Effect of Equivalent Stress Amplitude on Multiaxial Fretting Fatigue Behavior of Al–Zn–Mg Alloy

2020 ◽  
Vol 52 (3) ◽  
pp. 458-469
Author(s):  
X. S. Jiang ◽  
J. X. Jiang ◽  
W. X. Liu ◽  
T. F. Song ◽  
D. Mo
Keyword(s):  
Stress Amplitude ◽  
Fatigue Behavior ◽  
Equivalent Stress ◽  
Fretting Fatigue ◽  
Mg Alloy ◽  
Equivalent Stress Amplitude

Thermal Fatigue Evaluation Method of Pipes by Equivalent Stress Amplitude

2012 ◽  
Author(s):  
Takafumi Suzuki ◽  
Naoto Kasahara
Keyword(s):  
Fatigue Damage ◽  
Thermal Fatigue ◽  
Evaluation Method ◽  
Stress Amplitude ◽  
Equivalent Stress ◽  
Safety Margin ◽  
Evaluation Procedure ◽  
Fatigue Evaluation ◽  
High Cycle Thermal Fatigue ◽  
Equivalent Stress Amplitude

In recent years, reports have increased which are about failure cases caused by high cycle thermal fatigue both at light water reactors and fast breeder reactors. One of the biggest reasons of the cases is a turbulent mixing at a Tee-junction, where hot and cold temperature fluids are mixed, in a coolant system. In order to prevent thermal fatigue failures at Tee-junctions, The Japan Society of Mechanical Engineers (JSME) published the guideline S017-2003 (or JSME guideline) which is an evaluation method of high cycle thermal fatigue damage at a nuclear piping. It has some limitations in terms of its inconstant safety margin and its complexity in evaluation procedure, however. In order to solve these limitations, this paper proposes a new evaluation method of thermal fatigue damage with use of the “equivalent stress amplitude” which represents random temperature fluctuation effects on thermal fatigue damage. Because this new method makes methodology of evaluation clear and concise, it will contribute to improving the guideline for thermal fatigue evaluation.

Investigation Into Cumulative Damage Rules to Predict Fretting Fatigue Life of Ti-6Al-4V Under Two-Level Block Loading Condition1

2003 ◽  
Vol 125 (3) ◽  
pp. 315-323 ◽  
Author(s):  
O. Jin ◽  
H. Lee ◽  
S. Mall
Keyword(s):  
Stress Amplitude ◽  
Fatigue Behavior ◽  
Fretting Fatigue ◽  
Fatigue Tests ◽  
Cumulative Damage ◽  
Order Effects ◽  
Block Loading ◽  
Crack Growth Rates ◽  
Damage Rule ◽  
Repeated Block

The effects of variable amplitude loading on fretting fatigue behavior of titanium alloy, Ti-6Al-4V were examined. Fretting fatigue tests were carried out under constant stress amplitude and three different two-level block loading conditions: high-low (Hi-Lo), low-high (Lo-Hi), and repeated block of high and low stress amplitudes. The damage fractions and fretting fatigue lives were estimated by linear and non-linear cumulative damage rules. Damage curve analysis (DCA) and double linear damage rule (DLDR) were capable to account for the loading order effects in Hi-Lo and Lo-Hi loadings. In addition, the predictions by DCA and DLDR were better than that by linear damage rule (LDR). Besides its simplicity of implementation, LDR was also capable of estimating failure lives reasonably well. Repeated two-level block loading resulted in shorter lives and lower fretting fatigue limit compared to those under constant amplitude loading. The degree of reduction in fretting fatigue lives and fatigue strength depended on the ratio of cycles at lower stress amplitude to that at higher stress amplitude. Fracture surface of specimens subjected to Hi-Lo and repeated block loading showed the clear evidence of change in stress amplitude of applied load. Especially, the repeated two-level block loading resulted in characteristic markers which reflected change in crack growth rates corresponding to different stress amplitudes.

Assessment of Error and Pressure Influence on Total Equivalent Stress Amplitude Calculation by WRC107

2011 ◽  
Author(s):  
Fujun Liu ◽  
Yueqiang Qian ◽  
Zhangwei Ling ◽  
Shuai Kong ◽  
Mulin Zheng
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Shell Theory ◽  
Stress Amplitude ◽  
Equivalent Stress ◽  
External Loading ◽  
Calculation Error ◽  
Fatigue Evaluation ◽  
Chinese Standard ◽  
Equivalent Stress Amplitude

Bulletin WRC107 is most commonly used in attachment design, but still some uncertainties make it difficult to ensure safety in recent use. Two problems in fatigue evaluation were addressed here, first the bulletin is based on shell theory and some other assumption, and for various condition the calculation error is unknown; second pressure is not considered in calculation. To the first problem, an assessment was performed by comparing the total equivalent stress results of WRC107 and of finite element method (FEM). To the second problem, a method from Chinese standard HG20582-1998 Specification for Stress Calculation of Steel Chemical Vessels (HG method) was introduced as a supplement, and the reliability was studied. The results show that, total equivalent stress amplitude calculated by WRC107 may be underestimated, and its error mainly depends on parameters β and γ. Complemented by HG method, WRC107 could be used in calculation of shell under pressure and external loading.

Assessment System of Remaining Life for Bridge Crane Based on the Internet of Things

2013 ◽  
Vol 690-693 ◽  
pp. 3381-3385
Author(s):  
Wen Han Gao ◽  
Ming Fang Li ◽  
Shu Gui Cao ◽  
Deng Hui Liu
Keyword(s):  
Fatigue Life ◽  
Internet Of Things ◽  
Stress Amplitude ◽  
Equivalent Stress ◽  
Crack Size ◽  
The Internet ◽  
Bridge Crane ◽  
The Internet Of Things ◽  
Remaining Fatigue Life ◽  
Equivalent Stress Amplitude

In view of the highly randomness and uncertainty in the working condition of crane, take bridge crane as the research object. Firstly, based on the technology of the internet of things, the load capacity and the number of work cycles would be recorded, and the fatigue stress spectrum would be formed. Secondly, based on the Miners fatigue damage accumulation theory and the rain-flow algorithm, the equivalent stress amplitude would be obtained. Thirdly, curve regression model has been used to characterizing the relationship between the crack propagation and equivalent stress amplitude, and predicting the current crack size. Lastly, taking the predicted value of the crack size into the fracture mechanics formula, and estimated the remaining fatigue life of the bridge crane. The example demonstrated that, it is simple and practical to apply the techniques of the internet of things and the regression forecasting to the data collection and crack size prediction; it not only be able to estimate the remaining fatigue life quickly and accurately, but also be able to overcome the drawback of requiring the initial crack size in the fracture mechanics.

Fretting fatigue behavior and failure characteristics of 35CrMoA steel under elliptical loading path

2021 ◽  
Vol 73 (6) ◽  
pp. 922-928
Author(s):  
Ziao Huang ◽  
Xiaoshan Liu ◽  
Guoqiu He ◽  
Zhiqiang Zhou ◽  
Bin Ge ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Contact Pressure ◽  
Wear Debris ◽  
Stress Amplitude ◽  
Fatigue Behavior ◽  
Fretting Fatigue ◽  
Cyclic Stress ◽  
Loading Path ◽  
Fatigue Wear ◽  
Content Type

Purpose This study aims to understand the multiaxial fretting fatigue, wear and fracture characteristics of 35CrMoA steel under the elliptical loading path. Design/methodology/approach By keeping the contact pressure and torsional shear cyclic stress amplitude unchanged; the axial cyclic stress amplitude varied from 650 MPa to 850 MPa. The fretting fatigue test was carried out on MTS809 testing machine, and the axial cyclic strain response and fatigue life of the material were analyzed. The fretting zone and fracture surface morphology were observed by scanning electron microscope. The composition of wear debris was detected by energy dispersive X-ray spectrometer. Findings In this study, with the increase of axial stress amplitude, 35CrMoA steel will be continuously softened, and the cyclic softening degree increases. The fretting fatigue life decreases unevenly. The fretting scars in the stick region are elongated in the axial direction. The area of fracture crack propagation zone decreases. In addition, the results indicate that wear debris in the slip region is spherical and has higher oxygen content. Originality/value There were few literatures about the multiaxial fretting fatigue behavior of 35CrMoA steel, and most scholars focused on the contact pressure. This paper reveals the effect of axial cyclic stress on fretting fatigue and wear of 35CrMoA steel under the elliptical loading path.

Finite Element Analysis on the Fatigue Stresses of a Railway Vehicle Roller Bearing

2008 ◽  
Vol 44-46 ◽  
pp. 935-941 ◽  
Author(s):  
Feng Lin ◽  
Yong Xiang Zhao
Keyword(s):  
Finite Element ◽  
Stress Amplitude ◽  
Equivalent Stress ◽  
Roller Bearing ◽  
Fe Analysis ◽  
Local Analysis ◽  
Interactive System ◽  
Railway Vehicle ◽  
Load Spectrum ◽  
Equivalent Stress Amplitude

The distributed fatigue stresses of 353130B roller bearing of China freight car with K5 type titling bogie are investigated using an elastic-plastic finite element (FE) analysis. Policy of two steps is applied. First, an integral FE analysis is performed on adapter-bearing-axle-wheel-track interactive system. Second, local analysis is applied to the local axle-bearing-adapter part, in which on the section of axle is with the bound condition obtained from the integral analysis. Wheel contact force spectrum on a curved railway line by on-line inspection is used for the present study. Previous proposed multivariate quadratic regression approach is applied for transferring the load spectrum to the dynamic stress spectrum at a special position of the bearing. Results reveal that the rollers, innerand outer-rings of bearing are subjected to distribute axially equivalent stress amplitude. The closer to axle side, the larger the equivalent stress amplitude. The equivalent stress amplitude of outer ring at the position close to the seal seat is relative larger to that of inner ring. The results are consistency with the shell failures of the bearings in production. Availability of present study is indicated.

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