The Experts below are selected from a list of 46755 Experts worldwide ranked by ideXlab platform
T.s. Lam - One of the best experts on this subject based on the ideXlab platform.
-
effective strain fatigue Life data for variable amplitude fatigue
International Journal of Fatigue, 1997Co-Authors: T.h. Topper, T.s. LamAbstract:Abstract The usual analysis procedure for variable amplitude fatigue calculates fatigue damage based on constant amplitude strain controlled fatigue tests of smooth specimens. The resulting predictions are typically nonconservative due to a load interaction effect in variable amplitude fatigue. This paper reviews recent work which shows that large loads in a service load history decrease the crack opening stress and as a result increase the effective strain range for subsequent small cycles. A new strain–Life fatigue test is introduced in which periodic large strain cycles reduce the crack opening stress for subsequent smaller cycles. The overloads are applied frequently enough that closure free fully open crack growth is achieved for the small cycles in the long Life regime. An effective strain–Life Curve is derived and a crack opening stress equation calibrated by comparison of constant amplitude and effective strain ranges at given fatigue lives. The use of the effective strain–Life Curve in predicting fatigue lives is illustrated for service strain histories and for a variable amplitude load sequence applied to notched specimens. The predictions are good but somewhat conservative.
-
Effective strain–fatigue Life data for variable amplitude fatigue
International Journal of Fatigue, 1997Co-Authors: T.h. Topper, T.s. LamAbstract:Abstract The usual analysis procedure for variable amplitude fatigue calculates fatigue damage based on constant amplitude strain controlled fatigue tests of smooth specimens. The resulting predictions are typically nonconservative due to a load interaction effect in variable amplitude fatigue. This paper reviews recent work which shows that large loads in a service load history decrease the crack opening stress and as a result increase the effective strain range for subsequent small cycles. A new strain–Life fatigue test is introduced in which periodic large strain cycles reduce the crack opening stress for subsequent smaller cycles. The overloads are applied frequently enough that closure free fully open crack growth is achieved for the small cycles in the long Life regime. An effective strain–Life Curve is derived and a crack opening stress equation calibrated by comparison of constant amplitude and effective strain ranges at given fatigue lives. The use of the effective strain–Life Curve in predicting fatigue lives is illustrated for service strain histories and for a variable amplitude load sequence applied to notched specimens. The predictions are good but somewhat conservative.
T.h. Topper - One of the best experts on this subject based on the ideXlab platform.
-
Effective Strain-Fatigue Life of Dual Phase 590 Steel
2013Co-Authors: M. El-zeghayar, T.h. Topper, J. Bonnen, R. SohmshettyAbstract:Dual phase 590 steel belongs to the family of advanced high strength steels (AHSS) that has gained popularity in the automotive industry as lightweight vehicle components. An experimental study on dual phase (DP) 590 as-received steel was conducted to study the effect of variable amplitude loading on the fatigue Life and construct the effective strain-Life Curve for the material. Overloads were applied in the form of large near yield stress cycles that decreased the crack opening stress for the subsequent smaller cycles. An effective strain-Life Curve was derived from constant amplitude and overload tests, and a crack opening stress equation was calibrated by a comparison of constant amplitude and effective strain ranges at given fatigue lives. It was also noticed that the material even at a Life of 107 cycles exhibited significant plastic strain amplitudes that deviated from the single slope behavior of a Coffin-Manson equation.
-
effective strain fatigue Life data for variable amplitude fatigue
International Journal of Fatigue, 1997Co-Authors: T.h. Topper, T.s. LamAbstract:Abstract The usual analysis procedure for variable amplitude fatigue calculates fatigue damage based on constant amplitude strain controlled fatigue tests of smooth specimens. The resulting predictions are typically nonconservative due to a load interaction effect in variable amplitude fatigue. This paper reviews recent work which shows that large loads in a service load history decrease the crack opening stress and as a result increase the effective strain range for subsequent small cycles. A new strain–Life fatigue test is introduced in which periodic large strain cycles reduce the crack opening stress for subsequent smaller cycles. The overloads are applied frequently enough that closure free fully open crack growth is achieved for the small cycles in the long Life regime. An effective strain–Life Curve is derived and a crack opening stress equation calibrated by comparison of constant amplitude and effective strain ranges at given fatigue lives. The use of the effective strain–Life Curve in predicting fatigue lives is illustrated for service strain histories and for a variable amplitude load sequence applied to notched specimens. The predictions are good but somewhat conservative.
-
Effective strain–fatigue Life data for variable amplitude fatigue
International Journal of Fatigue, 1997Co-Authors: T.h. Topper, T.s. LamAbstract:Abstract The usual analysis procedure for variable amplitude fatigue calculates fatigue damage based on constant amplitude strain controlled fatigue tests of smooth specimens. The resulting predictions are typically nonconservative due to a load interaction effect in variable amplitude fatigue. This paper reviews recent work which shows that large loads in a service load history decrease the crack opening stress and as a result increase the effective strain range for subsequent small cycles. A new strain–Life fatigue test is introduced in which periodic large strain cycles reduce the crack opening stress for subsequent smaller cycles. The overloads are applied frequently enough that closure free fully open crack growth is achieved for the small cycles in the long Life regime. An effective strain–Life Curve is derived and a crack opening stress equation calibrated by comparison of constant amplitude and effective strain ranges at given fatigue lives. The use of the effective strain–Life Curve in predicting fatigue lives is illustrated for service strain histories and for a variable amplitude load sequence applied to notched specimens. The predictions are good but somewhat conservative.
-
THE EFFECTIVE STRESS RANGE AS A FATIGUE DAMAGE PARAMETER
The Rainflow Method in Fatigue, 1992Co-Authors: D.l. Duquesnay, T.h. Topper, M.a. Pompetzki, R. JurcevicAbstract:This paper shows that the changes in crack closure and the associated effective stress range induced by mean stresses and overloads are responsible for the accompanying changes in damage accumulation rates and fatigue limits. When crack closure effects are accounted for, fatigue damage can be calculated using a single effective stress range versus fatigue Life Curve. Experimental evidence to support the effective stress range as a fatigue damage parameter is provided for a 2024-T351 aluminum alloy and a CSA G40.21 structural steel.
Guan Deqing - One of the best experts on this subject based on the ideXlab platform.
-
The fatigue Life Curve prediction model for welded steel structures based on local method
Fourth International Conference on Advances in Steel Structures, 2005Co-Authors: Guan Deqing, Zhao XiaohuaAbstract:Publisher Summary The chapter discusses the fatigue Life Curve prediction model for welded steel structures based on a local method. It considers the effects of the material properties, geometric form, residual stress, and cyclic-stress ratio of welded steel structures on the fatigue Life. Based on the fatigue Life Curves of smooth specimens and the property of the fatigue Life Curves of welded steel structures, by adopting the three-finite element analysis and the area method model, an estimation method of the fatigue Life Curve for welded steel structures is set up in the chapter. As an example of application of the method, the fatigue Life Curves of four groups of misaligned welded joints, “T” type of welded joint, and cruciform joint are predicted in the chapter. Good agreement between the predicating and experimental results is achieved in the chapter. Adopting the method in this dissertation to obtain S-N Curve of welded steel structures can reduce fatigue experiments and be helpful in gaining economic efficiency.
-
A method to estimate P-S-N Curve of welded joints under general stress ratio
Advances in Steel Structures (ICASS '02), 2002Co-Authors: Guan Deqing, Yi WeijianAbstract:Publisher Summary This chapter takes account of the effects of material properties, type of loading, geometric shape, stress ratio, and residual stress in notch root of welded joints on the fatigue strength respectively. By means of the concept of the worst-case notch and an estimating formula of effective stress concentration factor, based on two groups of the fatigue experimental results under high stress level, the chapter presents a predicting method of the fatigue Life Curve with arbitrary survival rate under general stress ratio for welded joints. P-S-N Curves of six types of welded joints under general stress ratio are successfully estimated. A method to predict the fatigue Life Curve with arbitrary survival rate under general stress ratio for welded joints is developed by the chapter.
-
A method of predicting the fatigue Life Curve for misaligned welded joints
International Journal of Fatigue, 1996Co-Authors: Guan DeqingAbstract:The effects of material properties, manner of loading, geometric shape, value of misalignment, residual stress, stress ratio and short crack in notch root of misaligned welded joint on the fatigue Life are considered respectively. By means of Peterson's equation and Topper's equation and the concept of the worst-case fatigue notch factor, two estimating equations of effective stress concentration factors have been adopted. A method for predicting the fatigue Life Curve of misaligned welded joints for middle range of cycle numbers is developed. As an example of application of the method, the fatigue Life Curves of several misaligned welded joints made of low-alloy structural steel are predicted. Good agreement between the predicting and experimental results is achieved. This method has significance for engineering applications.
Stanisław Mroziński - One of the best experts on this subject based on the ideXlab platform.
-
Approximate determination of a strain-controlled fatigue Life Curve for aluminum alloy sheets for aircraft structures☆
International Journal of Fatigue, 2012Co-Authors: Adam Lipski, Stanisław MrozińskiAbstract:Abstract This paper deals with selected methods of approximate determination of a strain-controlled fatigue Life Curve for aluminum alloy sheets used in aircraft structures. Authors based their analysis of those methods on the results of own research of 2024-T3 alloy and its Russian equivalent D16CzATW. The approximate strain-fatigue Life Curves were compared with the experimental Curves. The influence of inconsistencies between those Curves on the calculation results was analyzed on computational examples by means of the Palmgren–Miner’s rule.
Ali Fatemi - One of the best experts on this subject based on the ideXlab platform.
-
Variable amplitude fatigue behavior and Life predictions of case-hardened steels
International Journal of Fatigue, 2010Co-Authors: Fengjie Yin, Ali Fatemi, John Joseph Francis BonnenAbstract:Abstract Fatigue behavior of case-hardened steel specimens were investigated under variable amplitude loading conditions including two-level load tests, periodic overload tests, and service load history tests. Fatigue Life predictions were made using a two-layer model based on case and core material fatigue properties and compared to the experimental results. Both standard strain-Life Curve based on constant amplitude data as well as effective strain-Life Curve based on periodic overload data were used for Life predictions. The effective strain-Life Curve showed that periodic overloads have a strong effect on fatigue Life of case-hardened specimens. In service load history tests with plastic deformation, the fatigue damage caused by the small cycles in the load history is larger than the damage calculated from the standard strain-Life Curve. For periodic overload or variable amplitude service load history, the linear damage rule (LDR) resulted in reasonably good Life predictions, while for high–low step loading tests the damage Curve approach (DCA) resulted in better predictions.
-
strain controlled fatigue properties of steels and some simple approximations
International Journal of Fatigue, 2000Co-Authors: M L Roessle, Ali FatemiAbstract:Abstract In this study, first strain-controlled deformation and fatigue data are reported and compared for several steels most commonly used in the ground vehicle industry. Correlations between monotonic tensile data and constant amplitude strain-controlled fatigue properties are then investigated, and validity of some of the more commonly used methods of estimating fatigue properties is examined. A simple method requiring only hardness and modulus of elasticity is proposed for estimation of the strain–Life Curve. Prediction capability of this method is evaluated for steels with hardness between 150 and 700 HB and compared with several other methods proposed in the literature. The proposed method is shown to provide good approximations of the strain–Life Curve.
