Wang Zhenqing

The interaction of plane SH-waves and non-circular cavity surfaced with lining in anisotropic media

In this paper, we use the complex function method for solving the problem of interaction of plane SH-waves and circular cavity surfaced with lining in anisotropic media. Anisotropic media can be used to simulate the conditions of the geology. This problem can be handled by using the method similar to that incorporated in Ref. [5] to define the scattering waves in media, added with the given boundary condition of the circular cavity.In this paper, as illustrated in the examples, the results and discussions of numerical studies have been done for the interaction of plane SH-waves and two kinds of circular cavities, surfaced with lining made up of different materials, in anisotropic media.

Perfect elastic-viscoplastic field at mode I dynamic propagating crack-tip

The viscosity of material is considered at propagating crack-tip. Under the assumption that the artificial viscosity coefficient is in inverse proportion to power law of the plastic strain rate, an elastic-viscoplastic asymptotic analysis is carried out for moving crack-tip fields in power-hardening materials under plane-strain condition. A continuous solution is obtained containing no discontinuities. The variations of numerical solution are discussed for mode I crack according to each parameter. It is shown that stress and strain both possess exponential singularity. The elasticity, plasticity and viscosity of material at crack-tip only can be matched reasonably under linear-hardening condition. And the tip field contains no elastic unloading zone for mode I crack. It approaches the limiting case, crack-tip is under ultra-viscose situation and energy accumulates, crack-tip begins to propagate under different compression situations.

Numerical simulation for aerodynamic heating and opposing jet thermal protection

Based on the theory and semi-empirical formulas, the surface heating flux of warhead at zero attack angle under aerodynamic heating is calculated by using reference enthalpy method, and the equilibrium curves of temperature for radiation of wall are obtained, by which the anti-thermal effects of blunt leading edge is proved in this paper. At the same time, the anti-thermal effects of thermal protection system with opposing jet are simulated by using methods of CFD. The heating flux of wall under opposing jet is predicted, and the numerical simulation results are well agreement with the experiment results.

Mechanical investigations on high temperature oxidation of ZrB 2 -SiC UHTCs

A model taking into accounts of mass conservation equation, kinetics of oxidation reaction, phase transformation has been proposed to describe the high temperature behavior of the oxidation layer of ZrB2-SiC composites along with Arrhenius law and Eshelbypsilas equivalent inclusion theorem. Volume fraction change of constituents and the elastic modulus of the depletion layer have been theoretically and numerically. The results show good agreement with the experimental phenomena.

Asymptotic analysis of mode I propagating crack-tip field in a creeping material

Adopting an elastic-viscoplastic, the asymptotic problem of mode I propagating crack-tip field is investigated. Various asymptotic solutions resulting from the analysis of crack growing programs are presented. The analysis results show that the quasistatically growing crack solutions are the special case of the dynamic propagating solutions. Therefore these two asymptotic solutions can be unified.

Stress-strain field near the crack-tip of an incompress rubber-like material

This paper contains an asymptotic finite-deformation analysis about the elastostatic field near the crack-tip in an incompress rubber-like material. The cracktip field is divided into two narrowing sectors and one expanding sector. By the new strain energy function and deformation pattern, we derive and solve the asymptotic equations fo reach sector of the tip field. The singularity of the crack-tip field is discussed. The curves of stress-strain of the crack-tip field for an incompress rubberlike material are given and the dominant behaviors of stress and strain near the crack-tip are revealed.