The Experts below are selected from a list of 7023 Experts worldwide ranked by ideXlab platform

M.m. Hall - One of the best experts on this subject based on the ideXlab platform.

  • critique of the ford andresen Film Rupture model for aqueous stress corrosion cracking
    Corrosion Science, 2009
    Co-Authors: M.m. Hall
    Abstract:

    Abstract The Ford–Andresen Film Rupture model for aqueous stress corrosion cracking has obtained a prominent position in the nuclear reactor industry. The model is said to have superior predictive capabilities because it is derived from a fundamental understanding of the Film Rupture-repassivation mechanism of crack advance. However, a critical review shows that there are conceptual and mathematical problems with the Ford–Andresen model development; there are inconsistencies among the stated and implied assumptions, the crack tip current density expression lacks the necessary dependence on crack tip strain rate and the fundamental proportionality that exists between crack tip strain rate and crack growth rate is overlooked and omitted from the model development. Consequently, the Ford–Andresen model must be considered neither phenomenologically nor fundamentally supported.

  • Film Rupture model for aqueous stress corrosion cracking under constant and variable stress intensity factor
    Corrosion Science, 2009
    Co-Authors: M.m. Hall
    Abstract:

    Abstract A Film Rupture model for aqueous stress corrosion cracking is developed and used to predict kinetics of crack growth under constant and variable stress intensity factor. The model predicts that creep is necessary for sustained crack growth and creep rate limits crack velocity for constant K and dK / da loading. Contrary to recent thinking, the crack tip strain due to crack advance is viewed as a result, not a cause of crack growth. The crack tip strain gradient elevates and maintains crack tip stress as the crack propagates, which enables creep and sustained crack growth. The model provides a basis for understanding effects of positive and negative K – variation on crack growth.

  • Critique of the Ford–Andresen Film Rupture model for aqueous stress corrosion cracking
    Corrosion Science, 2009
    Co-Authors: M.m. Hall
    Abstract:

    Abstract The Ford–Andresen Film Rupture model for aqueous stress corrosion cracking has obtained a prominent position in the nuclear reactor industry. The model is said to have superior predictive capabilities because it is derived from a fundamental understanding of the Film Rupture-repassivation mechanism of crack advance. However, a critical review shows that there are conceptual and mathematical problems with the Ford–Andresen model development; there are inconsistencies among the stated and implied assumptions, the crack tip current density expression lacks the necessary dependence on crack tip strain rate and the fundamental proportionality that exists between crack tip strain rate and crack growth rate is overlooked and omitted from the model development. Consequently, the Ford–Andresen model must be considered neither phenomenologically nor fundamentally supported.

D.x. Liu - One of the best experts on this subject based on the ideXlab platform.

Xiaozhen Yang - One of the best experts on this subject based on the ideXlab platform.

  • molecular dynamics simulations of Film Rupture in water surfactant systems
    Journal of Physical Chemistry B, 2009
    Co-Authors: Wenhong Yang, Bin Kong, Xiongfei Zhang, Xiaozhen Yang
    Abstract:

    Molecular dynamics simulation has been performed on water/surfactant Film Rupture in order to investigate foam stability. A periodic boundary Film model which was simulated in a lateral dimension o...

  • Molecular dynamics simulations of Film Rupture in water/surfactant systems.
    The journal of physical chemistry. B, 2009
    Co-Authors: Wenhong Yang, Bin Kong, Xiongfei Zhang, Xiaozhen Yang
    Abstract:

    Molecular dynamics simulation has been performed on water/surfactant Film Rupture in order to investigate foam stability. A periodic boundary Film model which was simulated in a lateral dimension of 8 × 8 nm2 for 4 ns was established to stand for a part of a foam bubble. On the basis of critical Film thickness, which is the lowest thickness before Film Rupture, a stability index was calculated to describe the capabilities of surfactants to stabilize water Films. We investigated the influence of Film size and simulation duration on the critical thickness and proved that our model is reasonable. The stability index versus surfactant concentration curve suggests that the capabilities of three surfactants—linear alkylbenzene sulfonate (LAS), sodium dodecyl sulfate (SDS), and heptaethylene glycol monododecyl ether (C12E7)—in stabilization of water Film decrease in the order of SDS > LAS > C12E7. In the present study, the simulated results have been validated by the foam generation and decay experiment results,...

Omar Matar - One of the best experts on this subject based on the ideXlab platform.

  • Surfactant driven flows overlying a hydrophobic epithelium: Film Rupture in the presence of slip.
    Journal of colloid and interface science, 2003
    Co-Authors: Yong Liang Zhang, Richard V. Craster, Omar Matar
    Abstract:

    Both for tear Films and along the airways within the lung, one has an extremely thin fluid layer overlying a biological substrate; in both cases surfactants either of natural origin, or artificially introduced, are important in driving fluid flows. There is evidence that slip can occur when hydrophilic liquids, similar to mucus or aqueous tear Films, overlie hydrophobic epithelium. Utilizing results from recent experimental findings we examine the possible influence of slip upon tear Film Rupture, important in so-called dry eye, and upon surfactant-induced flows within the lung, used in surfactant replacement therapy.

  • Analysis of tear Film Rupture: effect of non-Newtonian rheology.
    Journal of colloid and interface science, 2003
    Co-Authors: Yong Liang Zhang, Omar Matar, Richard V. Craster
    Abstract:

    We investigate the Rupture mechanism of a precorneal thin mucus coating sandwiched between the aqueous tear Film and the corneal epithelial surface with a monolayer of surfactant overlying the aqueous layer. The Ostwald constitutive relation is employed to model mucus and a linear equation of state describing the relationship between surface tension and surfactant concentration is adopted. Three nonlinear coupled evolution equations governing the transport of surfactant, mucus, and total liquid layer thicknesses, based on lubrication theory and a perturbation expansion technique, have been derived. The resulting equations are solved numerically in order to explore the influence of the rheological properties of mucus, aqueous-mucus thickness ratio, aqueous-mucus interfacial tension, Marangoni number, and surfactant concentration on both the onset of instability and tear Film evolution in the presence of van der Waals interactions, which could Rupture the tear Film. Our results reveal that the influence of rheological properties, aqueous-mucus thickness ratio, and interfacial tension on the time required for Film Rupture can be significant and varies considerably, depending on the magnitude of the Hamaker constants governing the strength of the van der Waals forces.

Richard V. Craster - One of the best experts on this subject based on the ideXlab platform.

  • Surfactant driven flows overlying a hydrophobic epithelium: Film Rupture in the presence of slip.
    Journal of colloid and interface science, 2003
    Co-Authors: Yong Liang Zhang, Richard V. Craster, Omar Matar
    Abstract:

    Both for tear Films and along the airways within the lung, one has an extremely thin fluid layer overlying a biological substrate; in both cases surfactants either of natural origin, or artificially introduced, are important in driving fluid flows. There is evidence that slip can occur when hydrophilic liquids, similar to mucus or aqueous tear Films, overlie hydrophobic epithelium. Utilizing results from recent experimental findings we examine the possible influence of slip upon tear Film Rupture, important in so-called dry eye, and upon surfactant-induced flows within the lung, used in surfactant replacement therapy.

  • Analysis of tear Film Rupture: effect of non-Newtonian rheology.
    Journal of colloid and interface science, 2003
    Co-Authors: Yong Liang Zhang, Omar Matar, Richard V. Craster
    Abstract:

    We investigate the Rupture mechanism of a precorneal thin mucus coating sandwiched between the aqueous tear Film and the corneal epithelial surface with a monolayer of surfactant overlying the aqueous layer. The Ostwald constitutive relation is employed to model mucus and a linear equation of state describing the relationship between surface tension and surfactant concentration is adopted. Three nonlinear coupled evolution equations governing the transport of surfactant, mucus, and total liquid layer thicknesses, based on lubrication theory and a perturbation expansion technique, have been derived. The resulting equations are solved numerically in order to explore the influence of the rheological properties of mucus, aqueous-mucus thickness ratio, aqueous-mucus interfacial tension, Marangoni number, and surfactant concentration on both the onset of instability and tear Film evolution in the presence of van der Waals interactions, which could Rupture the tear Film. Our results reveal that the influence of rheological properties, aqueous-mucus thickness ratio, and interfacial tension on the time required for Film Rupture can be significant and varies considerably, depending on the magnitude of the Hamaker constants governing the strength of the van der Waals forces.