Analysis of the Fatigue Performance of Thick T-Joint Samples Considering Residual Stresses

2016 ◽  
Author(s):  
J. A. Esnaola ◽  
I. Ulacia ◽  
D. Ugarte ◽  
A. Lopez-Jauregi ◽  
I. Torca ◽  
...  
Keyword(s):  
Residual Stress ◽  
Fatigue Life ◽  
Life Prediction ◽  
Fatigue Performance ◽  
T Joints ◽  
Thick Plates ◽  
Stress Load ◽  
Real Value ◽  
Number Of Passes ◽  
Different Thickness

Residual stress (RS) pattern of thick T-joint welds, which directly affects fatigue life, varies considerably depending on the thickness and number of passes. Nowadays, most approaches to predict fatigue life do not consider RS real value due to the difficulty of estimating them, hence, they tend to be conservatives. However, recent works have demonstrated that considering RS the conservative error in life prediction can be reduced down to around 15%. In the present work, the fatigue performance of multipass T-joints of S275JR plates for a thickness range from 20 to 60mm is evaluated considering RS. It is observed that maximum RS value for thick plates decreases progressively (down to 66% of yield stress). Consequently, fatigue performance of different thickness T-joint samples subjected to the same stress load cycles varies considerably in the HCF regime.

scholarly journals Fatigue life prediction and influencing factors analysis of mesh flexible spoke non-pneumatic tire

2021 ◽  
Vol 13 (10) ◽  
pp. 168781402110524
Author(s):  
Hongxun Fu ◽  
Xiaoxia Chen ◽  
Qiang Zhao ◽  
Zhen Xiao ◽  
Xuemeng Liang
Keyword(s):  
Fatigue Life ◽  
Life Prediction ◽  
Optimization Design ◽  
Structural Parameters ◽  
Prediction Method ◽  
Simulation Method ◽  
Fatigue Life Prediction ◽  
Fatigue Performance ◽  
Driving Safety ◽  
Pneumatic Tire

A mesh flexible spoke non-pneumatic tire is designed to avoid tire burst and other hidden dangers in the traditional pneumatic tires, and improve driving safety. The purpose of this study is to explore the fatigue performance and fatigue life prediction method of the non-pneumatic tire and analyze the influence of structural parameters on the fatigue life of non-pneumatic tire. Based on the crack propagation method of energy release rate by J-integral, the fatigue life of the meshed flexible spoke non-pneumatic tire is predicted. Using numerical simulation method, the influence of key structural parameters, such as the curvature, unit angle and thickness of the lateral spoke and the tread thickness, on tire fatigue life is studied. The results show that the fatigue life prediction method proposed can be used to predict the fatigue life of flexible spoke non-pneumatic tire, and the fatigue life of non-pneumatic tire with flexible spoke can be improved by selecting appropriate structural parameters, which could provide some reference for the structural optimization design of the fatigue performance of the non-pneumatic tire.

Rapid Characterization of Fatigue Performance With Application to Additive Manufactured Components

2020 ◽  
Author(s):  
Dino A. Celli ◽  
M.-H. Herman Shen ◽  
Onome E. Scott-Emuakpor ◽  
Tommy J. George
Keyword(s):  
Experimental Data ◽  
Fatigue Life ◽  
Life Prediction ◽  
Prediction Method ◽  
Experimental Tests ◽  
Parameter Selection ◽  
Process Parameter ◽  
Fatigue Life Prediction ◽  
Fatigue Performance ◽  
Cycles To Failure

Abstract The aim of this paper is to provide a fatigue life prediction method which can concurrently approximate both SN behavior as well as the inherent variability of fatigue efficiently with a limited number of experimental tests. The purpose of such a tool is for the quality assessment and verification of components using Additive Manufacturing (AM) processes and other materials with a limited knowledgebase. Interest in AM technology is continually growing in many industries, such as aerospace, automotive, or biomedical. But components often result in highly variable fatigue performance. The determination of optimal process parameters for the build process can be an extensive and costly endeavor due to either a limited knowledgebase or proprietary restrictions. Quantifying the significant variability of fatigue performance in AM components is a challenging task as there are many causes including machine to machine differences, recycles of powder, and process parameter selection. Therefore, a life prediction method which can rapidly determine the fatigue performance of a material with little or no prior information of the material and a limited number of experimental tests is developed as an aid in process parameter selection and fatigue performance qualification. This is performed by using a previously developed and simplistic energy based fatigue life prediction method, or Two Point method, to predict the inherent variability associated with fatigue performance. The proposed approach is verified by using predicted distributions of stress and cycles to failure and comparing with experimental data at 104 and 106 cycles to failure. SN life prediction is modeled via a modified Random Fatigue Limit (RFL) model where the two RFL model parameters are evaluated using Bayesian statistical inference and stochastic sampling techniques for distribution estimation. This is performed in a dynamic way such that the life prediction model is continually updated with the generation of experimental data.

The Ability of Current Models for Fatigue Life Prediction of Shot Peened Components

2009 ◽  
Vol 417-418 ◽  
pp. 901-904 ◽  
Author(s):  
Ricardo A. Cláudio ◽  
José M. Silva ◽  
Carlos M. Branco ◽  
Jim Byrne
Keyword(s):  
Residual Stress ◽  
Fatigue Life ◽  
Fracture Mechanics ◽  
Shot Peening ◽  
Life Prediction ◽  
Compressive Residual Stress ◽  
Prediction Models ◽  
Critical Distance ◽  
Fatigue Life Prediction ◽  
Distance Methods

It is well known that shot peening has a marked benefit on fatigue life for the majority of applications. This effect is attributed mainly due to the compressive residual stress state at the component’s surface due to shot peening. The present paper evaluates the ability of several fatigue life prediction models, commonly used for general analyses, to predict the behaviour of components with compressive residual stress due to shot peening. Advanced elastic-plastic finite element analyses were carried out in order to obtain stress, strain, strain energy and fracture mechanics parameters for cracks within a compressive residual stress field. With these results several total fatigue life prediction models (including critical distance methods) and fracture mechanics based models were applied in order to predict fatigue life. Fatigue life predictions were compared with several experimental fatigue tests carried out on specimens, representative of a critical region of a compressor disc in a gas turbine aero engine. The results obtained showed that total fatigue life methods, even if combined with critical distance methods, give conservative results when shot peening is considered. Fatigue life was successfully predicted using the method proposed by Cameron and Smith, by adding initiation life to crack propagation life. This last method was also successfully applied for the prediction of non-propagating cracks that were observed during the experimental tests.

scholarly journals Small–Scale Experimental Investigation of Fatigue Performance Improvement of Ship Hatch Corner with Shot Peening Treatments by Considering Residual Stress Relaxation

2021 ◽  
Vol 9 (4) ◽  
pp. 419
Author(s):  
Jin Gan ◽  
Zi’ang Gao ◽  
Yiwen Wang ◽  
Zhou Wang ◽  
Weiguo Wu
Keyword(s):  
Residual Stress ◽  
Surface Roughness ◽  
Fatigue Life ◽  
Stress Relaxation ◽  
Stress Field ◽  
Shot Peening ◽  
Compressive Residual Stress ◽  
Fatigue Performance ◽  
Residual Stress Field ◽  
Residual Stress Relaxation

Ship hatch corner is a common structure in a ship and its fatigue problem has always been one of the focuses in ship engineering due to the long–term high–stress concentration state during the ship’s life. For investigating the fatigue life improvement of the ship hatch corner under different shot peening (SP) treatments, a series of fatigue tests, residual stress and surface topography measurements were conducted for SP specimens. Furthermore, the distributions of the surface residual stress are measured with varying numbers of cyclic loads, investigating the residual stress relaxation during cyclic loading. The results show that no matter which SP process parameters are used, the fatigue lives of the shot–peened ship hatch corner specimens are longer than those at unpeened specimens. The relaxation rate of the residual stress mainly depends on the maximum compressive residual stress (σRSmax) and the depth of the maximum compressive residual stress (δmax). The larger the values of σRSmax and δmax, the slower the relaxation rates of the residual stress field. The results imply that the effect of residual stress field and surface roughness should be considered comprehensively to improve the fatigue life of the ship hatch corner with SP treatment. The increase in peening intensity (PI) within a certain range can increase the depth of the compressive residual stress field (CRSF), so the fatigue performance of the ship hatch corner is improved. Once the PI exceeds a certain value, the surface damage caused by the increase in surface roughness will not be offset by the CRSF and the fatigue life cannot be improved optimally. This research provides an approach of fatigue performance enhancement for ship hatch corners in engineering application.

Fatigue Life Prediction of an Autofrettaged Thick-Walled Pressure Vessel With an External Groove

1991 ◽  
Vol 113 (3) ◽  
pp. 368-374 ◽  
Author(s):  
S. K. Koh ◽  
R. I. Stephens
Keyword(s):  
Residual Stress ◽  
Fatigue Life ◽  
Stress Concentration ◽  
Pressure Vessel ◽  
Life Prediction ◽  
Low Cycle Fatigue ◽  
Fatigue Life Prediction ◽  
Mean Stress ◽  
Cycle Fatigue ◽  
Operating Stress

An autofrettaged thick-walled pressure vessel with an external groove subjected to a pulsating internal pressure can have fatigue failures at the external groove root due to the combination of tensile autofrettage residual stress, operating stress, and stress concentration. To predict the fatigue life of the autofrettaged thick-walled pressure vessel with an external groove, the local strain approach was applied. The residual stress distribution due to autofrettage and the operating stress distribution due to internal pressure were determined using finite element analysis which resulted in theoretical stress concentration factors. To account for the mean stress effects on the fatigue life prediction of the pressure vessel, low-cycle fatigue behavior with several strain ratios was obtained using smooth axial specimens taken from the ASTM A723 thick-walled steel pressure vessel. Fatigue life predictions were made by incorporating the local strains determined from the linear rule and Neuber’s rule and the Morrow and SWT mean stress parameters determined from low-cycle fatigue tests. The predicted fatigue lives were within factors of 2 to 4, compared to simulated experimental fatigue lives based upon fatigue cracks of 2.5 mm in length. These procedures appear to be realistic for evaluating fatigue lives for this complex pressure vessel.

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