The Experts below are selected from a list of 28584 Experts worldwide ranked by ideXlab platform
Huang Yuan - One of the best experts on this subject based on the ideXlab platform.
-
assessment of low cycle Fatigue Crack Growth under mixed mode loading conditions by using a cohesive zone model
International Journal of Fatigue, 2015Co-Authors: Huang YuanAbstract:Abstract Most cohesive zone models were used to reproduce Fatigue Crack Growth under small scale yielding and failed to predict elastic–plastic Fatigue Crack Growth. In the present work a new cohesive zone model is introduced to give a uniform description of both Fatigue Crack Growth and elastoplastic rupture. Damage accumulation of the cohesive model contains both monotonic damage as well as cyclic damage and validated by corresponding mixed-mode fracture and Fatigue experiments of an austenitic stainless steel. Computations confirm that the present cohesive zone model may provide a uniform description for the whole Fatigue Crack Growth regimes.
G Glinka - One of the best experts on this subject based on the ideXlab platform.
-
analysis of Fatigue Crack Growth under spectrum loading the unigrow Fatigue Crack Growth model
Theoretical and Applied Fracture Mechanics, 2015Co-Authors: S Mikheevskiy, S Bogdanov, G GlinkaAbstract:Abstract The Fatigue process near notches and Cracks is governed by highly concentrated strains and stresses in the notch/Crack tip region. Therefore, the Fatigue Crack Growth can be subsequently considered as a process of successive Crack increments resulting from material damage occurring in this region. The assumption mentioned above was used in order to model the Fatigue Crack Growth based on the analysis of elastic–plastic Crack tip stresses and strains. The Fatigue Crack Growth was predicted by simulating the stress–strain response in the material volume adjacent to the Crack tip and estimating the accumulated Fatigue damage in a manner similar to Fatigue analyses of stationary notches. The Fatigue Crack Growth was regarded as a process of successive Crack re-initiations in the Crack tip region. The Fatigue Crack Growth driving force was derived on the basis of the local stresses and strains at the Crack tip using the Smith–Watson–Topper (SWT) Fatigue damage parameter: D = σmax⋅Δe/2. It was found that the Fatigue Crack Growth was controlled by a two parameter driving force derived in the form of power law expression Δκ = ΔK1−pKpmax. The two parameter driving force enabled to predict the effect of the mean stress on the Fatigue Crack Growth rate including the influence of the applied compressive stress and tensile overloads, the overload effect and the effect of the Crack tip internal (residual) stress resulted from the reversed cyclic plasticity. Experimental Fatigue Crack Growth data set obtained for the aluminum alloy (2324 T7) was used for the verification of the methodology. The method can also be used to predict Fatigue lives of notched and welded components where both stages of the Fatigue process called as the Fatigue Crack initiation and propagation are important.
-
Fatigue Crack Growth analysis of structural components the unigrow two parameter driving force model
ICMFF9, 2013Co-Authors: S Mikheevskiy, G Glinka, D. AlgeraAbstract:A generalised step-by-step procedure for Fatigue Crack Growth analysis of structural components subjected to variable amplitude loading spectra has been presented. The method has been illustrated by analysing Fatigue Growth of a planar corner Crack in an attachment lug made of Al7050-T7451 alloy. Stress intensity factors required for the Fatigue Crack Growth analysis were calculated using the weight function method. In addition, so-called “load-shedding” effect was accounted for in order to determine appropriate magnitudes of the applied stress intensity factors. The rate of the load shedding was determined with the help of the FE method by funding the amount of the load transferred through the Cracked ligament. The UniGrow Fatigue Crack Growth model, based on the analysis the material stress-strain behaviour near the Crack tip, has been used to simulate the Fatigue Crack Growth under three variable amplitude loading spectra. The comparison between theoretical estimations and experimental data proved the ability of the UniGrow model to correctly predict Fatigue Crack Growth behaviour of two-dimensional planar Cracks under complex stress field and subjected to arbitrary variable amplitude loading. BASICS OF THE UNIGROW Fatigue Crack Growth MODEL The UniGrow Fatigue Crack Growth model, proposed by Noroozi and Glinka [1], is based on the idea that the Fatigue process near Cracks and notches is governed by highly concentrated strains and stresses in the notch/Crack tip region. Therefore, the Fatigue Crack Growth can be subsequently considered as a process of successive Crack increments resulting from material damage in the tip region. In addition the two parameter driving force postulated by Vasudevan et.al [2] was also incorporated. It was postulated that the real material can be modeled as a set of elementary particles or material blocks of a finite dimension, ρ*. The assumption of the elementary material block implies that the actual stress-strain and Fatigue response of the material near the Crack tip is such as the Crack had a blunt tip with the radius of ρ*. Therefore, the usual notch stress-strain analysis techniques can by applied in order to determine
-
Fatigue Crack Growth analysis under spectrum loading in various environmental conditions
Metallurgical and Materials Transactions A-physical Metallurgy and Materials Science, 2013Co-Authors: S Mikheevskiy, G Glinka, E LeeAbstract:The Fatigue process consists, from the engineering point of view, of three stages: Crack initiation, Fatigue Crack Growth, and the final failure. It is also known that the Fatigue process near notches and Cracks is governed by local strains and stresses in the regions of maximum stress and strain concentrations. Therefore, the Fatigue Crack Growth can be considered as a process of successive Crack increments, and the Fatigue Crack initiation and subsequent Growth can be modeled as one repetitive process. The assumptions mentioned above were used to derive a Fatigue Crack Growth model based, called later as the UniGrow model, on the analysis of cyclic elastic–plastic stresses–strains near the Crack tip. The Fatigue Crack Growth rate was determined by simulating the cyclic stress–strain response in the material volume adjacent to the Crack tip and calculating the accumulated Fatigue damage in a manner similar to Fatigue analysis of stationary notches. The Fatigue Crack Growth driving force was derived on the basis of the stress and strain history at the Crack tip and the Smith–Watson–Topper (SWT) Fatigue damage parameter, D = σmaxΔe/2. It was subsequently found that the Fatigue Crack Growth was controlled by a two-parameter driving force in the form of a weighted product of the stress intensity range and the maximum stress intensity factor, ΔKpKmax1−p. The effect of the internal (residual) stress induced by the reversed cyclic plasticity has been accounted for and therefore the two-parameter driving force made it possible to predict the effect of the mean stress including the influence of the applied compressive stress, tensile overloads, and variable amplitude spectrum loading. It allows estimating the Fatigue life under variable amplitude loading without using Crack closure concepts. Several experimental Fatigue Crack Growth datasets obtained for the Al 7075 aluminum alloy were used for the verification of the proposed unified Fatigue Crack Growth model. The method can be also used to predict Fatigue Crack Growth under constant amplitude and spectrum loading in various environmental conditions such as vacuum, air, and corrosive environment providing that appropriate limited constant amplitude Fatigue Crack Growth data obtained in the same environment are available. The proposed methodology is equally suitable for Fatigue analysis of smooth, notched, and Cracked components.
-
Analysis of Fatigue Crack Growth in an attachment lug based on the weight function technique and the UniGrow Fatigue Crack Growth model
International Journal of Fatigue, 2012Co-Authors: S Mikheevskiy, G Glinka, D. AlgeraAbstract:Abstract A generalised step-by-step procedure for Fatigue Crack Growth analysis of structural components subjected to variable amplitude loading spectra has been presented. The method has been illustrated by analysing Fatigue Growth of planar corner Crack in an attachment lug made of Al7050-T7451 alloy. Stress intensity factors required for the Fatigue Crack Growth analysis were calculated using the weight function method. In addition, so-called “load-shedding” effect was accounted for in order to determine appropriate magnitudes of the applied stress intensity factors. The rate of the load shedding was determined with the help of the finite element (FE) method by finding the amount of the load transferred through the Cracked ligament. The UniGrow Fatigue Crack Growth model, based on the material stress–strain behaviour near the Crack tip, has been used to simulate the Fatigue Crack Growth under two variable amplitude loading spectra. The comparison between theoretical predictions and experimental data proved the ability of the UniGrow model to correctly predict Fatigue Crack Growth behaviour of two-dimensional planar Cracks under complex stress field and subjected to arbitrary variable amplitude loading.
-
elastic plastic Fatigue Crack Growth analysis under variable amplitude loading spectra
International Journal of Fatigue, 2009Co-Authors: S Mikheevskiy, G GlinkaAbstract:Most Fatigue loaded components or structures experience a variety of stress histories under typical operating loading conditions. In the case of constant amplitude loading the Fatigue Crack Growth depends only on the component geometry, applied loading and material properties. In the case of variable amplitude loading the Fatigue Crack Growth depends also on the preceding cyclic loading history. Various load sequences may induce different load-interaction effects which can cause either acceleration or deceleration of Fatigue Crack Growth. The recently modified two-parameter Fatigue Crack Growth model based on the local stress–strain material behaviour at the Crack tip [1,2] was used to account for the variable amplitude loading effects. The experimental verification of the proposed model was performed using 7075-T6 aluminum alloy, Ti-17 titanium alloy, and 350WT steel. The good agreement between theoretical and experimental data shows the ability of the model to predict the Fatigue life under different types of variable amplitude loading spectra.
S Mikheevskiy - One of the best experts on this subject based on the ideXlab platform.
-
analysis of Fatigue Crack Growth under spectrum loading the unigrow Fatigue Crack Growth model
Theoretical and Applied Fracture Mechanics, 2015Co-Authors: S Mikheevskiy, S Bogdanov, G GlinkaAbstract:Abstract The Fatigue process near notches and Cracks is governed by highly concentrated strains and stresses in the notch/Crack tip region. Therefore, the Fatigue Crack Growth can be subsequently considered as a process of successive Crack increments resulting from material damage occurring in this region. The assumption mentioned above was used in order to model the Fatigue Crack Growth based on the analysis of elastic–plastic Crack tip stresses and strains. The Fatigue Crack Growth was predicted by simulating the stress–strain response in the material volume adjacent to the Crack tip and estimating the accumulated Fatigue damage in a manner similar to Fatigue analyses of stationary notches. The Fatigue Crack Growth was regarded as a process of successive Crack re-initiations in the Crack tip region. The Fatigue Crack Growth driving force was derived on the basis of the local stresses and strains at the Crack tip using the Smith–Watson–Topper (SWT) Fatigue damage parameter: D = σmax⋅Δe/2. It was found that the Fatigue Crack Growth was controlled by a two parameter driving force derived in the form of power law expression Δκ = ΔK1−pKpmax. The two parameter driving force enabled to predict the effect of the mean stress on the Fatigue Crack Growth rate including the influence of the applied compressive stress and tensile overloads, the overload effect and the effect of the Crack tip internal (residual) stress resulted from the reversed cyclic plasticity. Experimental Fatigue Crack Growth data set obtained for the aluminum alloy (2324 T7) was used for the verification of the methodology. The method can also be used to predict Fatigue lives of notched and welded components where both stages of the Fatigue process called as the Fatigue Crack initiation and propagation are important.
-
Fatigue Crack Growth analysis of structural components the unigrow two parameter driving force model
ICMFF9, 2013Co-Authors: S Mikheevskiy, G Glinka, D. AlgeraAbstract:A generalised step-by-step procedure for Fatigue Crack Growth analysis of structural components subjected to variable amplitude loading spectra has been presented. The method has been illustrated by analysing Fatigue Growth of a planar corner Crack in an attachment lug made of Al7050-T7451 alloy. Stress intensity factors required for the Fatigue Crack Growth analysis were calculated using the weight function method. In addition, so-called “load-shedding” effect was accounted for in order to determine appropriate magnitudes of the applied stress intensity factors. The rate of the load shedding was determined with the help of the FE method by funding the amount of the load transferred through the Cracked ligament. The UniGrow Fatigue Crack Growth model, based on the analysis the material stress-strain behaviour near the Crack tip, has been used to simulate the Fatigue Crack Growth under three variable amplitude loading spectra. The comparison between theoretical estimations and experimental data proved the ability of the UniGrow model to correctly predict Fatigue Crack Growth behaviour of two-dimensional planar Cracks under complex stress field and subjected to arbitrary variable amplitude loading. BASICS OF THE UNIGROW Fatigue Crack Growth MODEL The UniGrow Fatigue Crack Growth model, proposed by Noroozi and Glinka [1], is based on the idea that the Fatigue process near Cracks and notches is governed by highly concentrated strains and stresses in the notch/Crack tip region. Therefore, the Fatigue Crack Growth can be subsequently considered as a process of successive Crack increments resulting from material damage in the tip region. In addition the two parameter driving force postulated by Vasudevan et.al [2] was also incorporated. It was postulated that the real material can be modeled as a set of elementary particles or material blocks of a finite dimension, ρ*. The assumption of the elementary material block implies that the actual stress-strain and Fatigue response of the material near the Crack tip is such as the Crack had a blunt tip with the radius of ρ*. Therefore, the usual notch stress-strain analysis techniques can by applied in order to determine
-
Fatigue Crack Growth analysis under spectrum loading in various environmental conditions
Metallurgical and Materials Transactions A-physical Metallurgy and Materials Science, 2013Co-Authors: S Mikheevskiy, G Glinka, E LeeAbstract:The Fatigue process consists, from the engineering point of view, of three stages: Crack initiation, Fatigue Crack Growth, and the final failure. It is also known that the Fatigue process near notches and Cracks is governed by local strains and stresses in the regions of maximum stress and strain concentrations. Therefore, the Fatigue Crack Growth can be considered as a process of successive Crack increments, and the Fatigue Crack initiation and subsequent Growth can be modeled as one repetitive process. The assumptions mentioned above were used to derive a Fatigue Crack Growth model based, called later as the UniGrow model, on the analysis of cyclic elastic–plastic stresses–strains near the Crack tip. The Fatigue Crack Growth rate was determined by simulating the cyclic stress–strain response in the material volume adjacent to the Crack tip and calculating the accumulated Fatigue damage in a manner similar to Fatigue analysis of stationary notches. The Fatigue Crack Growth driving force was derived on the basis of the stress and strain history at the Crack tip and the Smith–Watson–Topper (SWT) Fatigue damage parameter, D = σmaxΔe/2. It was subsequently found that the Fatigue Crack Growth was controlled by a two-parameter driving force in the form of a weighted product of the stress intensity range and the maximum stress intensity factor, ΔKpKmax1−p. The effect of the internal (residual) stress induced by the reversed cyclic plasticity has been accounted for and therefore the two-parameter driving force made it possible to predict the effect of the mean stress including the influence of the applied compressive stress, tensile overloads, and variable amplitude spectrum loading. It allows estimating the Fatigue life under variable amplitude loading without using Crack closure concepts. Several experimental Fatigue Crack Growth datasets obtained for the Al 7075 aluminum alloy were used for the verification of the proposed unified Fatigue Crack Growth model. The method can be also used to predict Fatigue Crack Growth under constant amplitude and spectrum loading in various environmental conditions such as vacuum, air, and corrosive environment providing that appropriate limited constant amplitude Fatigue Crack Growth data obtained in the same environment are available. The proposed methodology is equally suitable for Fatigue analysis of smooth, notched, and Cracked components.
-
Analysis of Fatigue Crack Growth in an attachment lug based on the weight function technique and the UniGrow Fatigue Crack Growth model
International Journal of Fatigue, 2012Co-Authors: S Mikheevskiy, G Glinka, D. AlgeraAbstract:Abstract A generalised step-by-step procedure for Fatigue Crack Growth analysis of structural components subjected to variable amplitude loading spectra has been presented. The method has been illustrated by analysing Fatigue Growth of planar corner Crack in an attachment lug made of Al7050-T7451 alloy. Stress intensity factors required for the Fatigue Crack Growth analysis were calculated using the weight function method. In addition, so-called “load-shedding” effect was accounted for in order to determine appropriate magnitudes of the applied stress intensity factors. The rate of the load shedding was determined with the help of the finite element (FE) method by finding the amount of the load transferred through the Cracked ligament. The UniGrow Fatigue Crack Growth model, based on the material stress–strain behaviour near the Crack tip, has been used to simulate the Fatigue Crack Growth under two variable amplitude loading spectra. The comparison between theoretical predictions and experimental data proved the ability of the UniGrow model to correctly predict Fatigue Crack Growth behaviour of two-dimensional planar Cracks under complex stress field and subjected to arbitrary variable amplitude loading.
-
elastic plastic Fatigue Crack Growth analysis under variable amplitude loading spectra
International Journal of Fatigue, 2009Co-Authors: S Mikheevskiy, G GlinkaAbstract:Most Fatigue loaded components or structures experience a variety of stress histories under typical operating loading conditions. In the case of constant amplitude loading the Fatigue Crack Growth depends only on the component geometry, applied loading and material properties. In the case of variable amplitude loading the Fatigue Crack Growth depends also on the preceding cyclic loading history. Various load sequences may induce different load-interaction effects which can cause either acceleration or deceleration of Fatigue Crack Growth. The recently modified two-parameter Fatigue Crack Growth model based on the local stress–strain material behaviour at the Crack tip [1,2] was used to account for the variable amplitude loading effects. The experimental verification of the proposed model was performed using 7075-T6 aluminum alloy, Ti-17 titanium alloy, and 350WT steel. The good agreement between theoretical and experimental data shows the ability of the model to predict the Fatigue life under different types of variable amplitude loading spectra.
Thomas Siegmund - One of the best experts on this subject based on the ideXlab platform.
-
numerical simulation of constraint effects in Fatigue Crack Growth
International Journal of Fatigue, 2005Co-Authors: B Wang, Thomas SiegmundAbstract:Abstract The computational analysis of constraint effects on Fatigue Crack Growth is discussed. An irreversible cohesive zone model is used in the computations to describe the processes of material separation under cyclic loading. This approach is promising for the investigation of Fatigue Crack Growth under constraint as the energy dissipation due to the formation of new Crack surface and cyclic plastic deformation is accounted for independently. Fatigue Crack Growth in multi-layer structures under consideration of different levels of T -stress are conducted with a modified boundary layer model. Fatigue Crack Growth is computed as a function of layer thickness and T -stress for constant and variable amplitude loading cases.
-
a numerical study of transient Fatigue Crack Growth by use of an irreversible cohesive zone model
International Journal of Fatigue, 2004Co-Authors: Thomas SiegmundAbstract:Abstract Transient Fatigue Crack Growth is studied for a material system in which the Crack tip is shielded due to Crack bridging. The process of material separation during Fatigue Crack Growth is described by the use of an irreversible cohesive zone model. In contrast to past developments of cohesive zone models, the traction–separation behavior does not follow a predefined path, but is dependent on the evolution of the damage dependent cohesive zone properties. The model definition is given and the basic uniaxial response of the model documented. The cohesive zone model is subsequently applied in a numerical study of transient Fatigue Crack Growth. Single overload cases are computed to demonstrate the effects of variations in the cohesive zone properties. Block loading sequences with variations in the amplitude and the load ratio are computed. Model predictions qualitatively compare well to experimentally observed effects of Fatigue Crack Growth transients in materials with Crack bridging zones.
Royce Forman - One of the best experts on this subject based on the ideXlab platform.
-
laser and shot peening effects on Fatigue Crack Growth in friction stir welded 7075 t7351 aluminum alloy joints
International Journal of Fatigue, 2007Co-Authors: Omar Hatamleh, Jed Lyons, Royce FormanAbstract:The influence of shot and laser peening on the Fatigue Crack Growth behavior of friction stir welded (FSW) aluminum alloy (AA) 7075-T7351 sheets was investigated. The alterations resulting from this surface modification on the Fatigue Crack Growth of FSW were characterized and evaluated for two different Crack configurations. A systematic investigation of the various peening effects indicated a significant decrease in Fatigue Crack Growth rates resulting from using laser peening compared with native welded and unwelded specimens. In contrast, shot peened specimens did not result in a significant reduction in Fatigue Crack Growth. The Fatigue striation spacings for the laser peened specimens were assessed and found to be small compared with the unpeened, and shot peened specimens. The reduction in striation spacing indicates a slower Fatigue Crack Growth rate and is partially attributed to the deeper compressive residual stresses induced by the laser peening.
-
on generating Fatigue Crack Growth thresholds
International Journal of Fatigue, 2003Co-Authors: S C Forth, J C Newman, Royce FormanAbstract:The Fatigue Crack Growth threshold, defining Crack Growth as either very slow or nonexistent, has been traditionally determined with standardized load reduction methodologies. These experimental procedures can induce load history effects that result in Crack closure. This history can affect the Crack driving force, i.e. during the unloading process the Crack will close first at some point along the wake or blunt at the Crack tip, reducing the effective load at the Crack tip. One way to reduce the effects of load history is to propagate a Crack under constant amplitude loading. As a Crack propagates under constant amplitude loading, the stress intensity factor range, Delta K, will increase, as will the Crack Growth rate. da/dN. A Fatigue Crack Growth threshold test procedure is experimentally validated that does not produce load history effects and can be conducted at a specified stress ratio, R. The authors have chosen to study a ductile aluminum alloy where the plastic deformations generated during testing may be of the magnitude to impact the Crack opening.
