No abstract

SUMMARYConstructing a method for representing natural objects and natural phenomena is one of the important topics of research in the field of computer graphics. In the current research, the authors propose a method of realistically representing cracks that occur in 3D objects in computer graphics. Cracking is a familiar natural phenomenon that is seen on mud walls, the surface of rice fields, ceramics, and the bark of trees. The objective of the current research is to reproduce the cracking that occurs when an object that consists of mud or clay shrinks when it dries out. To represent cracking in computer graphics, rules based on observation or approaches based on simple physical models have been considered. However, the current research uses a method based on a physical model since changes in the material properties, environment, or external forces can easily be represented. Specifically, by introducing a spring network model to represent the shrinking, elasticity, and pliability of the clay and a moisture content model to represent the moisture movement within the object due to drying and integrating these two models, the authors simulate a mechanism for generating cracks due to drying. They also investigate a method of measuring the physical parameters that are used based on the moisture content. Finally, they performed experiments for 3D objects having various shapes to verify the effectiveness of the proposed method.

Abstract-The elastohydrodynamic lubrication model considering solid particles was set up. Taking effect of solid particles into account, the Reynolds equation was deduced. The elastohydrodynamic lubrication analysis of spur gear running-in was completed considering time-variant effect. Results show that oil film pressure in region 2 where particle is located increases dramatically but oil film thickness in region 2 decreases thinking about effects of solid particles. When particle size becomes greater oil film pressure increases obviously, oil film thickness diminishes. The minimum film thickness and maximum film pressure both diminish considering effects of solid particles.