PSI - Issue 13

Koji Uenishi et al. / Procedia Structural Integrity 13 (2018) 670–675 Uenishi et al. / Structural Integrity Procedia 00 (2018) 000–000

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4. Conclusions The two specific fracture patterns, “top”-type and “orange segments”-type, have been identified in a series of dynamic laboratory experiments of free-falling ice spheres impinging upon a flat plate. In order to understand the fracture mechanics behind the generation of these fracture patterns and incorporate influence of fracture in the simulations of the cooling process of a granular system, for example, more quantitative data about the relation between the impact energy of the sphere and the distributions of sizes and masses of the fragmented segments and pieces of ice as well as more rigorous evaluation of the fracture development and wave-fracture interaction, etc., is required. Currently, more exact and quantitative contact time during each impact is being measured using laser displacement sensors and pressure sensors (Uenishi et al., 2018). The new experimental observations suggest that the rise time (the time needed to reach a certain pressure owing to impact) is basically shorter when the induced fracture is the “orange segments”-type. This shorter rise time renders a longer effective contact time and hence waves of longer lengths, which is consistent with our earlier speculations. Since ice is one of the most familiar brittle solid materials in our environments, the obtained results may assist in comprehending the generation mechanisms of a wide range of physical phenomena, not only the formation of a ring system but also fracture of icebergs and avalanches. Acknowledgements The financial support by the Japan Society for the Promotion of Science (JSPS) through the “KAKENHI: Grant in-Aid for Scientific Research (C)” Program (No. 16K06487) and the “Invitation Fellowship Program for Research in Japan” is kindly acknowledged. References Benjemaa, M., Glinsky-Olivier, N., Cruz-Atienza, V. M., Virieux, J., 2009. 3-D Dynamic Rupture Simulations by a Finite Volume Method. Geophysical Journal International 178, 541–560. Bridges, F.G., Hatzes, A., Lin, D.N.C., 1984. Structure, Stability and Evolution of Saturn’s Rings. Nature 309, 333–335. Delcourte, S., Fezoui, L., Glinsky-Olivier, N., 2009. A High-Order Discontinuous Galerkin Method for the Seismic Wave Propagation. ESAIM: Proc. 27, 70–89. Dilley J., Crawford D., 1996. Mass Dependence of Energy Loss in Collisions of Icy Spheres: An Experimental Study. Journal of Geophysical Research 101(E4), 9267–9270. Etienne, V., Chaljub, E., Virieux, J., Glinsky, N., 2010. An hp-Adaptive Discontinuous Galerkin Finite-Element Method for 3-D Elastic Wave Modelling. Geophysical Journal International 183, 941–962. Martins, J. A. C., Oden, J. T., 1983. A Numerical Analysis of a Class of Problems in Elastodynamics with Friction. Computer Methods in Applied Mechanics and Engineering 40, 327–360. Middleton, G. V., Wilcock P. R., 1994. Mechanics in Earth and Environmental Sciences. Cambridge University Press, Cambridge, 475 pages. Oden, J. T., Martins, J. A. C., 1985. Models and Computational Methods for Dynamic Friction Phenomena. Computer Methods in Applied Mechanics and Engineering 52, 527–634. Uenishi, K., Yano, R., Yoshida, T., Yamagami, K., Suzuki, K., 2013. Inelastic collisions between icy bodies: Dependence on impact velocity and its fluctuations, Japan Geoscience Union Meeting. Chiba, Japan, PPS21-P20. Uenishi, K., Yamachi, H., Yamagami, K., Sakamoto, R., 2014. Dynamic Fragmentation of Concrete Using Electric Discharge Impulses. Construction and Building Materials 67(B), 170–179. Uenishi, K., Shigeno, N., Sakaguchi, S., Yamachi, H., Nakamori, J., 2016a. Controlled Disintegration of Reinforced Concrete Blocks Based on Wave and Fracture Dynamics. Procedia Structural Integrity 2, 350–357. Uenishi, K., Shigeno, N., Sakaguchi, S., Yano, R., Suzuki, K., 2016b. Dynamic Impact-Induced Fracture Development in Ice Spheres, in “Contributions to the Foundations of Multidisciplinary Research in Mechanics” . In: Floryan, J. M. (Ed.). IUTAM 2016 International Program Committee, Montreal, pp. 2170–2171. Uenishi, K., Yoshida, T., Sakaguchi, S., Suzuki, K., 2017. Dynamic fracture patterns formed in transparent ice spheres by impact loading, Materials and Mechanics Conference. Sapporo, Japan, GS1007, pp. 1828–1829. Uenishi, K., Hasegawa, T., Yoshida, T. Sakaguchi, S., Suzuki, K., 2018. Dynamic Fracture and Fragmentation of Ice Materials, in “ICTAEM 2018, Structural Integrity, 5” . In: Gdoutos, E. E. (Ed.). Springer International Publishing AG, Cham, pp. 242–243.