Failure criterion of glass fabric reinforced plastic laminates

Failure criteria are derived for several modes of failure (in unaxial tensile or compressive loading, or biaxial combined tensile-compressive loading) in the case of closely woven plain fabric, coarsely-woven plain fabric, or roving glass cloth reinforcements. The shear strength in the interaction formula is replaced by an equation dealing with tensile or compressive strength in the direction making a 45 degree angle with one of the anisotropic axes, for the uniaxial failure criteria. The interaction formula is useful as the failure criterion in combined tension-compression biaxial failure for the case of closely woven plain fabric laminates, but poor agreement is obtained in the case of coarsely woven fabric laminates

Convective particle transport arising from poloidal inhomogeneity in tokamak H mode

In tokamak high-confinement modes (H modes), a large poloidal flow exists within an edge transport barrier, and the electrostatic potential and density profiles can be steep both in the radial and poloidal directions. The two-dimensional structures of the electrostatic potential, density, and flow velocity near the edge of a tokamak plasma are investigated. The analysis is carried out with the momentum conservation law using the shock ordering. For the case with a strong radial electric field (H-mode case), a particle flux is induced from asymmetry of the poloidal electric field in the transport barrier. This convective transport is found to depend weakly on collisionality, and changes its direction in accordance with the direction of the radial electric field, the toroidal magnetic field, and the plasma current. The divergence of a particle flux is a source of temporal variation of the density, and there are negative divergence regions both in the inward and outward flux cases. Thus this convective particle flux is a new candidate for the cause of the rapid establishment of the density pedestal after the onset of low to high confinement mode (L/H) transition

Two-dimensionally Steep Structure of the Electric Field in Tokamak H-mode

The rapid formation of a density pedestal on an L/H transition has been raising a question why the rapid density evolution is induced. Formation of a poloidal shock structure is predicted in H-mode transport barriers, and consideration of the two-dimensional structure both in the radial and poloidal directions is inevitable to clarify the formation mechanism of the H-mode pedestal. The analyses are carried out with edge plasmas in tokamak H modes, which are induced either spontaneously or by electrode biasing. Two-dimensional structures of the potential, density and flow velocity are calculated with the momentum conservation equation. The validity of the one-dimensional L/H transition theory and the iterative process to obtain the two-dimensional structure are confirmed by our analysis. A steep electric field structure both in the radial and poloidal directions is obtained. The two-dimensional electric field induces radial ion fluxes, which increase in the H-mode transport barrier and affect the electric field. If the Boltzmann relation is violated, radial electron fluxes are induced, and affect the density evolution. Reduction of anomalous transport by the steep gradient of the radial electric field, and generation of the particle fluxes associated with the two-dimensional structure influence the rapid formation of the steep gradients in H-mode plasmas. A transport model including both effects is constructed to reveal the self-consistent mechanism of the density pedestal formation in the L/H transition