The mixed-type integral equations for transient elastodynamic plane crack problems

In the present paper, by use of the boundary integral equation method and the techniques of Green fundamental solution and singularity analysis, the dynamic infinite plane crack problem is investigated. For the first time, the problem is reduced to solving a system of mixed-typed integral equations in Laplace transform domain. The equations consist of ordinary boundary integral equations along the outer boundary and Cauchy singular integral equations along the crack line. The equations obtained are strictly proved to be equivalent with the dual integral equations obtained by Sih in the special case of dynamic Griffith crack problem. The mixed-type integral equations can be solved by combining the numerical method of singular integral equation with the ordinary boundary element method. Further use the numerical method for Laplace transform, several typical examples are calculated and their dynamic stress intensity factors are obtained. The results show that the method proposed is successful and can be used to solve more complicated problems.

A new type of boundary integral-equation for plane problems of elasticity including rotational forces

Based on the idea proposed by Hu [Scientia Sinica Series A XXX, 385-390 (1987)], a new type of boundary integral equation for plane problems of elasticity including rotational forces is derived and its boundary element formulation is presented. Numerical results for a rotating hollow disk are given to demonstrate the accuracy of the new type of boundary integral equation.

The structure and the dynamics of poly(vinyl methyl ether) PVME and in PVME concentrated water solution : a study by neutron scattering and fully atomistic molecular dynamics simulations

175 p. : il.

Vortex dislocation in wake-type flow caused by local spanwise nonuniformity

DNS of spatiotemporal evolution of a wake-type flow is performed. In the incoming flow, a local spanwise nonuniformity in momentum defect is initially imposed. Results show that the spanwise nonuniformity leads to a series of symmetric twist vortex dislocation in downstream of the flow. Vortex line variations and substantial transition of vorticity from spanwise to the streamwise and vertical directions clearly feature the generation of a vortex dislocation and the real vortex linking in the dislocation. Dynamical process and the mechanism responsible for the vortex dislocation are described.