Effect of Overloads and Underloads on Fatigue Crack Growth and Interaction Effects PDF Download
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Author: F. Romeiro
Publisher:
ISBN:
Category : Materials
Languages : en
Pages : 15
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Book Description
Under constant amplitude loading, a single variable (?K) is required in crack growth relationships. The transferability of fatigue laws, determined under constant amplitude loading, to variable amplitude fatigue requires at least an additional variable, whose evolution with crack length accounts for the interaction effects between cycles of different types. The crack opening level (Kop) is usually employed for this purpose because it can be determined from the experiments and compared with predictions from models or FEM analyses. This paper presents an analysis of fatigue crack growth on M(T) specimens of medium carbon steel specimens and using FEM analyses. The specimens are subjected to repeated blocks of cycles made up of one or several overloads separated by a variable number of baseline cycles. The experiments are simulated by FEM analyses, taking into account the cyclic plastic behavior of the low carbon steel. The main objective of this study is to better understand the mechanisms at the origin of interactions effects due to the presence of overloads (or underloads) at different locations of the block loading. It is concluded that the interaction effects are closely related to the cyclic plastic behavior of the material and namely to the Bauschinger effect.
Author: F. Romeiro
Publisher:
ISBN:
Category : Materials
Languages : en
Pages : 15
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Book Description
Under constant amplitude loading, a single variable (?K) is required in crack growth relationships. The transferability of fatigue laws, determined under constant amplitude loading, to variable amplitude fatigue requires at least an additional variable, whose evolution with crack length accounts for the interaction effects between cycles of different types. The crack opening level (Kop) is usually employed for this purpose because it can be determined from the experiments and compared with predictions from models or FEM analyses. This paper presents an analysis of fatigue crack growth on M(T) specimens of medium carbon steel specimens and using FEM analyses. The specimens are subjected to repeated blocks of cycles made up of one or several overloads separated by a variable number of baseline cycles. The experiments are simulated by FEM analyses, taking into account the cyclic plastic behavior of the low carbon steel. The main objective of this study is to better understand the mechanisms at the origin of interactions effects due to the presence of overloads (or underloads) at different locations of the block loading. It is concluded that the interaction effects are closely related to the cyclic plastic behavior of the material and namely to the Bauschinger effect.
Author: Stoyan Ivanov Stoychev
Publisher:
ISBN:
Category : Fracture mechanics
Languages : en
Pages : 498
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Book Description
Author:
Publisher: ASTM International
ISBN:
Category : Alloys
Languages : en
Pages : 362
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Book Description
Author: Peter C. McKeighan
Publisher: ASTM International
ISBN: 0803134797
Category : Aluminum alloys
Languages : en
Pages : 588
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Book Description
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 585
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Book Description
The effects of single overload-underload interaction on constant amplitude crack growth in 2219-T851 aluminum alloy are characterized in terms of delay cycles, affected zone sizes and overload shut-off ratios. Data are presented showing the effects of overload-underload/underload-overload sequences, overload magnitude, underload magnitude, and the constant amplitude maximum and minimum. The effects of hold periods in both tension and compression are also experimentally investigated. Delay cycle data are correlated with predictions from three different crack growth retardation models; namely the generalized Wheeler model, the generalized Willenborg model and the Grumman closure model. For each model, predictions are made using an assumed plastic zone radius and diameter for both plane stress and plane strain conditions and model comparisons are made. Correlations of measured affected zone sizes with the four different assumed plastic zone sizes are also presented. Sensitivities of the generalized Wheeler and generalized Willenborg models to overload shut- off ratio and threshold stress intensity factor are determined. Prediction sensitivity to three different crack growth equations for the 2219-T851 aluminum alloy is also evaluated. Recommendations for future work in development of crack growth retardation models are presented.
Author: D. F. Bryan
Publisher: ASTM International
ISBN: 9780803107205
Category : Technology & Engineering
Languages : en
Pages : 256
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Book Description
Author: W. M. McGee
Publisher:
ISBN:
Category : Mathematical models
Languages : en
Pages : 588
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Book Description
The effects of single overload-underload interaction on constant amplitude crack growth in 2219-T851 aluminum alloy are characterized in terms of delay cycles, affected zone sizes and overload shut-off ratios. Data are presented showing the effects of overload-underload/underload-overload sequences, overload magnitude, underload magnitude, and the constant amplitude maximum and minimum. The effects of hold periods in both tension and compression are also experimentally investigated. Delay cycle data are correlated with predictions from three different crack growth retardation models; namely the generalized Wheeler model, the generalized Willenborg model and the Grumman closure model. For each model, predictions are made using an assumed plastic zone radius and diameter for both plane stress and plane strain conditions and model comparisons are made. Correlations of measured affected zone sizes with the four different assumed plastic zone sizes are also presented. Sensitivities of the generalized Wheeler and generalized Willenborg models to overload shut- off ratio and threshold stress intensity factor are determined. Prediction sensitivity to three different crack growth equations for the 2219-T851 aluminum alloy is also evaluated. Recommendations for future work in development of crack growth retardation models are presented.
Author: W. M. McGee
Publisher:
ISBN:
Category : Mathematical models
Languages : en
Pages : 125
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Book Description
The effects of single overload-underload interaction on constant amplitude crack growth in 2219-T851 aluminum alloy are characterized in terms of delay cycles, affected zone sizes and overload shut-off ratios. Data are presented showing the effects of overload-underload/underload-overload sequences, overload magnitude, underload magnitude, and the constant amplitude maximum and minimum. The effects of hold periods in both tension and compression are also experimentally investigated. Delay cycle data are correlated with predictions from three different crack growth retardation models; namely the generalized Wheeler model, the generalized Willenborg model and the Grumman closure model. For each model, predictions are made using an assumed plastic zone radius and diameter for both plane stress and plane strain conditions and model comparisons are made. Correlations of measured affected zone sizes with the four different assumed plastic zone sizes are also presented. Sensitivities of the generalized Wheeler and generalized Willenborg models to overload shut- off ratio and threshold stress intensity factor are determined. Prediction sensitivity to three different crack growth equations for the 2219-T851 aluminum alloy is also evaluated. Recommendations for future work in development of crack growth retardation models are presented.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 119
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Book Description
A systematic investigation has been carried out on the mechanisms of the retardation in fatigue crack propagation following either a single overload or a large number of multiple overloads. The results from A1 alloy 6061-T6 and 9Cr-2Mo steel confirmed the observation by Paris and Hermann that during the period of retarded fatigue crack growth subsequent to the application of a single overload, two instead of only one crack opening levels exist.
Author: Hans Albert Richard
Publisher: Springer
ISBN: 3319325345
Category : Technology & Engineering
Languages : en
Pages : 305
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Book Description
This book offers a concise introduction to fatigue crack growth, based on practical examples. It discusses the essential concepts of fracture mechanics, fatigue crack growth under constant and variable amplitude loading and the determination of the fracture-mechanical material parameters. The book also introduces the analytical and numerical simulation of fatigue crack growth as well as crack initiation. It concludes with a detailed description of several practical case studies and some exercises. The target group includes graduate students, researchers at universities and practicing engineers.
