2026-01-26 東京農工大学
図1 液滴衝突時の基板内応力場計測：柔らかい基板に衝突する液滴（各パネル上部）と、偏光カメラで捉えた光弾性計測データ（各パネル左下）、およびそれを解析して再構成した応力場（各パネル右下）の時間変化（単位ms（ミリ秒）、1000分の1秒）を示している。液滴の衝突から約0.1 ms後に、基板内に応力が広がっていき、液滴が平たくなる1.0 msには応力がほぼ消えていることが、光弾性法計測データ（応力を黄緑色で表示）とその解析結果（応力を赤色で表示）から読み取れる。（Yokoyama et al., Nature Communications, 2025を基に作成）
＜関連情報＞
- https://www.tuat.ac.jp/outline/disclosure/pressrelease/2025/20260126_01.html
- https://www.tuat.ac.jp/documents/tuat/outline/disclosure/pressrelease/2025/20260126_01.pdf
- https://www.nature.com/articles/s41467-025-67790-6
弾性基材への液滴衝突力におけるスケーリング・クロスオーバー Scaling crossover in droplet impact force on elastic substrates
Yuto Yokoyama,Hirokazu Maruoka,Kaie Matsunuma & Yoshiyuki Tagawa
Nature Communications Published:28 January 2026
DOI:https://doi.org/10.1038/s41467-025-67790-6
Abstract
Droplet impacts are fundamental to fluid-structure interactions, shaping processes from erosion to bioprinting. While previous scaling laws have provided insights into droplet dynamics, force scaling laws remain insufficiently understood, particularly for soft substrates where both the droplet and substrate deform significantly. Here, we show that droplet impacts on elastic substrates exhibit a scaling crossover in maximum impact force, transitioning from inertial force scaling, typical for rigid substrates under high inertia, to Hertzian impact scaling, characteristic of rigid spheres on elastic substrates. Using high-speed photoelastic tomography, we captured high-resolution dynamic stress fields and identified a similarity parameter governing the interplay between droplet inertia, substrate elasticity, and deformation time scales. Our findings redefine how substrate properties influence impact forces, demonstrating that droplets under high inertia-long thought to follow inertial force scaling-can instead follow Hertzian impact scaling on soft substrates. This framework provides practical insights for designing soft, impact-resistant materials.
