[SY-O9] Symposium O-9

[SY-O9] Meso-scale SPH simulation for friction and wear between elastic-plastic solids with various asperities

^○Natsuko Nakagawa Sugimura^1,2, Le Van Sang², Yuji Mihara¹, Hitoshi Washizu² (1.Dept. of Mechanical Engineering, Tokyo City Univ., Japan, 2.Grad. Sch. of Simulation Studies, Univ. of Hyogo,, Japan)

We made the meso(micron-oder) scale model to simulate friction, wear and adsorption with heating between elastic-plasic bodies. Constitutive equation is based on the continuum equation and calculated with SPH(Smoothed Particle Hydrodynamics). SPH is one of particle methods to solve continuum equation with mesh free. SPH was initially developed for the hydrodynamics by Lucy et al., but it was applied to calculation of solids afterwards by Swegle et al. and has gained good results. In SPH, the physical variables of the particles are reconstructed by the adding the physical variables of the surrounding particles by an appropriate weighting called kernel. SPH particles are not truly particles like molecules but only physical fields. However, we regard the particles on the friction surfaces as also coarse grained molecules and add the interaction forces directly between such “particles”, which is mimicking the particle approach. That is, our model is what continuum calculation and particle calculation are mixed. It is just meso-scale that is situated in between the macro scale to demand continuum approach and the nano scale to demand particle approach. Although its physical discontinuity is not yet resolved, if the using both approaches confirm the reproducing valid frictional phenomena, the mechanism of its discontinuity may also be resolved. At this time, for the purpose to efficiently realize the calculation of the great amount of particles with parallel code, we use the FDPS open platform by Iwasawa & Makino et al. to create our simulation code.

We set the tens of micron system in which elastic-plastic bodies with various asperities are faced and one body is sliding under the vertical load to cause shear friction. So far, in the system with interface with regular asperities, the elasticity, plasticity, friction cure, heat generation and conduction were to some extent qualitatively expressed, although the frictional results depend on the several parameters and SPH boundary processing. Then, we will firstly show the characteristics of our model with regular asperity system in detail. Moreover, we will discuss the frictional properties changing the shape of asperities, i.e. with realistic asperities.