Duan Z. Zhang

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A numerical scheme of computing quantities involving gradients of shape functions is introduced for the material point method (MPM), so that the quantities are continuous as material points move across cell boundaries. The noise and instability caused by cell crossing of the material points are then eliminated. In this scheme, the formulas used to compute(More)
  • Duan Z Zhang
  • Physical review. E, Statistical, nonlinear, and…
  • 2005
Particle contacts in a granular material are formed at different times and have different contact ages, the differences between current time and the times when the contacts were formed. The probability distribution of the contact ages is one of the important statistical properties of particle interactions. The rate of the probability relaxation is proved to(More)
We have recently developed a general-purpose non linear system solver environment for complex physics computations on unstructured grids. This environment, named CartaBlanca, was described at last year's Java Grande Forum. CartaBlanca employs a finite-volume method, [1]. The solution of the non linear algebraic systems, arising from representing the(More)
The particle-in-cell method (PIC), especially the latest version of it, the material point method (MPM), has shown significant advantage over the pure Lagrangian method or the pure Eulerian method in numerical simulations of problems involving large deformations. It avoids the mesh distortion and tangling issues associated with Lagrangian methods and the(More)
For two-species particulate systems, ensemble averaged continuity and momentum equations for each species are derived based on the Liouville equation of the system. The ensemble average used is species specific. It is found that the interaction between species results in not only the interspecies force but also a stress in the momentum equations. In the(More)
A polymeric solid is modeled as a network of beads and strings. Beads in the polymer are divided into bead groups represented by the segment end points. Based on the equation of motion for each bead in the system, a macroscopic equation of motion for the polymer is derived. Velocity fluctuations of beads result in a pressure, the isotropic component of the(More)
We find that a severely rolled FeCo alloy has anomalous enhancement of the rotated-cube {100}<011> texture component and a decrease of the {111} components after annealing, which is contrast to the recrystallization behaviors reported in traditional BCC metals and alloys. The local texture measurements show that two kinds of grains with obviously different(More)