The Experts below are selected from a list of 2397 Experts worldwide ranked by ideXlab platform

Gang Chen - One of the best experts on this subject based on the ideXlab platform.

  • Biaxial Fatigue crack growth in proton exchange membrane of fuel cells based on cyclic cohesive finite element method
    International Journal of Mechanical Sciences, 2021
    Co-Authors: Yang Wang, Xuyun Guo, Shouwen Shi, G J Weng, Gang Chen
    Abstract:

    Abstract During the operation of proton exchange membrane in fuel cells, cyclic mechanical loads are introduced due to the humidity cycles. The resulting Fatigue crack is known to be the main source for its mechanical degradation. In this paper, we use a relation between damage evolution of the cohesive elements and Paris law to simulate the Biaxial Fatigue crack growth. The effects of various loading conditions are investigated. The predicted crack growth is in a good agreement with experimental studies. Both the transverse stress and the tensile overload have retardation effects. It is also found that the Fatigue crack growth rate associated with a shorter pre-crack depends more on the load waveform. Moreover, Fatigue crack grows faster under the low-high loading history than the high-low one. These simulation results have provided significant insights into the Fatigue failure behavior of membranes during operation conditions and can help improve their durability.

  • Biaxial Fatigue crack propagation behavior of perfluorosulfonic acid membranes
    Journal of Power Sources, 2018
    Co-Authors: Qiang Lin, Shouwen Shi, Lei Wang, Xu Chen, Gang Chen
    Abstract:

    Abstract Perfluorosulfonic-acid membranes have long been used as the typical electrolyte for polymer-electrolyte fuel cells, which not only transport proton and water but also serve as barriers to prevent reactants mixing. However, too often the structural integrity of perfluorosulfonic-acid membranes is impaired by membrane thinning or cracks/pinholes formation induced by mechanical and chemical degradations. Despite the increasing number of studies that report crack formation, such as crack size and shape, the underlying mechanism and driving forces have not been well explored. In this paper, the Fatigue crack propagation behaviors of Nafion membranes subjected to Biaxial loading conditions have been investigated. In particular, the Fatigue crack growth rates of flat cracks in responses to different loading conditions are compared, and the impact of transverse stress on Fatigue crack growth rate is clarified. In addition, the crack paths for slant cracks under both uniaxial and Biaxial loading conditions are discussed, which are similar in geometry to those found after accelerated stress testing of fuel cells. The directions of initial crack propagation are calculated theoretically and compared with experimental observations, which are in good agreement. The findings reported here lays the foundation for understanding of mechanical failure of membranes.

Nam Phan - One of the best experts on this subject based on the ideXlab platform.

  • effects of overload mode mixity on Fatigue damage behavior and governing micromechanisms in aa7075 under Biaxial Fatigue loading
    International Journal of Fatigue, 2021
    Co-Authors: Abhay K. Singh, Aditi Chattopadhyay, Siddhant Datta, Nam Phan
    Abstract:

    Abstract An investigation into the effects of overload mode-mixity on crack growth behavior and governing micromechanisms of AA7075 T6 has been conducted. Cruciform AA7075 T6 specimens were subjected to constant amplitude planar Biaxial Fatigue with single overloads, and key Fatigue damage behavior, including Fatigue life, crack growth rate, and recovery distance, were investigated and correlated to overload parameters. Additionally, SEM fractography was conducted to identify and relate fracture surface features to governing Fatigue damage micromechanisms. An increase in Fatigue life was observed for all cases of mode-mixity, with the minimum increase occurring at 45°. The mix-mode overloads also caused crack retardation in all cases. In the shear dominant overloads, however, initial post-overload crack acceleration occurred and was immediately followed by crack retardation. Microscale analysis showed distinct fracture features in the pre-overload, transient, and post-overload regions for both tensile and shear dominant overloads.

  • Characterization of crack propagation behavior in Al-7075 under in-plane Biaxial Fatigue loading with shear overloads
    International Journal of Fatigue, 2020
    Co-Authors: Abhay K. Singh, Aditi Chattopadhyay, Siddhant Datta, Nam Phan
    Abstract:

    Abstract Effect of shear overloads in an otherwise constant amplitude, tensile Biaxial Fatigue loading is investigated using a cruciform specimen of Al 7075-T651, and the crack propagation behavior and governing micromechanisms are characterized. It was observed that with an increase in shear overload ratio Fatigue life of the specimen is increased and the crack growth rate is significantly affected. This behavior is attributed to the combined effects of competing mechanisms including compressive residual stress, plasticity induced crack closure, and strain hardening. The fractographic study revealed features of shear fracture in the transient region and tensile fracture in the pre-overload region and post-overload region.

  • Fatigue crack propagation under Biaxial Fatigue loading with single overloads
    International Journal of Fatigue, 2018
    Co-Authors: Siddhant Datta, Aditi Chattopadhyay, Nagaraja Iyyer, Nam Phan
    Abstract:

    Abstract The crack propagation behavior and the governing crack growth micromechanisms in aluminum alloy under in-plane Biaxial Fatigue loading with single overloads, of different magnitudes and occurring at different Fatigue crack lengths, is investigated. The microscale fracture mechanisms governing crack growth behavior under these conditions are identified through detailed fractography. Crack growth retardation behavior observed due to the occurrence of single overloads is correlated with overload magnitude, instantaneous Fatigue crack length, crack-tip plasticity and fracture surface morphology. The results obtained provide insight into the relationship between macroscale crack growth behavior to microstructural mechanisms, which is essential to understanding the Fatigue behavior of metallic materials under variable amplitude Biaxial loading scenarios.

Shankar Mall - One of the best experts on this subject based on the ideXlab platform.

  • Crack growth behavior under Biaxial Fatigue with phase difference
    International Journal of Fatigue, 2015
    Co-Authors: Shankar Mall, V.y. Perel
    Abstract:

    Abstract Crack growth behavior of aluminum alloy 7075-T6 was characterized under in-plane Biaxial tension–tension Fatigue with phase differences of 90° or 180° between the two applied orthogonal cyclic loads. The initial single crack, created under the Biaxial Fatigue without any phase difference, splits into two symmetric cracks under the Biaxial Fatigue with the phase difference. The split cracks grow without any further branching. Directions of split cracks deviate sharply from the direction of the initial single crack. Under both phase differences of 90° and 180°, lengths of both split cracks are almost the same at a certain number of cycle. Strain energy release rate versus crack growth rate relationships of the split cracks are almost equal to each other. Further, sum of strain energy release rates at a given crack growth rate of both split cracks is equal to that of a single crack under the Biaxial Fatigue without phase difference. Analytical and finite element analyses are presented to explain the splitting of a crack due to the phase difference between the applied Biaxial cyclic loads.

  • Biaxial tension tension Fatigue crack growth behavior of 2024 t3 under ambient air and salt water environments
    Engineering Fracture Mechanics, 2014
    Co-Authors: Heath Edward Misak, V. Sabelkin, V.y. Perel, Shankar Mall
    Abstract:

    Abstract Uniaxial and Biaxial Fatigue crack growth behavior of aluminum alloy, 2024-T3 was characterized under air and salt water environments using cruciform specimen with a horizontal pre-crack in L–T orientation. Crack propagated coplanar to the pre-crack under Biaxial Fatigue with Biaxiality ratios of 0.5 and 1 and non-coplanar to the pre-crack with Biaxiality ratio of 1.5. Fatigue crack growth versus crack driving force relationships showed two regions. The crack growth rates and damage mechanisms were different depending upon Biaxiality ratio in these two regions as well as in two test environments. These were also compared with counterparts from uniaxial Fatigue.

  • crack growth behavior of 7075 t6 under Biaxial tension tension Fatigue
    International Journal of Fatigue, 2013
    Co-Authors: Heath Edward Misak, V. Sabelkin, V.y. Perel, Shankar Mall
    Abstract:

    Abstract Crack growth behavior of aluminum alloy 7075-T6 was investigated under in-plane Biaxial tension–tension Fatigue with stress ratio of 0.5. Two Biaxiality ratios, λ (=1 and 1.5) were used. Cruciform specimens with a center hole, having a notch at 45° to the specimen’s arms, were tested in a Biaxial Fatigue test machine. Crack initiated and propagated coplanar with the notch for λ = 1 in L–T orientation, while it was non-coplanar for λ = 1.5 between L–T and T–L orientations. Uniaxial Fatigue crack growth tests in L–T and T–L orientations were also conducted. Crack growth rate in region II was practically the same for Biaxial Fatigue with λ = 1 in L–T orientation and for the uniaxial Fatigue in L–T or T–L orientations, while it was faster for Biaxial Fatigue with λ = 1.5 at a given crack driving force. However, Fatigue damage mechanisms were quite different in each case. In region I, crack driving force at a given crack growth rate was smallest for Biaxial Fatigue with λ = 1.5 and for uniaxial Fatigue in T–L orientation, followed by Biaxial Fatigue with λ = 1 and uniaxial Fatigue in L–T orientation in ascending order at a given crack growth rate.

  • corrosion Fatigue crack growth behavior of 7075 t6 under Biaxial tension tension cyclic loading condition
    Engineering Fracture Mechanics, 2013
    Co-Authors: Heath Edward Misak, V. Sabelkin, V.y. Perel, Shankar Mall
    Abstract:

    Abstract Biaxial and uniaxial Fatigue crack growth of aluminum alloy 7075-T6 was characterized under air and salt water (3.5%) environments. Biaxial Fatigue increased crack growth rate in region I relative to uniaxial Fatigue under both environments. Biaxial Fatigue increased crack growth rate in region II relative to uniaxial Fatigue under salt environment. Crack growth rates in region I were comparable in air and salt environments, while they were faster in salt water than air environment in region II. Biaxial Fatigue in salt environment exhibited intergranular cracks along with main transgranular fracture. A mechanism for Biaxial corrosion Fatigue crack growth is proposed.

Siddhant Datta - One of the best experts on this subject based on the ideXlab platform.

  • effects of overload mode mixity on Fatigue damage behavior and governing micromechanisms in aa7075 under Biaxial Fatigue loading
    International Journal of Fatigue, 2021
    Co-Authors: Abhay K. Singh, Aditi Chattopadhyay, Siddhant Datta, Nam Phan
    Abstract:

    Abstract An investigation into the effects of overload mode-mixity on crack growth behavior and governing micromechanisms of AA7075 T6 has been conducted. Cruciform AA7075 T6 specimens were subjected to constant amplitude planar Biaxial Fatigue with single overloads, and key Fatigue damage behavior, including Fatigue life, crack growth rate, and recovery distance, were investigated and correlated to overload parameters. Additionally, SEM fractography was conducted to identify and relate fracture surface features to governing Fatigue damage micromechanisms. An increase in Fatigue life was observed for all cases of mode-mixity, with the minimum increase occurring at 45°. The mix-mode overloads also caused crack retardation in all cases. In the shear dominant overloads, however, initial post-overload crack acceleration occurred and was immediately followed by crack retardation. Microscale analysis showed distinct fracture features in the pre-overload, transient, and post-overload regions for both tensile and shear dominant overloads.

  • Characterization of crack propagation behavior in Al-7075 under in-plane Biaxial Fatigue loading with shear overloads
    International Journal of Fatigue, 2020
    Co-Authors: Abhay K. Singh, Aditi Chattopadhyay, Siddhant Datta, Nam Phan
    Abstract:

    Abstract Effect of shear overloads in an otherwise constant amplitude, tensile Biaxial Fatigue loading is investigated using a cruciform specimen of Al 7075-T651, and the crack propagation behavior and governing micromechanisms are characterized. It was observed that with an increase in shear overload ratio Fatigue life of the specimen is increased and the crack growth rate is significantly affected. This behavior is attributed to the combined effects of competing mechanisms including compressive residual stress, plasticity induced crack closure, and strain hardening. The fractographic study revealed features of shear fracture in the transient region and tensile fracture in the pre-overload region and post-overload region.

  • Fatigue damage behavior in carbon fiber polymer composites under Biaxial loading
    Composites Part B-engineering, 2019
    Co-Authors: Travis Skinner, Aditi Chattopadhyay, Siddhant Datta, Asha Hall
    Abstract:

    Abstract An investigation into the damage accumulation and propagation behavior in carbon fiber reinforced polymer (CFRP) composites under complex in-phase Biaxial Fatigue loading has been conducted. The goal is to capture early stage damage and obtain an improved understanding of damage propagation and associated degradation in material properties. Both cross ply and quasi isotropic laminate configurations have been studied and the tests were conducted under constant amplitude in-phase Biaxial loading. An optimization technique was used to design the cruciform specimens for each stacking sequence. To understand the propagation of damage from the micro-to the macroscale, the fractured surfaces were analyzed, during various stages of Fatigue, using electron microscope assisted fractography and a high-resolution camera. Material property degradation was determined by measuring the change in specimen stiffness to analyze the progression of Fatigue damage and is correlated to the micro- and macroscale damage mechanisms and the Biaxial Fatigue loading parameters. The results provide insight into the initiation and propagation of damage mechanisms in CFRP composites which is essential to understanding the Fatigue behavior of composite materials under complex multiaxial loadings.

  • Fatigue crack propagation under Biaxial Fatigue loading with single overloads
    International Journal of Fatigue, 2018
    Co-Authors: Siddhant Datta, Aditi Chattopadhyay, Nagaraja Iyyer, Nam Phan
    Abstract:

    Abstract The crack propagation behavior and the governing crack growth micromechanisms in aluminum alloy under in-plane Biaxial Fatigue loading with single overloads, of different magnitudes and occurring at different Fatigue crack lengths, is investigated. The microscale fracture mechanisms governing crack growth behavior under these conditions are identified through detailed fractography. Crack growth retardation behavior observed due to the occurrence of single overloads is correlated with overload magnitude, instantaneous Fatigue crack length, crack-tip plasticity and fracture surface morphology. The results obtained provide insight into the relationship between macroscale crack growth behavior to microstructural mechanisms, which is essential to understanding the Fatigue behavior of metallic materials under variable amplitude Biaxial loading scenarios.

V.y. Perel - One of the best experts on this subject based on the ideXlab platform.

  • Crack growth behavior under Biaxial Fatigue with phase difference
    International Journal of Fatigue, 2015
    Co-Authors: Shankar Mall, V.y. Perel
    Abstract:

    Abstract Crack growth behavior of aluminum alloy 7075-T6 was characterized under in-plane Biaxial tension–tension Fatigue with phase differences of 90° or 180° between the two applied orthogonal cyclic loads. The initial single crack, created under the Biaxial Fatigue without any phase difference, splits into two symmetric cracks under the Biaxial Fatigue with the phase difference. The split cracks grow without any further branching. Directions of split cracks deviate sharply from the direction of the initial single crack. Under both phase differences of 90° and 180°, lengths of both split cracks are almost the same at a certain number of cycle. Strain energy release rate versus crack growth rate relationships of the split cracks are almost equal to each other. Further, sum of strain energy release rates at a given crack growth rate of both split cracks is equal to that of a single crack under the Biaxial Fatigue without phase difference. Analytical and finite element analyses are presented to explain the splitting of a crack due to the phase difference between the applied Biaxial cyclic loads.

  • Biaxial tension tension Fatigue crack growth behavior of 2024 t3 under ambient air and salt water environments
    Engineering Fracture Mechanics, 2014
    Co-Authors: Heath Edward Misak, V. Sabelkin, V.y. Perel, Shankar Mall
    Abstract:

    Abstract Uniaxial and Biaxial Fatigue crack growth behavior of aluminum alloy, 2024-T3 was characterized under air and salt water environments using cruciform specimen with a horizontal pre-crack in L–T orientation. Crack propagated coplanar to the pre-crack under Biaxial Fatigue with Biaxiality ratios of 0.5 and 1 and non-coplanar to the pre-crack with Biaxiality ratio of 1.5. Fatigue crack growth versus crack driving force relationships showed two regions. The crack growth rates and damage mechanisms were different depending upon Biaxiality ratio in these two regions as well as in two test environments. These were also compared with counterparts from uniaxial Fatigue.

  • crack growth behavior of 7075 t6 under Biaxial tension tension Fatigue
    International Journal of Fatigue, 2013
    Co-Authors: Heath Edward Misak, V. Sabelkin, V.y. Perel, Shankar Mall
    Abstract:

    Abstract Crack growth behavior of aluminum alloy 7075-T6 was investigated under in-plane Biaxial tension–tension Fatigue with stress ratio of 0.5. Two Biaxiality ratios, λ (=1 and 1.5) were used. Cruciform specimens with a center hole, having a notch at 45° to the specimen’s arms, were tested in a Biaxial Fatigue test machine. Crack initiated and propagated coplanar with the notch for λ = 1 in L–T orientation, while it was non-coplanar for λ = 1.5 between L–T and T–L orientations. Uniaxial Fatigue crack growth tests in L–T and T–L orientations were also conducted. Crack growth rate in region II was practically the same for Biaxial Fatigue with λ = 1 in L–T orientation and for the uniaxial Fatigue in L–T or T–L orientations, while it was faster for Biaxial Fatigue with λ = 1.5 at a given crack driving force. However, Fatigue damage mechanisms were quite different in each case. In region I, crack driving force at a given crack growth rate was smallest for Biaxial Fatigue with λ = 1.5 and for uniaxial Fatigue in T–L orientation, followed by Biaxial Fatigue with λ = 1 and uniaxial Fatigue in L–T orientation in ascending order at a given crack growth rate.

  • corrosion Fatigue crack growth behavior of 7075 t6 under Biaxial tension tension cyclic loading condition
    Engineering Fracture Mechanics, 2013
    Co-Authors: Heath Edward Misak, V. Sabelkin, V.y. Perel, Shankar Mall
    Abstract:

    Abstract Biaxial and uniaxial Fatigue crack growth of aluminum alloy 7075-T6 was characterized under air and salt water (3.5%) environments. Biaxial Fatigue increased crack growth rate in region I relative to uniaxial Fatigue under both environments. Biaxial Fatigue increased crack growth rate in region II relative to uniaxial Fatigue under salt environment. Crack growth rates in region I were comparable in air and salt environments, while they were faster in salt water than air environment in region II. Biaxial Fatigue in salt environment exhibited intergranular cracks along with main transgranular fracture. A mechanism for Biaxial corrosion Fatigue crack growth is proposed.