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Horst Biermann - One of the best experts on this subject based on the ideXlab platform.
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investigation of isothermal and thermo mechanical fatigue behavior of the nickel base superalloy in738lc using standardized and advanced test methods
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2016Co-Authors: D Hollander, D Kulawinski, S Henkel, Horst Biermann, Marcus Thiele, C Damm, Uwe GampeAbstract:Abstract The uniaxial and biaxial-planar isothermal fatigue behavior as well as the uniaxial thermo-mechanical fatigue behavior of the nickel-base superalloy IN738LC was investigated at high temperatures using standardized and advanced test technologies. Small scale specimens’ tests were carried out in order to study the specimen size effect and biaxial-planar tests under equibiaxial and shear Loading to investigate the influence of the multiaxial stress state on the isothermal fatigue behavior both at 750 °C. Standardized specimens were used to determine the uniaxial isothermal and thermo-mechanical fatigue behavior under in-Phase and out-of-Phase Loading in the temperature range between 750 °C and 950 °C. The standard specimens’ results particularly served as reference data as well as for the verification of a recently developed lifetime prediction model for thermo-mechanical fatigue Loading. The small scale specimens’ results were in good agreement with standardized specimens. The comparison of fatigue lifetimes of uniaxial and biaxial-planar tests showed that the equivalent strain hypothesis according to von Mises is applicable to correlate the fatigue life of the equibiaxial Loading case within a scatter band of factor two, whereas the shear Loading case was predicted conservatively. Furthermore, the recently developed lifetime prediction model correlated the fatigue lives of the isothermal and thermo-mechanical tests under uniaxial and biaxial-planar Loading as well as literature data. Finally, the deformation and crack growth mechanism were studied.
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isothermal and thermo mechanical fatigue behavior of the nickel base superalloy waspaloy under uniaxial and biaxial planar Loading
International Journal of Fatigue, 2015Co-Authors: D Kulawinski, Anja Weidner, S Henkel, Horst BiermannAbstract:Abstract The thermo-mechanical uniaxial and biaxial-planar fatigue behavior of the forged nickel base superalloy Waspaloy™ was investigated for in-Phase and out-of-Phase Loading between 673 K and 923 K. At these temperatures also the uniaxial and biaxial-planar isothermal material behavior was studied. In order to determine the influence of the multiaxial stress state on the fatigue life biaxial-planar isothermal tests were carried out at three different strain ratios. The uniaxial isothermal lifetimes coincide very well with literature data. A conservative lifetime description for thermo-mechanical in-Phase and out-of-Phase fatigue test was set based on the isothermal tests at the upper temperature. The comparison of lifetimes from uniaxial and biaxial-planar tests shows that the equivalent strain hypothesis according to von Mises correlates the fatigue lives of the different stress states within a scatter band of two. The failure mechanism including crack initiation, crack growth and the macroscopic crack path were studied by scanning electron microscopy. A change from a mainly transgranular crack growth at 673 K to a mostly intergranular fracture at 923 K as well as under thermo-mechanical fatigue Loading was found. The fatigue lives of the isothermal and thermo-mechanical tests under both uniaxial and biaxial-planar Loading were correlated by a new lifetime model which is based on a stress–strain approach.
Magd Abdel Wahab - One of the best experts on this subject based on the ideXlab platform.
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fretting fatigue damage nucleation under out of Phase Loading using a continuum damage model for non proportional Loading
Tribology International, 2018Co-Authors: Nadeem Ali Bhatti, Magd Abdel WahabAbstract:Abstract Damage nucleation involves creation of micro cracks, which are discontinuities in a material considered as continuous at a larger scale. Continuum Damage Mechanics (CDM) approach provides a tool to study damage nucleation under plane and fretting fatigue conditions. Under fretting fatigue conditions, the Loading sequence may produce non-proportional stresses. This paper aims to investigate the effect of non-proportional Loading on damage nucleation. For this purpose, a CDM based damage model for non-proportional Loading is developed and applied to cylindrical pad and flat specimen configuration. The numerical results are also compared with experimental results from literature. It is found that, taking into account the triaxiality function variation in damage law, improves crack initiation lifetime estimation. In addition, a sensitivity analysis is performed by varying stress range and triaxiality function. It is found that for in Phase Loading only the stress range affects the initiation life, whereas, for out of Phase Loading both stress range and triaxiality function affect initiation life, especially at higher ranges.
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a continuum damage mechanics approach for fretting fatigue under out of Phase Loading
Tribology International, 2018Co-Authors: Nadeem Ali Bhatti, Magd Abdel Wahab, Kyvia De Fatima Resende PereiraAbstract:Abstract The phenomenon of fretting fatigue involves multiaxial stress states near the contact interface and is mainly characterized by nucleation and propagation Phases. Based on the mechanism of each Phase, various approaches have been developed to predict damage initiation location and life. This paper aims to investigate the effectiveness of continuum damage mechanics (CDM) approach under in Phase and 90° out of Phase Loading. Two cases with different material and Loading conditions are considered for this analysis. The first case includes constant normal load and Phase difference is generated between axial cyclic stress and tangential load. Whereas in the second case, cyclic normal load is applied and Phase difference is generated between normal load and other two loads i.e. cyclic axial stress and tangential load. The results obtained using CDM approach are compared to those obtained using critical plane (CP) approach. The numerical results are also compared with experimental results from literature. It is observed that, both approaches provide good estimate of initiation location and life for in Phase Loading. With Phase difference of 90°, the initiation locations also match well with the experimental results, however, for life estimation CDM approach has shown better prediction than CP approach, especially at lower loads. In addition, both approaches have shown that with Phase difference of 90°, the fretting fatigue life increases as compared to in Phase Loading.
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a numerical investigation on critical plane orientation and initiation lifetimes in fretting fatigue under out of Phase Loading conditions
Tribology International, 2017Co-Authors: Nadeem Ali Bhatti, Magd Abdel WahabAbstract:Abstract This study focuses on application of critical plane approach to in-Phase and out-of-Phase Loading conditions in fretting fatigue problems. The efficacy of various multiaxial damage criteria is analysed to determine critical plane orientation and initiation life, and is investigated for the first time in case of out-of-Phase Loading condition. Furthermore, our study focuses on the estimation of initiation angle and initiation lives using multiaxial damage criteria. For analysis purpose, the damage criteria are categorized as stress-based (Findley parameter and McDiarmid criterion), strain-based (Brown-Miller criterion and Fatemi-Socie criterion) and virtual strain energy-based (Smith-Watson-Topper criterion and Liu 1 and 2 criteria). It is observed that shear stress and shear strain-based criteria are able to predict both critical plane orientation and fretting fatigue lifetimes, whereas energy-based criteria, which employ normal stress and strain, are only suitable to predict initiation life. The deviation in estimation of initiation life for stress-based criteria is observed to be higher than others if the internal stresses are higher than yield stress. It is shown that initiation can occur on either of the preferred shearing plane depending upon material and Loading conditions. The Phase difference of 90° and 180° increases and decreases the initiation life respectively as compared to in-Phase Loading. In addition, 90° Phase difference introduces more shearing planes for damage nucleation.
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finite element analysis of fretting fatigue under out of Phase Loading conditions
Tribology International, 2017Co-Authors: Nadeem Ali Bhatti, Magd Abdel WahabAbstract:Abstract Fretting fatigue is a complex phenomenon involving various factors, such as slip amplitude, coefficient of friction, shear load and Loading Phase difference. In this study, three numerical models are used to model the effect of both in Phase and out of Phase Loading on contact stresses and damage initiation locations. Three Phase difference angles are considered, i.e. 0°, 90° and 180°, for this purpose. It is observed that Phase difference affects the shear traction and tensile stress profiles at the contact interface, whereas no significant effect is observed on convergence efficiency. It is also shown that, due to increase of stick zone width, the convergence is slower during the unLoading step than during the Loading step. SWT parameter and Ruiz parameter are adopted as two crack initiation criteria in order to investigate their performance in case of out of Phase Loading. The critical locations predicted by both parameters have shown good agreement with experimental results from literature. In addition, it is observed that Phase difference significantly affects the damage initiation location.
Cetin Morris Sonsino - One of the best experts on this subject based on the ideXlab platform.
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assessment of the fatigue behaviour of welded aluminium joints under multiaxial spectrum Loading by a critical plane approach
International Journal of Fatigue, 2006Co-Authors: M. Kueppers, Cetin Morris SonsinoAbstract:Multiaxial stress states occur in many welded constructions like chemical plants, railway carriages and frames of trucks. Depending on the Loading mode, those stresses can have constant and changing principal stress directions. For welded fine grained steel, research results show a severe loss of fatigue life for changing principal stress directions simulated by out-of-Phase bending and torsion compared to constant directions given by in-Phase Loading. However, aluminium welds reveal no influence of changing principal directions on fatigue life compared to multiaxial Loading with constant principal stress directions under constant amplitude and spectrum Loading. This behaviour is not predictable by any conventional hypothesis. A hypothesis on the basis of a combination of local normal and shear stress in the critical plane has been developed and successfully applied to aluminium weldings.
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fatigue strength of laser beam welded thin steel structures under multiaxial Loading
International Journal of Fatigue, 2006Co-Authors: Cetin Morris Sonsino, M. Kueppers, M Eibl, G ZhangAbstract:Abstract The multiaxial fatigue behaviour of thin laser beam welded tube–tube specimens of the structural steel St35 was assessed according to the methodology of the fictitious weld root radius of r f =0.05 mm and the application of the Effective Equivalent Stress Hypothesis (EESH), especially considering the fatigue life reducing influence of out-of-Phase Loading in comparison to in-Phase Loading. The results are applicable for the fatigue design of laser beam welded car body and chassis structures of thin steel sheets ( t
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critical plane approach for the assessment of the fatigue behaviour of welded aluminium under multiaxial Loading
Fatigue & Fracture of Engineering Materials & Structures, 2003Co-Authors: M. Kueppers, Cetin Morris SonsinoAbstract:Multiaxial stress states occur in many welded constructions like chemical plants, railway carriages and frames of trucks. Those stresses can have constant and changing principal stress directions, depending on the Loading mode. Latest research results on welded steel joints show a loss of fatigue life for changing principal stress directions simulated by outer-Phase bending and torsion compared to constant directions given by in-Phase Loading. However, aluminium welds reveal no influence of changing principal directions on fatigue life compared to multiaxial Loading with constant principal stress directions. This behaviour is not predictable by any conventional hypothesis. A hypothesis on the basis of local normal and shear stresses in the critical plane has been developed and applied to aluminium weldings.
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Multiaxial fatigue of welded joints under constant and variable amplitude Loadings
Fatigue & Fracture of Engineering Materials & Structures, 2001Co-Authors: Cetin Morris Sonsino, M. KueppersAbstract:Flange-tube joints from fine grained steel StE 460 with unmachined welds were investigated under biaxial constant and variable amplitude Loading (bending and torsion) in the range of 10 3 to 5 x 10 6 cycles to crack initiation and break-through, respectively. In order not to interfere with residual stresses they were relieved by a heat treatment. In-Phase Loading can be treated fairly well using the conventional hypotheses (von Mises or Tresca) on the basis of nominal, structural or local strains or stresses. But the influence of out-of-Phase Loading on fatigue life is severely overestimated if conventional hypotheses are used. However, the hypothesis of the effective equivalent stress that is introduced leads to fairly good predictions for constant as well as for random variable amplitude loads. Therefore, the knowledge of local strains or stresses is necessary. They are determined by boundary element analyses that are dependent on weld geometry. This hypothesis considers the fatigue-life-reducing influence of out-of-Phase Loading by taking into account the interaction of local shear stresses acting in different surface planes of the material. Further, size effects resulting from weld geometry and Loading mode were included. Damage accumulation under a Gaussian spectrum can be assessed for in- and out-of-Phase combined bending and torsion using an allowable damage sum of 0.35.
D Kulawinski - One of the best experts on this subject based on the ideXlab platform.
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investigation of isothermal and thermo mechanical fatigue behavior of the nickel base superalloy in738lc using standardized and advanced test methods
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2016Co-Authors: D Hollander, D Kulawinski, S Henkel, Horst Biermann, Marcus Thiele, C Damm, Uwe GampeAbstract:Abstract The uniaxial and biaxial-planar isothermal fatigue behavior as well as the uniaxial thermo-mechanical fatigue behavior of the nickel-base superalloy IN738LC was investigated at high temperatures using standardized and advanced test technologies. Small scale specimens’ tests were carried out in order to study the specimen size effect and biaxial-planar tests under equibiaxial and shear Loading to investigate the influence of the multiaxial stress state on the isothermal fatigue behavior both at 750 °C. Standardized specimens were used to determine the uniaxial isothermal and thermo-mechanical fatigue behavior under in-Phase and out-of-Phase Loading in the temperature range between 750 °C and 950 °C. The standard specimens’ results particularly served as reference data as well as for the verification of a recently developed lifetime prediction model for thermo-mechanical fatigue Loading. The small scale specimens’ results were in good agreement with standardized specimens. The comparison of fatigue lifetimes of uniaxial and biaxial-planar tests showed that the equivalent strain hypothesis according to von Mises is applicable to correlate the fatigue life of the equibiaxial Loading case within a scatter band of factor two, whereas the shear Loading case was predicted conservatively. Furthermore, the recently developed lifetime prediction model correlated the fatigue lives of the isothermal and thermo-mechanical tests under uniaxial and biaxial-planar Loading as well as literature data. Finally, the deformation and crack growth mechanism were studied.
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isothermal and thermo mechanical fatigue behavior of the nickel base superalloy waspaloy under uniaxial and biaxial planar Loading
International Journal of Fatigue, 2015Co-Authors: D Kulawinski, Anja Weidner, S Henkel, Horst BiermannAbstract:Abstract The thermo-mechanical uniaxial and biaxial-planar fatigue behavior of the forged nickel base superalloy Waspaloy™ was investigated for in-Phase and out-of-Phase Loading between 673 K and 923 K. At these temperatures also the uniaxial and biaxial-planar isothermal material behavior was studied. In order to determine the influence of the multiaxial stress state on the fatigue life biaxial-planar isothermal tests were carried out at three different strain ratios. The uniaxial isothermal lifetimes coincide very well with literature data. A conservative lifetime description for thermo-mechanical in-Phase and out-of-Phase fatigue test was set based on the isothermal tests at the upper temperature. The comparison of lifetimes from uniaxial and biaxial-planar tests shows that the equivalent strain hypothesis according to von Mises correlates the fatigue lives of the different stress states within a scatter band of two. The failure mechanism including crack initiation, crack growth and the macroscopic crack path were studied by scanning electron microscopy. A change from a mainly transgranular crack growth at 673 K to a mostly intergranular fracture at 923 K as well as under thermo-mechanical fatigue Loading was found. The fatigue lives of the isothermal and thermo-mechanical tests under both uniaxial and biaxial-planar Loading were correlated by a new lifetime model which is based on a stress–strain approach.
Uwe Gampe - One of the best experts on this subject based on the ideXlab platform.
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investigation of isothermal and thermo mechanical fatigue behavior of the nickel base superalloy in738lc using standardized and advanced test methods
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2016Co-Authors: D Hollander, D Kulawinski, S Henkel, Horst Biermann, Marcus Thiele, C Damm, Uwe GampeAbstract:Abstract The uniaxial and biaxial-planar isothermal fatigue behavior as well as the uniaxial thermo-mechanical fatigue behavior of the nickel-base superalloy IN738LC was investigated at high temperatures using standardized and advanced test technologies. Small scale specimens’ tests were carried out in order to study the specimen size effect and biaxial-planar tests under equibiaxial and shear Loading to investigate the influence of the multiaxial stress state on the isothermal fatigue behavior both at 750 °C. Standardized specimens were used to determine the uniaxial isothermal and thermo-mechanical fatigue behavior under in-Phase and out-of-Phase Loading in the temperature range between 750 °C and 950 °C. The standard specimens’ results particularly served as reference data as well as for the verification of a recently developed lifetime prediction model for thermo-mechanical fatigue Loading. The small scale specimens’ results were in good agreement with standardized specimens. The comparison of fatigue lifetimes of uniaxial and biaxial-planar tests showed that the equivalent strain hypothesis according to von Mises is applicable to correlate the fatigue life of the equibiaxial Loading case within a scatter band of factor two, whereas the shear Loading case was predicted conservatively. Furthermore, the recently developed lifetime prediction model correlated the fatigue lives of the isothermal and thermo-mechanical tests under uniaxial and biaxial-planar Loading as well as literature data. Finally, the deformation and crack growth mechanism were studied.