The Experts below are selected from a list of 315 Experts worldwide ranked by ideXlab platform
P. Grassl - One of the best experts on this subject based on the ideXlab platform.
-
Corrosion Induced Cracking Modelled by a Coupled Transport-Structural Approach
Cement and Concrete Research, 2017Co-Authors: C. Fahy, Domenico Gallipoli, S.j. Wheeler, P. GrasslAbstract:Transport of corrosion products into pores and cracks in concrete must be considered when predicting corrosion Induced Cracking in reinforced concrete structures, since this transport significantly delays the onset of Cracking and spalling by reducing the amount of radial displacement imposed on the concrete at the steel/concrete interface. We aim to model this process by means of a coupled transport-structural approach, whereby the transport of corrosion products is determined by a pressure gradient generated by the confined volumetric expansion due to the transformation of steel into corrosion products. This pressure driven transport was studied by using both an axisymmetric thick-walled cylinder model and a network approach. The network approach was then applied to corrosion Induced Cracking experiments reported in the literature.
-
Transport-Structural Modelling of Corrosion Induced Cracking
2016Co-Authors: C. Fahy, Domenico Gallipoli, S.j. Wheeler, P. GrasslAbstract:Transport of corrosion products into pores and cracks in concrete must be considered when predicting corrosion Induced Cracking in reinforced concrete structures, since this transport significantly delays the onset of Cracking and spalling by reducing the amount radial displacement displacement imposed on the concrete at the steel/concrete interface. We aim to model this process by means of a transport-structural approach, whereby the transport part is driven by a pressure gradient generated by the volumetric expansion due to the transformation of steel into corrosion products. This pressure driven transport was introduced in an analytical axisymmetric thickwalled cylinder model and a numerical network approach. The influence of Cracking and permeability on corrosion Induced Cracking process with increasing inner displacement is investigated with these two approaches.
-
Transport-Structural Modelling of Corrosion Induced Cracking
Proceedings of the 9th International Conference on Fracture Mechanics of Concrete and Concrete Structures, 2016Co-Authors: C. Fahy, Domenico Gallipoli, S.j. Wheeler, P. GrasslAbstract:International audienceTransport of corrosion products into pores and cracks in concrete must be considered when predicting corrosion Induced Cracking in reinforced concrete structures, since this transport significantly delays the onset of Cracking and spalling by reducing the amount radial displacement displacement imposed on the concrete at the steel/concrete interface. We aim to model this process by means of a transport-structural approach, whereby the transport part is driven by a pressure gradient generated by the volumetric expansion due to the transformation of steel into corrosion products. This pressure driven transport was introduced in an analytical axisymmetric thickwalled cylinder model and a numerical network approach. The influence of Cracking and permeability on corrosion Induced Cracking process with increasing inner displacement is investigated with these two approaches
-
lattice modelling of corrosion Induced Cracking and bond in reinforced concrete
Cement & Concrete Composites, 2011Co-Authors: P. Grassl, T G DaviesAbstract:Abstract A lattice approach is used to describe the mechanical interaction of a corroding reinforcement bar, the surrounding concrete and the interface between steel reinforcement and concrete. The cross-section of the ribbed reinforcement bar is taken to be circular, assuming that the interaction of the ribs and the surrounding concrete can be captured by a cap-plasticity interface model. The expansive corrosion process is represented by an Eigenstrain in the lattice elements forming the interface between concrete and reinforcement. Several pull-out tests with varying degree of corrosion are analysed. The numerical results are compared with experiments reported in the literature. The influence of the properties of concrete are studied. The proposed lattice approach offers insight into corrosion Induced Cracking and its influence on bond strength.
-
lattice modelling of corrosion Induced Cracking and bond in reinforced concrete
arXiv: Materials Science, 2011Co-Authors: P. Grassl, T G DaviesAbstract:A lattice approach is used to describe the mechanical interaction of a corroding reinforcement bar, the surrounding concrete and the interface between steel reinforcement and concrete. The cross-section of the ribbed reinforcement bar is taken to be circular, assuming that the interaction of the ribs of the deformed reinforcement bar and the surrounding concrete can be captured by a cap-plasticity interface model. The expansive corrosion process is represented by an Eigenstrain in the lattice elements forming the interface between concrete and reinforcement. Several pull-out tests with varying degree of corrosion are analysed. The numerical results are compared with experiments reported in the literature. The influence of the properties of concrete are studied. The proposed lattice approach offers insight into corrosion Induced Cracking and its influence on bond strength.
Wuyang Chu - One of the best experts on this subject based on the ideXlab platform.
-
Hydrogen-Induced Cracking and hydrogen embrittlement of Ni2MnGa FSMAs
Journal of Physics D: Applied Physics, 2010Co-Authors: Liancheng Shen, Wuyang Chu, Lijie QiaoAbstract:Hydrogen-Induced Cracking and hydrogen embrittlement of Ni50Mn30Ga20 ferromagnetic shape memory alloys (FSMAs) were studied through indentation and tension experiments supplemented with in situ observation. The results showed that for Ni50Mn30Ga20 FSMAs, hydrogen-Induced Cracking could occur with the residual stress caused by indentation during dynamic hydrogen charging. Hydrogen-Induced Cracking was initiated and propagated during dynamic hydrogen charging in the pre-cracked specimens under constant deflection. The fracture toughness KIC decreased from 1.9 MPa m1/2 for the uncharged specimens to 0.4 MPa m1/2 for the samples charged with hydrogen. The possible mechanism of hydrogen-Induced Cracking and hydrogen embrittlement for Ni50Mn30Ga20 FSMAs is due to diffusible hydrogen decreasing the efficient surface energy.
-
Hydrogen blistering and hydrogen-Induced Cracking in amorphous nickel phosphorus coating
Journal of Non-crystalline Solids, 2007Co-Authors: Qian Zhou, L.j. Qiao, Wuyang ChuAbstract:Abstract Hydrogen blistering and hydrogen-Induced Cracking in amorphous Ni–P coating were studied. The results showed that hydrogen blistering and hydrogen-Induced Cracking in Ni–P coating could form during cathodic charging. Hydrogen blister could nucleate through hydrogen atoms diffusing into free volume cavity besides preexisted void. With increasing hydrogen pressure, shear bands appeared on the surface of hydrogen blister, and then hydrogen-Induced Cracking initiated and propagated along the wall of hydrogen blister.
-
Hydrogen-Induced Cracking and its anisotropy of a PZT ferroelectric ceramics
Science in China Series E, 2003Co-Authors: Yi Wang, Lijie Qiao, Wuyang Chu, Kewei GaoAbstract:Threshold stress intensity factor of hydrogen-Induced Cracking (HIC), K IH , of a lead zirconate titanate ferroelectric ceramics (PZT-5) has been measured during dynamic charging with various current densities at constant load using notched tensile specimens with poling direction parallel or perpendicular to the crack plane. The results show that K IH reveals anisotropy, and the threshold stress intensity factor for the specimen with poling direction parallel to the crack plane, K IH a , is greater than that perpendicular to the crack plane, K IH b similar to the anisotropy of fracture toughness, K IC . The normalized threshold stress intensity factor of HIC, however, does not reveal anisotropy, and decreass linearly with logarithm of hydrogen concentration, C 0 , i.e. K IH a / K IC a = K IH b / K IC b =0.4—0.15 ln C 0 . Therefore, the anisotropy of HIC is the same as that of the fracture toughness, and is due to the anisotropy of the stress-Induced 90° domain switching.
-
Hydrogen-Induced Cracking by nanovoids in 310 stainless steel
Science in China Series E: Technological Sciences, 1998Co-Authors: Yizhong Huang, Qizhi Chen, Yanbin Wang, Wuyang ChuAbstract:Hydrogen-Induced Cracking was investigated by TEMin-situ tension in hydrogenated stainless steel of type 310. It was found experimentally that hydrogen-Induced Cracking happens via nanovoid nucleation followed by quasi-cleavage along {111} planes whenC H is higher. Otherwise, in the case of lowerC H, hydrogen enhances ductile fracture via hydrogen-enhanced microvoid nucleation, growth and connection. A new model was proposed based on the present experiments. Dislocations break away from defect atmospheres and move away from the DFZ, leaving vacancy and hydrogen clusters along {111} planes. Hydrogen tends to combine with vacancy clusters and initiate nanovoids along {111} planes. Dense nanovoids connect each other, resulting in brittle Cracking. Scattered nanovoids grow into microvoids or even macrovoids, leading to ductile fracture.
-
Threshold stress intensity for hydrogen-Induced Cracking of tubular steel
Scripta Materialia, 1997Co-Authors: Bai-lin Jiang, Lijie Qiao, Yanbin Wang, Wuyang ChuAbstract:The susceptibility of tubular steels to hydrogen-Induced Cracking (HIC) depends on metallurgical as well as environmental factors. Hydrogen atoms, produced as a result of corrosion of the inside wall, diffuse through the pipewall and are trapped at heterogeneous sites in the steel. When the hydrogen reaches a critical concentration at some site, which depends on the composition and microstructure of steel, blistering and/or hydrogen-Induced Cracking (HIC) will occur. The critical concentration of diffusible hydrogen for blistering in the tubular steel was C{sub th} = 8.38 ppm. Hydrogen-Induced fracture under constant load could occur even though the concentration of diffusible hydrogen, C{sub 0}, was less than the C{sub th}. The threshold stress intensity for HIC in the tubular steel decreased with the increase in diffusible hydrogen concentrations, C{sub 0}, i.e., K{sub IH}(MPam{sup 1/2}) = 46 {minus} 12.5lnC{sub 0}(ppm).
Y F Cheng - One of the best experts on this subject based on the ideXlab platform.
-
characterization of inclusions of x80 pipeline steel and its correlation with hydrogen Induced Cracking
Corrosion Science, 2011Co-Authors: H B Xue, Y F ChengAbstract:Abstract In this work, the microstructures of an X80 pipeline steel were characterized, and their susceptibilities to hydrogen-Induced Cracking (HIC) were investigated by hydrogen-charging, electrochemical hydrogen permeation and surface characterization. It is found that the microstructure of X80 pipeline steel consists of a polygonal ferrite and bainitic ferrite matrix, with martensite/austenite (M/A) constituents distributing along grain boundaries. The inclusions existing in the steel include those enriched with Si, Al oxide, Si–ferric carbide and Al–Mg–Ca–O mixture, respectively. The majority of inclusions are Si-enriched. Upon hydrogen-charging, cracks could be initiated in the steel in the absence of external stress. The cracks are primarily associated with the Si- and Al oxide-enriched inclusions. The diffusivity of hydrogen in X80 steel at room temperature is 2.0 × 10−11 m2/s, and the estimated hydrogen trapping density in the steel is as high as 3.33 × 1027 m−3.
-
effects of hydrogen charging on the susceptibility of x100 pipeline steel to hydrogen Induced Cracking
International Journal of Hydrogen Energy, 2009Co-Authors: Chen Dong, Zhiyong Liu, Y F ChengAbstract:Abstract In this work, the hydrogen-Induced Cracking (HIC) behavior of X100 pipeline steel was investigated by a combination of tensile test, electrochemical hydrogen permeation measurement and surface characterization techniques. The effect of inclusions in the steel on the crack initiation was analyzed. Results demonstrated that the amount of hydrogen-charging into the X100 steel specimen increases with the charging time and charging current density. Hydrogen-charging will enhance the susceptibility of the steel to HIC. The cracks initiate primarily at inclusions, such as aluminum oxides, titanium oxides and ferric carbides, in the steel. The diffusivity of hydrogen at room temperature in X100 steel is determined to be 1.04 × 10 −8 cm 2 /s.
Frank Y Cheng - One of the best experts on this subject based on the ideXlab platform.
-
hydrogen trapping and hydrogen Induced Cracking of welded x100 pipeline steel in h2s environments
International Journal of Hydrogen Energy, 2017Co-Authors: Lijun Gan, Jing Liu, Feng Huang, Xiaoyu Zhao, Frank Y ChengAbstract:Abstract Hydrogen Induced Cracking (HIC) susceptibility of the welded X100 pipeline steel was evaluated in NACE “A” solution at room temperature according to the NACE TM0284-2011 standard. Both the kinetic parameters of the permeability ( J ∞ L ) , the apparent diffusivity (Dapp) and the concentration of reversible and irreversible hydrogen in the base metal and welded joint of X100 pipeline steel were quantitatively investigated by hydrogen permeation test. The results showed that the welded joint with an inhomogeneous microstructure had a higher trap density and more susceptible to HIC due to two orders of magnitude larger in the concentration of irreversible hydrogen than that of base metal, though all presenting poor HIC resistance for both base metal and the welded joint. The HIC cracks initiated from the inclusions enriching in Al, Ca, Si, Mn. The cracks are primarily transgranular, accompanying with limited intergranular ones.
Lijie Qiao - One of the best experts on this subject based on the ideXlab platform.
-
Brittle film-Induced Cracking of ductile substrates
Acta Materialia, 2015Co-Authors: Tao Guo, Lijie Qiao, Xiaolu Pang, Alex A. VolinskyAbstract:Abstract Film and substrate mechanical integrity is essential for the whole system’s performance. In the present study, Cracking of brass ductile substrate Induced by brittle TiN film fracture was observed. Counter-intuitively, instead of protecting the ductile substrate, a brittle film can cause its premature fracture, as demonstrated here experimentally. Brittle film fracture could induce Cracking of ductile substrate at considerably low strain level. Analytical calculation based on energy conservation during crack propagation is presented to explain this phenomenon of film-Induced Cracking. It is shown that crack depth penetrated into the substrate is a function of both crack velocity and the number of dislocations emitted from the crack tip. Relatively thick brittle films and fast propagating cracks favor fracture of the ductile substrates. The critical crack velocity, which can induce the Cracking of brass substrate, is 61 m/s. The presence of brittle film could not only prevent dislocations escaping from the surface of the crystal and inhibit dislocations emitting from surface dislocation sources, but also initiate a channel crack with high velocity due to brittle fracture. Both of them contribute to crack propagation in soft brass substrate. This study provides an alternative view to the notion that a brittle film can protect the ductile substrate from damage.
-
Hydrogen-Induced Cracking and hydrogen embrittlement of Ni2MnGa FSMAs
Journal of Physics D: Applied Physics, 2010Co-Authors: Liancheng Shen, Wuyang Chu, Lijie QiaoAbstract:Hydrogen-Induced Cracking and hydrogen embrittlement of Ni50Mn30Ga20 ferromagnetic shape memory alloys (FSMAs) were studied through indentation and tension experiments supplemented with in situ observation. The results showed that for Ni50Mn30Ga20 FSMAs, hydrogen-Induced Cracking could occur with the residual stress caused by indentation during dynamic hydrogen charging. Hydrogen-Induced Cracking was initiated and propagated during dynamic hydrogen charging in the pre-cracked specimens under constant deflection. The fracture toughness KIC decreased from 1.9 MPa m1/2 for the uncharged specimens to 0.4 MPa m1/2 for the samples charged with hydrogen. The possible mechanism of hydrogen-Induced Cracking and hydrogen embrittlement for Ni50Mn30Ga20 FSMAs is due to diffusible hydrogen decreasing the efficient surface energy.
-
Hydrogen-Induced Cracking and its anisotropy of a PZT ferroelectric ceramics
Science in China Series E, 2003Co-Authors: Yi Wang, Lijie Qiao, Wuyang Chu, Kewei GaoAbstract:Threshold stress intensity factor of hydrogen-Induced Cracking (HIC), K IH , of a lead zirconate titanate ferroelectric ceramics (PZT-5) has been measured during dynamic charging with various current densities at constant load using notched tensile specimens with poling direction parallel or perpendicular to the crack plane. The results show that K IH reveals anisotropy, and the threshold stress intensity factor for the specimen with poling direction parallel to the crack plane, K IH a , is greater than that perpendicular to the crack plane, K IH b similar to the anisotropy of fracture toughness, K IC . The normalized threshold stress intensity factor of HIC, however, does not reveal anisotropy, and decreass linearly with logarithm of hydrogen concentration, C 0 , i.e. K IH a / K IC a = K IH b / K IC b =0.4—0.15 ln C 0 . Therefore, the anisotropy of HIC is the same as that of the fracture toughness, and is due to the anisotropy of the stress-Induced 90° domain switching.
-
Threshold stress intensity for hydrogen-Induced Cracking of tubular steel
Scripta Materialia, 1997Co-Authors: Bai-lin Jiang, Lijie Qiao, Yanbin Wang, Wuyang ChuAbstract:The susceptibility of tubular steels to hydrogen-Induced Cracking (HIC) depends on metallurgical as well as environmental factors. Hydrogen atoms, produced as a result of corrosion of the inside wall, diffuse through the pipewall and are trapped at heterogeneous sites in the steel. When the hydrogen reaches a critical concentration at some site, which depends on the composition and microstructure of steel, blistering and/or hydrogen-Induced Cracking (HIC) will occur. The critical concentration of diffusible hydrogen for blistering in the tubular steel was C{sub th} = 8.38 ppm. Hydrogen-Induced fracture under constant load could occur even though the concentration of diffusible hydrogen, C{sub 0}, was less than the C{sub th}. The threshold stress intensity for HIC in the tubular steel decreased with the increase in diffusible hydrogen concentrations, C{sub 0}, i.e., K{sub IH}(MPam{sup 1/2}) = 46 {minus} 12.5lnC{sub 0}(ppm).
-
Hydrogen Accumulation and Hydrogen-Induced Cracking of API C90 Tubular Steel
CORROSION, 1997Co-Authors: Y. H. Cheng, Lijie Qiao, Yanbin Wang, L. Chen, Wuyang ChuAbstract:Abstract A study was undertaken of hydrogen accumulation on grain boundaries, at inclusions, and near a kneaded notch tip; the susceptibility for blistering; and hydrogen-Induced Cracking (HIC) of ...
