adipic acid which enables determination of its concentrations in workplaces air in the range from 1/10 to 2 of MAC values. The developed method is based on the adsorption of adipic acid on a glass fiber filter, a water-extraction and a gas chromatographic analysis of the resulting solution. The tests were performed using a liquid chromatograph (HPLC) 1200 series of Agilent Technologies with diode array detector (DAD). Determinations were performed with application of Allure Organic Acids column (15 cm x 4.6 mm, dp 5 µm). Validation of the method was conducted in accordance with the requirements of the Standard No. EN 482. On the basis of the obtained results, the concentration range was established as 0.036 – 0.72 mg/ml, which corresponds to the concentration range of 0.5 – 10 mg/m3 for 720-L air sample. In the following range the obtained calibration curve was linear as evidenced by the regression coefficient at the level of 0.9999. The overall accuracy of the method was 5.47% and its relative total uncertainty 23.88%. This method enables selective analytical determination of adipic acid in workplace air at the concentration range 0.5 – 10 mg/m3 in the presence of cooccurring compounds, such as cyclohexanone and isopropanol. The method for determining adipic acid is described in the form of analytical procedure in the annex.

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Contribution to Improvement of Fatigue Properties of Zr-4 Alloy: Gradient Nanostructured Surface Layer versus Compressive Residual Stress

Nanomaterials ◽

10.3390/nano11113125 ◽

2021 ◽

Vol 11 (11) ◽

pp. 3125

Author(s):

Donghui Geng ◽

Qiaoyan Sun ◽

Chao Xin ◽

Lin Xiao

Keyword(s):

Residual Stress ◽

Surface Layer ◽

Fatigue Strength ◽

Compressive Residual Stress ◽

Fatigue Cracks ◽

Coarse Grained ◽

Fatigue Properties ◽

Layer Versus ◽

Mechanical Grinding ◽

The Individual

The gradient nanostructured (GNS) layer forms beneath the surface of Zr-4 samples by the surface mechanical grinding treatment (SMGT) process, which increases the fatigue strength apparently due to the synergistic effect of the gradient nanostructured layer and compressive residual stress. The SMGTed Zr-4 samples are subjected to annealing to remove residual stress (A-SMGT) and the individual effect of the GNS layer and compressive residual stress can be clarified. The results show that the gradient nanostructure in the surface is stable after annealing at 400 °C for 2 h but residual stress is apparently removed. Both SMGTed and A-SMGTed Zr-4 samples exhibit higher fatigue strength than that of coarse-grained (CG) Zr-4 alloy. The fatigue fracture of Zr-4 alloy indicates that the hard GNS surface layer hinders fatigue cracks from approaching the surface and leads to a lower fatigue striation space than that of CG Zr-4 samples. The offset fatigue strength of 106 cycles is taken for SMRT-ed, A-SMRT-ed, and CG Zr-4 samples and the results indicate clearly that the GNS surface layer is a key factor for the improvement of fatigue strength of the Zr-4 alloy with surface mechanical grinding treatment.

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Effects of thin hard film deposition on fatigue strength of AA7075-T6

Proceedings of the Institution of Mechanical Engineers Part C Journal of Mechanical Engineering Science ◽

10.1177/0954406220980505 ◽

2020 ◽

pp. 095440622098050

Author(s):

Sergio Baragetti ◽

Emanuele Vincenzo Arcieri

Keyword(s):

Surface Layer ◽

Fatigue Strength ◽

Linear Regression ◽

Physical Vapor Deposition ◽

Crack Nucleation ◽

Fatigue Cracks ◽

Weight Ratio ◽

Film Deposition ◽

Carbon Surface ◽

Industrial Sectors

Thanks to their favorable strength-to-weight ratio, Aluminum-Zinc alloys are often used in high-performance industrial sectors. These alloys are characterized by poor erosion resistance, which could be increased by the deposition of thin films. For example, PVD (Physical Vapor Deposition) films can reduce wear and ensure appreciable performance in aggressive environments. This paper describes the effects of thin hard film deposition on the strength of AA7075 under cyclic loading. Uncoated samples and samples with a DLC (Diamond-Like Carbon) surface layer were tested with a rotating bending fatigue machine within the range of [Formula: see text]–[Formula: see text] cycles. Two regression models were tested to study the relationship between fatigue strength and number of cycles within the range considered. For the samples without the film, even a linear regression can be suitable. With regard to the fatigue strength of the samples with surface layer, a piecewise linear regression is suggested, although a high scatter of experimental data can be observed. Finite element (FE) modelling was used to calculate the stresses induced by bending moment. The bending stresses were added to the residual stresses induced by the film deposition. The maximum value was found beneath the sample surface. Therefore, crack nucleation is expected under the surface of samples with film. The fatigue cracks initiate at the surface in untreated samples.

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