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17 pages, 2411 KiB

Open AccessArticle

Using the Effect of Compression Stress in Fatigue Analysis of the Roller Bearing for Bimodal Stress Histories

by Paweł J. Romanowicz, Dariusz Smolarski and Marek S. Kozień

Materials 2022, 15(1), 196; https://doi.org/10.3390/ma15010196 - 28 Dec 2021

Cited by 11 | Viewed by 2326

A new approach based on the direct spectral method for fatigue analysis of elements subjected to bimodal stress histories, including high compression effects, is proposed. A correction factor, taking into account the influence of the mean compressive stresses, is used in the proposed method. Equivalent amplitude is estimated, based on criteria proposed by Smith, Watson, and Tooper, and by Bergmann and Seeger. The method is presented with example of a thrust roller bearing. Two cases in which the rollers were subjected to constant force 206 N (where constant amplitude stresses occurred in the rollers) and cyclic force (where bimodal stresses with variable amplitudes occurred in the rollers) are studied. It is observed that multiaxial fatigue criteria (Crossland, Papadopoulos) do not include the influence of bimodal stresses and should not be used for such loading conditions. The proposed method includes both kinds of stress waveforms in the fatigue analysis and can be applied for the accurate identification of stress components and the determination of fatigue life. The damage rate calculated by the proposed approach for rollers subjected to a cyclic force (equivalent load equal to 151 N) was 0.86, which is in good agreement with the recommendations provided in the literature. The obtained accuracy of the proposed method is above 95%. Full article

(This article belongs to the Special Issue Study on Cyclic Mechanical Behaviors of Materials)

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17 pages, 3924 KiB

Open AccessArticle

Numerical and Experimental Investigation of Cumulative Fatigue Damage under Random Dynamic Cyclic Loads of Lattice Structures Manufactured by Laser Powder Bed Fusion

by Marco Pisati, Marco Giuseppe Corneo, Stefano Beretta, Emanuele Riva, Francesco Braghin and Stefano Foletti

Metals 2021, 11(9), 1395; https://doi.org/10.3390/met11091395 - 3 Sep 2021

Cited by 9 | Viewed by 3358

Abstract

Lattice structures are lightweight engineering components suitable for a great variety of applications, including those in which the structural integrity under vibration fatigue is of paramount importance. In this work, we experimentally and numerically investigate the dynamic response of two distinct lattice configurations, in terms of fatigue damage and life. Specifically, Face-Centered-Cubic (FCC) and Diamond lattice-based structures are numerically studied and experimentally tested under resonant conditions and random vibrations, until their failure. To this end, Finite Element (FE) models are employed to match the dynamic behavior of the system in the neighborhood of the first natural frequency. The FE models are employed to estimate the structural integrity by way of frequency and tip acceleration drops, which allow for the identification of the failure time and a corresponding number of cycles to failure. Fatigue life under resonant conditions is well predicted by the application of conventional multiaxial high cycle fatigue criteria to the local state of stress. The same approach, combined with the Rainflow algorithm and Miner’s rule, provides good results in predicting fatigue damage under random vibrations. Full article

(This article belongs to the Special Issue Fracture, Fatigue, and Structural Integrity of Metallic Materials and Components Undergoing Random or Variable Amplitude Loadings)

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12 pages, 3064 KiB

Open AccessArticle

Lifetime Assessment for Multiaxial High-Cycle Fatigue Using Twin-Shear Unified Yield Criteria

by Haoran Li, Jiadong Wang, Juncheng Wang, Ming Hu and Yan Peng

Metals 2021, 11(8), 1178; https://doi.org/10.3390/met11081178 - 24 Jul 2021

Cited by 1 | Viewed by 2187

Abstract

In this paper, a life prediction model associated with maximum principal stress and equivalent shear amplitude based on twin-shear unified yield criterion for multiaxial high-cycle fatigue is proposed. The equivalent shear amplitude is the normalized format of the equivalent shear amplitude based on clusters of yield criteria embodying Tresca and the linearization of Huber-von Mises, extending the application to metallic materials. Simultaneously, the effect of mean stress on multiaxial high-cycle fatigue is considered in the proposed model. As an assessment of the new prediction model, the criterion is compared with experimental data of aluminum alloy LY12CZ and carbon structural steel SM45C published in the relevant literature, which shows that most of the data are located within an error range of less than two times the data and are in good agreement with the experiment. Moreover, the proposed model is also compared with other models, such as McDiarmid, Liu, and Freitas, to validate its competitiveness. Full article

(This article belongs to the Special Issue Computational Mechanics of Fatigue and Fracture in Metallic Materials)

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25 pages, 1806 KiB

Open AccessArticle

Validating the Methods to Process the Stress Path in Multiaxial High-Cycle Fatigue Criteria

by Jan Papuga, Eva Cízová and Aleksander Karolczuk

Materials 2021, 14(1), 206; https://doi.org/10.3390/ma14010206 - 4 Jan 2021

Cited by 10 | Viewed by 2777

Abstract

The paper discusses one of the key features in the multiaxial fatigue strength evaluation—the procedure in which the stress path is analyzed to provide relevant measures of parameters required by multiaxial criteria. The selection of this procedure affects the complete equivalent stress derived for any multiaxial load combinations. Three major concepts—the minimum circumscribed circle, minimum circumscribed ellipse, and moment of inertia methods—are described. Analytical solutions of their evaluation for multiaxial stress state with components described by harmonic functions are provided. The concepts are validated on available experimental data when included into six different multiaxial fatigue strength criteria. The results show that the moment of inertia results in too conservative results. Differences between both methods of circumscribed entities are much smaller. There are indications however that the minimum circumscribed ellipse solution works better for critical plane criteria and for the criteria based on stress tensor transformation into the Ilyushin deviatoric space. On the other hand, the minimum circumscribed ellipse solution tends to shift integral criteria to the conservative side. Full article

(This article belongs to the Special Issue Fatigue Life under Multiaxial Load Conditions)

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19 pages, 23491 KiB

Open AccessArticle

Validation of Multiaxial Fatigue Strength Criteria on Specimens from Structural Steel in the High-Cycle Fatigue Region

by František Fojtík, Jan Papuga, Martin Fusek and Radim Halama

Materials 2021, 14(1), 116; https://doi.org/10.3390/ma14010116 - 29 Dec 2020

Cited by 6 | Viewed by 2480

Abstract

The paper describes results of fatigue strength estimates by selected multiaxial fatigue strength criteria in the region of high-cycle fatigue, and compares them with own experimental results obtained on hollow specimens made from ČSN 41 1523 structural steel. The specimens were loaded by various combinations of load channels comprising push–pull, torsion, bending and inner and outer pressures. The prediction methods were validated on fatigue strengths at seven different numbers of cycles spanning from 100,000 to 10,000,000 cycles. No substantial deviation of results based on the selected lifetime was observed. The PCRN method and the QCP method provide best results compared with other assessed methods. The results of the MMP criterion that allows users to evaluate the multiaxial fatigue loading quickly are also of interest because the method provides results only slightly worse than the two best performing solutions. Full article

(This article belongs to the Special Issue Selected Papers from Experimental Stress Analysis 2020)

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25 pages, 10390 KiB

Open AccessArticle

Micromechanical Modelling of the Influence of Strain Ratio on Fatigue Crack Initiation in a Martensitic Steel-A Comparison of Different Fatigue Indicator Parameters

by Benjamin Josef Schäfer, Petra Sonnweber-Ribic, Hamad ul Hassan and Alexander Hartmaier

Materials 2019, 12(18), 2852; https://doi.org/10.3390/ma12182852 - 4 Sep 2019

Cited by 23 | Viewed by 5280

Abstract

Micromechanical fatigue lifetime predictions, in particular for the high cycle fatigue regime, require an appropriate modelling of mean stress effects in order to account for lifetime reducing positive mean stresses. Focus of this micromechanical study is the comparison of three selected fatigue indicator parameters (FIPs), with respect to their applicability to different total strain ratios. In this work, investigations are performed on the modelling and prediction of the fatigue crack initiation life of the martensitic high-strength steel SAE 4150 for two different total strain ratios. First, multiple martensitic statistical volume elements (SVEs) are generated by multiscale Voronoi tessellations. Micromechanical fatigue simulations are then performed on these SVEs by means of a crystal plasticity model to obtain microstructure dependent fatigue responses. In order to account for the material specific fatigue damage zone, a non-local homogenisation scheme for the FIPs is introduced for lath martensitic microstructures. The numerical results of the different non-local FIPs are compared with experimental fatigue crack initiation results for two different total strain ratios. It is concluded that the multiaxial fatigue criteria proposed by Fatemi-Socie is superior for predicting fatigue crack initiation life to the energy dissipation criteria and the accumulated plastic slip criteria for the investigated total strain ratios. Full article

(This article belongs to the Special Issue Micromechanics: Experiment, Modeling and Theory)

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19 pages, 3281 KiB

Open AccessArticle

Fatigue Damage Accumulation Modeling of Metals Alloys under High Amplitude Loading at Elevated Temperatures

by Jarosław Szusta and Andrzej Seweryn

Metals 2018, 8(12), 1030; https://doi.org/10.3390/met8121030 - 6 Dec 2018

Cited by 1 | Viewed by 3720

Abstract

This article presents an approach related to the modeling of the fatigue life of constructional metal alloys working under elevated temperature conditions and in the high-amplitude load range. The article reviews the fatigue damage accumulation criteria that makes it possible to determine the number of loading cycles until damage occurs. Results of experimental tests conducted on various technical metal alloys made it possible to develop a fatigue damage accumulation model for the LCF (Low Cycle Fatigue) range. In modeling, the material’s damage state variable was defined, and the damage accumulation law was formulated incrementally so as to enable the analysis of the influence of loading history on the material’s fatigue life. In the proposed model, the increment of the damage state variable was made dependent on the increment of plastic strain, on the tensile stress value in the sample, and also on the actual value of the damage state variable. The model was verified on the basis of data obtained from experiments in the field of uniaxial and multiaxial loads. Samples made of EN AW 2024T3 aluminum alloy were used for this purpose. Full article

(This article belongs to the Special Issue Fatigue and Fracture of Traditional and Advanced Structural Alloys)

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