scholarly journals Residual stresses near cold-expanded hole at different stages of high-cycle fatigue by crack compliance data

2021 ◽  
Vol 15 (56) ◽  
pp. 171-196
Author(s):  
Sviatoslav Eleonsky ◽  
Vladimir Pisarev ◽  
Mikhail Zajtsev ◽  
Mikhail Zichenkov ◽  
Marat Abdullin
Keyword(s):  
Residual Stress ◽  
High Cycle Fatigue ◽  
Low Cycle Fatigue ◽  
Speckle Pattern ◽  
Displacement Component ◽  
Electronic Speckle Pattern Interferometry ◽  
Cycle Fatigue ◽  
Residual Stress Field ◽  
Exit Surface ◽  
Plane Displacement

Experimental method for a characterization of high-cycle fatigue evolution of residual stress near cold-expanded hole is developed and implemented. The technique is based on simultaneous measurements of deformation response to narrow notch, inserted in residual stress field, on opposite specimen’s faces by electronic speckle-pattern interferometry (ESPI). Two-side measurements of notch opening displacements are performed when a single notch, emanating from cold-expanded hole edge, is inserted. The transition from in-plane displacement component to residual stress intensity factor (SIF) values follows from the relationships of modified version of the crack compliance method. The approach provides a difference in residual stress values referred to mandrel entrance and exit surface. Notches are inserted at different stages of low-cycle fatigue without applying external load. The results obtained describe fine nuances of residual stress evolution, which cannot be considered as monotonic relaxation.

scholarly journals Damage accumulation near the cold-expanded hole due to high-cycle fatigue by crack compliance method

2021 ◽  
Vol 16 (59) ◽  
pp. 115-128
Author(s):  
Sviatoslav Eleonsky ◽  
Yuri Matvienko ◽  
Vladimir Pisarev ◽  
Michael Zajtsev
Keyword(s):  
Residual Stress ◽  
Fracture Mechanics ◽  
Damage Accumulation ◽  
High Cycle Fatigue ◽  
Initial Point ◽  
Displacement Component ◽  
Electronic Speckle Pattern Interferometry ◽  
Cycle Fatigue ◽  
Fatigue Damage Accumulation ◽  
Plane Displacement

The novel destructive method is implemented for quantitative assessment of fatigue damage accumulation in the stress concentration zone accompanied by residual stress due to cold expansion of the through-thickness hole. Damage accumulation is reached by preliminary cyclic loading of plane specimens with cold-expanded holes. Narrow notches, emanating from the hole edge at different stages of high-cycle fatigue, serve to manifest a damage level. These notches are inserted without applying external load. Deformation response to local material removing, caused by pure residual stress influence, is measured by electronic speckle pattern interferometry (ESPI) in terms of in-plane displacement components. Normalized values of the notch mouth open displacement (NMOD), in-plane displacement component at the initial point of the notch acting in the notch direction (U0), in-plane displacement component at the final point of the notch acting in the notch direction (U1) and the stress intensity factor (SIF) are used as current damage indicators. Numerical integration of curves, describing an evolution of each fracture mechanics parameter over lifetime, produces the damage accumulation function in an explicit form. It is established that all four fracture mechanics parameters give very close results.

scholarly journals Process Induced Residual Stress Effect on Fatigue Lifetime of Automotive Steel Components

2014 ◽  
Vol 996 ◽  
pp. 808-813
Author(s):  
Elias Merhy ◽  
Ngadia Taha Niane ◽  
Bastien Weber ◽  
Philippe Bristiel
Keyword(s):  
Residual Stress ◽  
Heat Affected Zone ◽  
High Cycle Fatigue ◽  
Low Cycle Fatigue ◽  
Welding Process ◽  
Fatigue Loading ◽  
Stress Effect ◽  
Cycle Fatigue ◽  
Residual Stress Field ◽  
Fatigue Lifetime

Metal Active Gas (MAG) welding process of steel sheets generates, in the vicinity of the welding joint, the well-known Heat Affected Zone (HAZ) in which the material presents more microstructural defects compared to the original metal. Since high cycle fatigue is largely dependent on the material microstructure features, the HAZ is considered as the weakest zone under high cycle fatigue loading. In addition, the welding causes, in the Heat Affected Zone, irreversible plastic strains that induce important residual stress fields in this critical zone of the structure. Therefore, in order to properly predict the high cycle fatigue life time of the welded automotive components, it is of primordial importance to first identify and then consider, if necessary, the welding induced residual stress field in the structure modeling. In this work, it is found that residual stresses have non-negligible impact on high cycle fatigue lifetime, while its effect is minor in the low cycle fatigue domain.

Influence of Initial and Welding Residual Stresses on Low Cycle Fatigue and Ratcheting Response Simulations of Elbows

2017 ◽  
Author(s):  
Nazrul Islam ◽  
Tasnim Hassan
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Low Cycle Fatigue ◽  
Simulation Models ◽  
Cycle Fatigue ◽  
Residual Stress Field ◽  
Element Analysis ◽  
Girth Welding ◽  
Stress States ◽  
Welding Processes

Earlier studies [1] showed that the ANSYS software package customized with an advanced rate-independent constitutive model was unable to simulate some of the low-cycle fatigue responses of elbow components. Hence, simulations are performed to investigate the influence of manufacturing and welding residual stresses on elbow low-cycle fatigue responses. The sequentially coupled thermo-mechanical finite element analysis is performed to determine the initial residual stress states in elbows due to the elbow manufacturing processes and welding of elbows to straight pipes. Real-time girth-welding processes are taken into account to simulate the welding induced residual stress field. Incorporating these initial residual stresses in the computations, low-cycle fatigue and strain ratcheting responses are simulated by ANSYS. The simulation responses demonstrate that the influence of manufacturing and welding residual stresses in elbows on its low-cycle fatigue responses is negligible. Hence, the question remains what is missing in the simulation models that some of the elbow low-cycle fatigue responses cannot be simulated.

Mapping of Surface Residual Stress Field by Laser Interferometry Using Stress Relaxation Method

2002 ◽  
Vol 750 ◽  
Author(s):  
Dong-Won Kim ◽  
Nak-Kyu Lee ◽  
Kyung-Hoan Na ◽  
Dongil Kwon
Keyword(s):  
Residual Stress ◽  
Stress Field ◽  
Speckle Pattern ◽  
Thermal Strain ◽  
Laser Interferometry ◽  
Relaxation Method ◽  
Electronic Speckle Pattern Interferometry ◽  
Residual Stress Field ◽  
Surface Residual Stress ◽  
Au Film

ABSTRACTBased on the identification of the residual stress-free state using electronic speckle pattern interferometry (ESPI), we modeled the relaxed stress in annealing, the thermal strain/stress and the residual stress field in case of both single and film/substrate systems by using the thermo-elastic theory and the relationship between relaxed stresses and displacements. Thus we mapped the surface residual stress fields on the indented bulk Cu and the 0.5μm Au film by ESPI. In indented Cu, the normal and shear residual stress are distributed over -800 MPa to 700 MPa and -600 MPa to 600 MPa respectively around the indented point and in deposited Au film on Si wafer, the tensile residual stress is uniformly distributed on the Au film from 500 MPa to 800 MPa. Also we measured the residual stress by the x-ray diffractometer (XRD) for the verification of above residual stress results by ESPI.

Effect of Local Strain on Low Cycle Fatigue Measured by ESPI System

2006 ◽  
Vol 321-323 ◽  
pp. 678-683
Author(s):  
Kyung Su Kim ◽  
Ki Sung Kim ◽  
Kyung Ho Lee ◽  
Jung Min Kwon ◽  
Seong Mo Park ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Low Cycle Fatigue ◽  
Fatigue Cracks ◽  
Speckle Pattern ◽  
Local Strain ◽  
Material Behavior ◽  
Electronic Speckle Pattern Interferometry ◽  
Cycle Fatigue ◽  
Local Strains ◽  
Neuber's Rule

Low cycle fatigue cracks are mainly detected at discontinuous welded locations with high stresses under repeated cyclic static loads due to cargo loading and unloading. Theoretical and analytical methods have been used to estimate the local stress and strain, which affect the prediction of fatigue life, but these methods have difficulties considering stress concentration at notched locations and complicated material behavior of welded joints or heat affected zones. Electronic speckle pattern interferometry(ESPI) system is a nondestructive and non-contact measurement system, which can provide relatively accurate full field strain at critical positions such as welded zones and structurally discontinuous locations. In this study, local strain was measured by ESPI system at the welded cruciform joint, and then low cycle fatigue test was performed. Effect of local strain on low cycle fatigue life was examined by using the strain value measured by ESPI. In order to verify the relations between local strains and fatigue lives, after theoretical local strains and stresses were calculated by using Neuber’s rule, the measured local strains corresponding the experimental fatigue lives were compared with the results of Neuber’s rule and established codes of the British standard and DNV curve.

scholarly journals Influence of stress ratio on residual stress evolution near cold-expanded hole due to low-cycle fatigue by crack compliance data

2020 ◽  
Vol 15 (55) ◽  
pp. 174-186
Author(s):  
Andrey Chernov ◽  
Sviatoslav Eleonsky ◽  
Vladimir Pisarev
Keyword(s):  
Residual Stress ◽  
Stress Ratio ◽  
Low Cycle Fatigue ◽  
Quantitative Description ◽  
Stress Range ◽  
Cycle Fatigue ◽  
Stress Evolution ◽  
Residual Stress Field ◽  
Field Influence

Modified version of the crack compliance method is used for determination of stress intensity factor (SIF) related to narrow notches emanating from cold-expanded holes. These notches are inserted at different stages of low-cycle fatigue under constant external load. It is shown how residual SIF values, generated by residual stress field influence, can be separated from total experimental SIF values. Residual SIF values, obtained at different stage of low-cycle fatigue with the same stress range Δσ  = 350 MPa but different stress  R = –0.4 and  R = –1.0, provide quantitative description of residual stress evolution near cold-expanded hole. It shown that maximal residual stress relaxation of order 20 per cent occurs at 95 lifetime per cent for both loading programs.

Stability and Relaxation of Welding Residual Stresses

2011 ◽  
Vol 681 ◽  
pp. 55-60 ◽  
Author(s):  
Majid Farajian ◽  
Thomas Nitschke-Pagel ◽  
Klaus Dilger
Keyword(s):  
Residual Stress ◽  
Yield Strength ◽  
Residual Stresses ◽  
Low Cycle Fatigue ◽  
Weld Bead ◽  
Small Scale ◽  
Internal Stresses ◽  
Cycle Fatigue ◽  
Residual Stress Field ◽  
Weld Toe

Residual stress relaxation of butt-welded small scale steel specimens under static and cyclic mechanical loading was investigated. The experiments were carried out on different types of steel with yield strengths between 300 and 1200MPa. The x-ray and neutron diffraction techniques were applied for the residual stresses analysis. The maximum values of initial residual stresses were measured at the weld bead centerline and were not as frequently assumed as high as the yield strength of the material. From fatigue point of view the internal stresses at the weld toe are of importance. It was observed that only a fraction of maximum residual stress accommodated in the weld bead centerline, is available at the weld toe. Under static tensile and compressive loading by increasing the load level the residual stress field relaxes continuously. The relaxation sets in with delay under compression since the tensile residual stresses should be first overcome. Under cyclic loading, once the first relaxation takes place further cyclic relaxation is either not considerable or continues moderately depending on loading conditions. In high cycle fatigue the residual stresses are stable until 2x106 cycles. In low cycle fatigue however the variation of the residual stresses continues until failure. This variation is partly related to crack initiation and propagation. The von Misses failure criterion with the local yield strength as material resistance against plastic deformation was able to describe the relaxation of surface welding residual stresses in low cycle fatigue.

Effects of Heat-Treatment Residual Stress on Low Cycle Fatigue Life of a Turbine Disk in PM Superalloy

2015 ◽  
Author(s):  
Rongqiao Wang ◽  
Da Li ◽  
Dianyin Hu ◽  
Yang Hai ◽  
Jun Song
Keyword(s):  
Heat Treatment ◽  
Residual Stress ◽  
Fatigue Life ◽  
Residual Stresses ◽  
Low Cycle Fatigue ◽  
Turbine Disk ◽  
Cycle Fatigue ◽  
Residual Stress Field ◽  
Turbine Disks ◽  
Pm Superalloy

Turbine disks in powder metallurgy (PM) superalloy have been widely used in advanced aeroengines. The production of PM superalloy turbine disks involves a series of heat treatment processes, which would inevitably create residual stresses. It has been proved that the low cycle fatigue (LCF) life of the turbine disk is affected by the residual stresses. The computational simulation of heat treatment is considered as an effective way to evaluate the residual stresses in a turbine disk. A finite element software was used to simulate the heat-treatment processes of a FGH95 turbine disk to obtain the residual stress field. To investigate the relaxation of residual stress in FGH95, smooth bar specimens were measured by X-ray diffraction before and after being loaded. Modified by the residual stresses, SWT model is used to predict the low cycle fatigue life of the turbine disk modified by the residual stress field obtained from the simulation of heat treatment. By the comparison between the prediction modified by the residual stress and the prediction without modification, a considerable decrease in low cycle fatigue life is indicated.

Mapping of Residual Stress Field Based on Residual-Stress-Free State by ESPI Analysis

2003 ◽  
Vol 17 (08n09) ◽  
pp. 1534-1539 ◽  
Author(s):  
Dong Won Kim ◽  
Dongil Kwon
Keyword(s):  
Residual Stress ◽  
Stress Field ◽  
Speckle Pattern ◽  
Free State ◽  
Electronic Speckle Pattern Interferometry ◽  
Residual Stress Field ◽  
Surface Residual Stress ◽  
Stress Mapping ◽  
Stress Free State ◽  
Film Substrate

We study the residual stress mapping of indented Cu by ESPI (electronic speckle pattern interferometry). Based on the identification of the residual stress-free state using electronic speckle pattern interferometry (ESPI), we modeled the relaxed stress in annealing, the thermal strdin/stress and the residual stress field in case of both single and film/substrate systems by using the thermo-elastic theory and the relationship between relaxed stresses and displacements. Thus we mapped the surface residual stress fields on the indented bulk Cu and the 0.5⊔ Au film by ESPI. In indented Cu, the normal and shear residual stress are distributed over -800 MPa to 700 MPa and -600 MPa to 600 MPa respectively around the indented point.

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