Droplet impact on highly deformable substrate and three-dimensional stress fields measurement by photoelastic tomography
ORAL
Abstract
Understanding the droplet impact behavior on soft substrates is important in many industrial technologies, such as 3D inkjet bioprinters. When the droplet impacts on the deformable substrate, energy loss due to substrate deformation, which depends on the impact stress, must be considered. Therefore, measurement of the three-dimensional (3D) stress field within the soft substrate is essential to understand the droplet impact. To do so, we use photoelasticity. When circularly polarized light enters a material under a stressed state, it exits as elliptically polarized light with photoelastic parameters, which depend on the stress state. Photoelastic tomography can be used to reconstruct the 3D stress field from the measured photoelastic parameters. We developed a novel photoelastic tomography algorithm, combining vector tomography and conventional photoelastic tomography. Linear interpolation and matrix calculations are used to improve the conventional method. We applied this tomography algorithm for the droplet impact onto a soft substrate which is an unsteady phenomenon. We simultaneously measured droplet impact on a highly deformable substrate (gelatin gel) and the stress field in the substrate using a high-speed polarization camera.
*This work was supported by JSPS KAKENHI Grant Numbers JP20H00222, JP20H00223, and JP22J13343, JST PRESTO Grant Number JPMJPR21O5, Japan, and the U.S. National Science Foundation through award CMMI-1462993. Y.Y. acknowledges the financial support of FLOuRISH JIRITSU Fellowship program from Tokyo University of Agriculture and Technology.
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Publication:1. Benjamin Mitchell, Yuto Yokoyama, Ali Nassiri, Yoshiyuki Tagawa, Yannis Korkolis, Brad Kinsey, An investigation of Hertzian contact in soft materials using photoelastic tomography, arXiv:2207.03900, (2022). 2. Yuto Yokoyama, Benjamin R. Mitchell, Ali Nassiri, Brad L. Kinsey, Yannis P. Korkolis, Yoshiyuki Tagawa, Integrated Photoelasticity in a Soft Material: Phase Retardation, Azimuthal Angle, and Stress-Optic Coefficient, submitted to Optics and Lasers in Engineering, available at SSRN: https://ssrn.com/abstract=4171604 (2022).
