Generalized interpolation material point approach to high melting explosive with cavities under shock

Abstract

Abstract. Criterion for contacting is critically important for the Generalized Interpolation Material Point(GIMP) method. We present an improved criterion by adding a switching function. With the method dynamical response of high melting explosive(HMX) with cavities under shock is investigated. The physical model used in the present work is an elastic-to-plastic and thermal-dynamical model with Mie-Grüneissen equation of state. We mainly concern the influence of various parameters, including the impacting velocity v, cavity size R, etc, to the dynamical and thermodynamical behaviors of the material. For the colliding of two bodies with a cavity in each, a secondary impacting is observed. Correspondingly, the separation distance D of the two bodies has a maximum value D max in between the initial and second impacts. When the initial impacting velocity v is not large enough, the cavity collapses in a nearly symmetric fashion, the maximum separation distance D max increases with v. When the initial shock wave is strong enough to collapse the cavity asymmetrically along the shock direction, the variation of D max with v does not show monotonic behavior. Our numerical results show clear indication that the existence of cavities in explosive helps the creation of "hot spots".

Temperature pattern dynamics in shocked porous materials

“…The contact algorithm is the core of a MPM. What we used here is an improved one given in recent literature [5]. The MPM combined with the contact algorithm in ref.…”

“…The MPM combined with the contact algorithm in ref. [5] is also referred to Grain Contact Material Point Method (GCMPM).…”

“…The inhomogeneity of the material may change significantly its shock response behaviors. When being reacted by a weak shock, the embedded cavity in the material may result in a secondary impact; When being reacted by a strong shock, jet phenomena may occur at the cavity [4,5]. Globally speaking, shock wave reaction results in various characteristic regimes, for example, "high pressure regimes", "high temperature regimes", "regimes with high particle speeds", "regimes with high deviatoric stresses", etc.…”

Simulation Study of Shock Reaction on Porous Material

“…The computational mesh may be the original one or a newly defined one, choose for convenience, for the next time step. More details of the algorithm is referred to [22,23]. …”

“…The material-point method was originally introduced in fluid dynamics by Harlow, et al [19] and extended to solid mechanics by Burgess, et al [20], then developed by various researchers, including us [21,22,23]. At each time step, calculations consist of two parts: a Lagrangian part and a convective one.…”