scholarly journals The Effects of Test Stress and Microstructure for Cold Dwell Fatigue Properties of Ti-6Al-4V and Its Life Assessment.

2021 ◽  
Vol 70 (4) ◽  
pp. 323-329
Author(s):  
Yutaro OTA ◽  
Keiji KUBUSHIRO ◽  
Yasuhiro YAMAZAKI
Keyword(s):  
Life Assessment ◽  
Fatigue Properties ◽  
Dwell Fatigue ◽  
Test Stress

Assessment of Fatigue Life for High-Temperature Pipeline Welds Using X-Ray Diffraction Technique

2007 ◽  
Vol 353-358 ◽  
pp. 130-133
Author(s):  
Keun Bong Yoo ◽  
Jae Hoon Kim
Keyword(s):  
High Temperature ◽  
Fatigue Life ◽  
Fatigue Damage ◽  
Power Plants ◽  
Low Cycle Fatigue ◽  
Diffraction Method ◽  
Life Assessment ◽  
Fatigue Properties ◽  
X Ray Diffraction ◽  
X Ray

The objective of this study is to examine the feasibility of the X-ray diffraction method for the fatigue life assessment of high-temperature steel pipes used for main steam pipelines, re-heater pipelines and headers etc. in power plants. In this study, X-ray diffraction tests were performed on the specimens simulated for low cycle fatigue damage, in order to estimate fatigue properties at the various stages of fatigue life. As a result of X-ray diffraction tests, it was confirmed that the full width at the half maximum (FWHM) decreased with an increase in the fatigue life ratio, and that the FWHM and the residual stress due to fatigue damage were algebraically linearly related to the fatigue life ratio. From this relationship, a direct assessment of the remaining fatigue life was feasible.

Fatigue Life Analysis of an Automotive Tensioner Through Strain-Life Approach

2015 ◽  
Author(s):  
Maryam Talimi ◽  
Jean W. Zu
Keyword(s):  
Fatigue Life ◽  
Stress Analysis ◽  
Drive System ◽  
Life Assessment ◽  
Fatigue Properties ◽  
Fatigue Life Assessment ◽  
Front End ◽  
Life Analysis ◽  
Fatigue Life Analysis ◽  
Prediction Approach

In this paper, fatigue life assessment of a tensioner is studied through dynamic load analysis, stress analysis, and stress-life fatigue analysis approach. Tensioner is a critical part of an automotive front end accessory drive system, providing pre-tension to the belt. The front end accessory drive systems are responsible for transmitting power from the crankshaft to the accessory components. Due to the engine pulsation, components of the accessory drive including the tensioner are subjected to dynamic loads leading to fatigue failure. The fatigue life assessment of a mechanical component highly depends on loading, geometry, and material properties. In addition, the dynamic behavior of the front end accessory drive is complicated due to coupling between several modes of vibrations in belt, pulleys, and the tensioner arm. Duo to the complexity of the parameters involved and complicated dynamics, the fatigue life analysis of FEAD components is a challenging task. This paper includes three main parts, namely stress analysis, fatigue properties prediction, and life estimation. The dynamic analysis of a generic front end accessory drive system is performed in order to obtain effective loads on the tensioner. Stress state for the tensioner in case of different applied loading conditions is performed via a series of Finite Element (FE) analyses, and the critical region of the part is determined. Finally, fatigue life is estimated through strain-life approach. Modest work has been found in this area providing a comprehensive solution to the fatigue life investigation of power train components. The present study offers a comprehensive modeling approach which predicts the automative tensioner lifetime. The lifetime of any FEAD system components can be determined using the developed fatigue life prediction approach.

Experimental Study on the Fatigue Properties and Reliability for the Steel of Elastic Oil Sump

2013 ◽  
Vol 300-301 ◽  
pp. 1377-1380
Author(s):  
Bin Li ◽  
Zong De Liu ◽  
Peng Duan
Keyword(s):  
Large Scale ◽  
Stress Ratio ◽  
Cyclic Stress ◽  
Probabilistic Methods ◽  
Life Assessment ◽  
Fatigue Properties ◽  
Test Results ◽  
Design Data ◽  
Cyclic Stress Ratio ◽  
Fatigue Design

The elastic oil sump is commonly used as support parts in large-scale thrust bearing. It often operates under fluctuating load conditions during service. So, fatigue analysis of the material of the elastic oil sump is of great significance. In order to obtain the fatigue design data of the material of the elastic oil sump, the systematic tests on uniaxial tension-compression fatigue at room temperature are made. The fatigue limits and the fatigue life curves of the steel of the elastic oil sump are determined at different cyclic stress ratio. The P-S-N equations are calculated by the probabilistic methods. The test results provide a theoretical basis for the safety of life assessment of the elastic oil sump.

Life Assessment of a Coke Drum by Using the Thermal-Mechanical Fatigue Properties and Laser Scanning Approach

2020 ◽  
Author(s):  
Zhiyuan Han ◽  
Guoshan Xie ◽  
Zengchao Wang ◽  
Jianzhong Yin ◽  
Jin Shi
Keyword(s):  
Fatigue Life ◽  
Laser Scanning ◽  
Low Cycle Fatigue ◽  
Complex Loading ◽  
Operating Conditions ◽  
Life Assessment ◽  
Fatigue Properties ◽  
Element Analysis ◽  
Thermal Mechanical Fatigue ◽  
Mechanical Fatigue

Abstract Coke drums are critical equipments in delayed coking plants, which are operated under severe thermal-mechanical conditions by cyclic heating and quenching processes. Cracks are usually developed during service because of severe plastic deformation and low-cycle fatigue. Thus, the assessment of the deformation severity and remaining life is important for safety operating of the coke drums. This study investigated the bulging damage and fatigue life of 6 coke drums after 16 years and 22 years of service in China. A thermal-mechanical fatigue test were first performed to simulate complex loading condition experienced by the coke drum. The thermal-mechanical fatigue life curve of the fabrication material was obtained. Then, a internal laser scanning was employed to measure the deformation and bulges of drum shells. The finite element analysis was developed to calculate the cyclic stress and strain and bulging severity based on the laser mapping and operating conditions. The fatigue life of the coke drum was assessed by the Coffin-Manson-Basquin’s relationship. The life evaluation results of different methods were compared and analyzed. The results showed that a reasonable life of the coke drum can be obtained by using the thermal-mechanical fatigue properties and laser scanning approach.

scholarly journals Fatigue Life Assessment of Rolling Bearings Made from AISI 52100 Bearing Steel

Materials ◽  
2019 ◽  
Vol 12 (3) ◽  
pp. 371 ◽  
Author(s):  
Paweł J. Romanowicz ◽  
Bogdan Szybiński
Keyword(s):  
Fatigue Life ◽  
Load Capacity ◽  
Experimental Tests ◽  
Industrial Applications ◽  
Bearing Steel ◽  
Point Of View ◽  
Life Assessment ◽  
Fatigue Properties ◽  
Fatigue Load ◽  
Rolling Bearings

The rolling bearings used in various industrial applications are exposed to fatigue failure during their operation. Generally, in a practical application, the ISO 281:2007 standard is used for fatigue life assessments of rolling bearings. The application of the formula given in this standard requires knowledge concerning the basic dynamic load rating C. The natural question is raised of whether it is possible to omit the time-consuming experimental tests while still effectively calculating the fatigue load or the load capacity of the bearings. In the paper, the authors propose the application of analytical formulas for stresses in the contact area and its vicinity, and the usage of the multiaxial high-cycle fatigue hypothesis to estimate the maximal fatigue load for the rolling bearings. In the proposed methodology, only the knowledge concerning the fatigue properties of the material and geometry characteristics of the analyzed bearings are demanded. The effectiveness of the authors’ proposal is verified for arbitrarily chosen bearings. The observed discrepancy between the catalogue fatigue load (SKF catalogue) and numerically calculated fatigue load usually does not exceed 10%, which is fully acceptable from an engineering point of view and justifies the approach proposed in the paper. The proposed methodology can be used for the prediction of the fatigue life and optimization of the rolling bearings.

scholarly journals Fatigue of Friction Stir Welded Aluminum Alloy Joints: A Review

2018 ◽  
Vol 8 (12) ◽  
pp. 2626 ◽  
Author(s):  
Hongjun Li ◽  
Jian Gao ◽  
Qinchuan Li
Keyword(s):  
Growth Rate ◽  
Fatigue Life ◽  
Crack Growth Rate ◽  
Crack Growth ◽  
Process Parameters ◽  
Welded Joints ◽  
Welding Process ◽  
Life Assessment ◽  
Fatigue Properties ◽  
Friction Stir

The application fields of friction stir welding technology, such as aerospace and transportation, has high safety requirements and fatigue is the dominant failure mode for weldments. It is of great significance to understand the fatigue properties of friction stir welded joints. This paper provides an overview of the fatigue mechanism, influencing factors, crack growth rate, and fatigue life assessment. It is found that the fatigue performance of friction stir welded joints can be affected by welding process parameters, test environment, stress ratio, residual stress, and weld defect. The optimized process parameters can produce high quality weld and increase the weld fatigue life. Laser peening is an effective post weld treatment to decrease fatigue crack growth rate and improve material fatigue life.

scholarly journals Fatigue life assessment of a railway wheel material under HCF and VHCF conditions

2018 ◽  
Vol 165 ◽  
pp. 09003 ◽  
Author(s):  
H. Soares ◽  
P. Costa ◽  
M. Freitas ◽  
L. Reis
Keyword(s):  
Stress Ratio ◽  
Life Assessment ◽  
Fatigue Properties ◽  
Railway Wheel ◽  
Initial Application ◽  
Fatigue Life Assessment ◽  
Very High Cycle Fatigue ◽  
Ultrasonic Fatigue ◽  
Wheel Material ◽  
Very High

Fatigue damage and life assessment is still an issue and a challenge nowadays. Many different tests can be performed for the assessment of fatigue properties of any given material. In the present study a worn out railway wheel goes under uniaxial fatigue analyses for the high cycle and very high cycle fatigue regimes through the use of a conventional hydraulic machine and an ultrasonic fatigue test, both with a stress ratio of R=-1. For every used specimen, a life cycle is obtained for the corresponding induced specimen and the data is afterwards plotted. All the fracture surfaces of all failed specimens were analysed. The study and initial application of multiaxial ultrasonic fatigue condition and the design of the corresponding specimen for evaluating the wheel material is also presented.

scholarly journals The effect of loading direction on the dwell fatigue properties of Ti-6Al-4V forged bar with highly oriented texture

2020 ◽  
Vol 321 ◽  
pp. 11025
Author(s):  
Kenichi Mori ◽  
Shohtaroh Hashimoto ◽  
Toshiyuki Okui ◽  
Yoshihisa Shirai ◽  
Mitsuo Miyahara
Keyword(s):  
Fatigue Life ◽  
Fracture Surface ◽  
Surface Morphology ◽  
Room Temperature ◽  
Fatigue Properties ◽  
Fracture Surface Morphology ◽  
Creep Tests ◽  
Loading Direction ◽  
Dwell Fatigue ◽  
Oriented Texture

The purpose of this study was to improve our understanding of the effect of macro/micro texture on dwell fatigue properties. The Ti-6Al-4V forged bar with highly oriented texture and fine equiaxed microstructure was used. Dwell fatigue, cyclic fatigue and creep tests were conducted at room temperature by using specimens taken in the longitudinal (L) direction and the transverse (T) direction of the bar. The effects of loading direction on dwell fatigue life and fracture surface morphology were examined in detail. The dwell fatigue life in T direction was shorter than that in L direction. The fracture surface morphologies were characteristically varied by loading waveform, amplitude and directions. In the range of 93 - 95% of 0.2%PS, the characteristic large facets were observed in the T direction in dwell fatigue. Detailed analyses revealed that the large facet consists of multiple initiation facets and propagation facets. The propagation facet plane and crack propagation direction appeared to correspond to alpha (0001) <10-10>. Furthermore, the relationship between strain rate and life time was compared to that for room temperature creep. The deviation from the Monkman-Grant relationship corresponded to the change of the fracture surface morphology.

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