Elastoplastic particles

Most solids are subjected to permanent deformation or breakup once the applied stresses exceed a certain limit. Hence, most solid particles may be classified into two categories elastoplastic particles and elastic-brittle particles. Typical elastoplastic materials include metals and polymers, while typical elastic-brittle materials include coal, activated carbon, and ceramics. Materials that are elastoplastic at room temperature may become brittle at low temperatures and those that are brittle at room temperature may become plastic at high temperatures. 

The material properties of solids are affected by a number of complex factors. In a gas-solid flow, the particles are subjected to adsorption, electrification, various types of deformation (elastic, plastic, elastoplastic, or fracture), thermal conduction and radiation, and stresses induced by gas-solid interactions and solid-solid collisions. In addition, the particles may also be subjected to various field forces such as magnetic, electrostatic, and gravitational forces, as well as short-range forces such as van der Waals forces, which may affect the motion of particles. 

The conducted tests leaded to developing grounds for the technology for dynamic vulcanization of materials with thermo-elastoplastic properties, in which a thermoplastic polymer constitutes a continuous phase, whereas the dispersed phase consists of cross-linked elastomer particles. Basic elastomers are polyisoprene with isotactivity level of 85% or higher and copolymer EOE containing over 30% of n-octene. 

Two of the most common classes of particle-dynamic simulations are termed hard-particle and soft-particle methods. Hard-particle methods calculate particle trajectories in response to instantaneous, binary collisions between particles, and allow particles to follow ballistic trajectories between collisions. This class of simulation permits only instantaneous contacts and is consequently often used in rapid flow situations such as are found in chutes, fluidized beds, and energetically agitated systems. Soft-particle methods, on the other hand, allow each particle to deform elastoplastically and compute responses using standard models from elasticity and tribology theory. This approach permits enduring particle contacts and is therefore the method of choice for mmbler apphcations. The simulations described in this chapter use soft-particle methods and have been validated and found to agree in detail with experiments. 

M. Galli, J. Botsis, J. Janczak-Rusch, An elastoplastic three-dimensional homogenization model for particle reinforced composites. Comput. Mater. Sci. 41, 312-321 (2008)... 

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