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Center for Mathematical Science and Advanced Technology (MAT)

Seminar Schedule

[MAT Seminar]

Date:
2025/02/05(Wednesday) 13:00-15:00
Language:
English
Location:
MAT Theater, 508, InformationTechnology Building 5F, Yokohama Institute for Earth Sciences (YES)
Speaker:
Keisuke Taga (Department of Physics, Waseda University)
Title:
The pattern formation model of the tape-peeling trace by deformed adhesives
Abstract:
It is known that when adhesive tape is peeled, the structure of the peeling front changes depending on the peeling speed, resulting in various patterns on the peeling trace. At slow peeling speeds, a tunnel structure forms as air penetrates the adhesive fluid of the tape, giving it a white appearance. At fast peeling speeds, this tunnel structure collapses, resulting in a black appearance. Particularly at intermediate peeling speeds, these two structures switch chaotically, forming a fractal pattern of spatiotemporal chaos—an intriguing phenomenon in statistical physics and nonlinear systems. Previous studies have proposed models to explain this pattern formation. However, in this study, we proposed other mechanism and formulate a model based on it. In this talk, we will first introduce our proposed model and discuss how fractal patterns emerge within it. We will then compare our model with previous models to highlight its distinctive features and similarities. Finally, we will explore the proposed model from the perspective of scaling properties. Our results suggest that the tape- peeling trace belongs to the directed percolation universality class.

[MAT Seminar]

Date:
2025/1/15(Wednesday) 13:00-15:00
Language:
English
Location:
MAT Theater, 508, InformationTechnology Building 5F, Yokohama Institute for Earth Sciences (YES)
Speaker:
Sota Arakawa (MAT)
Title:
Numerical Investigation on the Compressive Behavior of Hierarchical Granular Piles
Abstract:
Hierarchical granular piles composed of aggregates are key structural features in both geoscience and planetary science, from fault gouge in seismic zones to the internal structures of comets. Although experimental studies have suggested a multi-step evolution in their packing structure, this hypothesis has lacked numerical validation. In this study, we performed large-scale numerical simulations using the discrete element method to investigate the compressive behavior of hierarchical granular piles. We successfully reproduced and confirmed a three-stage evolution process: (i) rearrangement of the aggregate packing structure, (ii) plastic deformation of small aggregates, and (iii) elastic deformation of constituent particles. Additionally, we developed a semi-analytical model for the compression curve, offering insights into the compressive stages and structural dynamics.