Visualization of adhesion phenomenon connecting nano and macro of rubber friction

2022 Fiscal Year Final Research Report

• Project/Area Number: 21K18670
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Review Section: Medium-sized Section 18:Mechanics of materials, production engineering, design engineering, and related fields
• Research Institution: Niigata University
• Principal Investigator: Nitta Isami 新潟大学, 自然科学系, 教授 (30159082)
• Co-Investigator(Kenkyū-buntansha): 月山 陽介 新潟大学, 自然科学系, 准教授 (00533639)
• Project Period (FY): 2021-07-09 – 2023-03-31
• Keywords: ゴム摩擦 / 真実接触面積 / メニスカス / 凝着 / 広視野レーザ顕微鏡

Outline of Final Research Achievements

The influence of meniscus forces acting on rubber and glass was investigated from a macroscopic point of view. In smooth rubber specimens, the real contact area, Ar, greatly increased slightly with contact time in dry condition. Due to the intervention of water, Ar increased significantly with contact time. This is due to the meniscus force attracting the rubber to the glass and expelling the water. In the case of ethanol, which evaporates quickly, Ar increased in a short time. The rate of increase of the friction coefficient did not correspond to that of Ar. The reason for this is that the Ar increased by meniscus force is subject to compressive stress, but when the water evaporates, the meniscus force disappears and the compressive stress changes to tensile stress. Therefore, when frictional force is applied, the Ar that was under compressive stress disappears.

Free Research Field

機械工学

Academic Significance and Societal Importance of the Research Achievements

ゴムは摩擦係数が高いので種々の物体搬送に使われる．原子間力顕微鏡AFMを使ったナノ・マイクロ領域でのゴム摩擦の要因は解明されているが，靴底などマクロ領域ではゴムの摩擦力は正確には予測できない．その大きな理由は，マクロ領域においてメニスカス力が適切に評価できないことである．研究代表者が開発した広視野レーザ顕微鏡ではマクロ領域のゴム表面全体の真実接触面積Arを精度良く測定できる．マクロ領域においてメニスカス力がArに及ぼす影響が解明できれば，なぜ水が介在するとゴムが滑りやすくなるのか．また，その状態でゴムを擦り続けると摩擦力が高くなるのかを解明でき，ゴムをより良く利用すことができるようになる．