MRI-R2: Developing Instrumentation for measuring decoupled normal and lateral retention forces for systems of drops on surfaces

这个奖项是根据2009年美国复苏和再投资法案(公法111-5)资助的。摩擦学告诉我们，滑动两个表面所需的侧向力(摩擦力)实际上与接触面积成正比。因此，Amonton定律是一个特例，其中粗糙表面的接触面积恰好随载荷线性增加。PI最近提出了一个系统，在该系统中，尽管接触面积增加，但侧向力随着法向力的减小而减小。这种情况发生在表面上的液滴上，这一发现是通过使用一种仪器实现的，该仪器首次允许法向和横向保持力之间的有限解耦，即离心式附着力天平(CAB)。在这项建议中，PI将开发CAB，使其首次能够完全独立地操纵法向和横向固位力，这对于研究横向固位力与法向力的相关性至关重要。启用测量将改变我们考虑正交固位力相互影响的方式。这将在表面科学中创造一种新的范式(旨在发现法向保持力和横向保持力之间的关系)，从而导致变革性研究。这将为驾驶室增加的另一个特点是在零侧向力下降低法向力的可能性。在这种情况下，液滴只能垂直于表面移动，并最终以负法向力飞离表面。这样的实验将是对杜普雷方程的第一次实验直接测试--这是表面科学中的一个中心问题--从而有可能从根本上改变我们对杨-杜普雷方程的理解，从而再次导致一项变革性的研究。该仪器将被用来研究表面上的液滴，以及任何其他两种垂直保留力可能相互影响的情况。

0960229Tadmor"This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5)."Tribology teaches that the lateral force required to slide two surfaces against each other (friction force) is in fact proportional to the contact area. The Amonton law, therefore, is a special case in which the contact area of a rough surface happens to increase linearly with the load. The PI recently presented a system in which the lateral force decreases with the normal force in spite of the fact that the contact area increases. This happens for drops on surfaces, and the discovery was enabled using an instrument that allowed for the first time some limited decoupling between normal and lateral retention forces, namely the Centrifugal Adhesion Balance (CAB). In this proposal the PI will develop the CAB such that it will enable for the first time complete independent manipulations of the normal and lateral retention forces, which is essential for the study of the dependence of lateral retention forces on the normal forces. Enabling the measurement will change the way we consider the mutual influence of orthogonal retention forces. This will create a new paradigm in surface science (aiming to find relation between normal and lateral retention forces) leading to transformative research. Another feature that this will add to the CAB is the possibility to decrease the normal force under zero lateral force. In this configuration the drop can only move normal to the surface, and will eventually fly off the surface at some negative normal force. Such an experiment will be the first experimental direct test for the Dupre equation - a central issue in surface science - thereby bearing the potential to radically change our understanding of the Young-Dupre equation thereby leading again to a transformative research. This instrument will be used to study drops on surfaces and also any other case in which two orthogonal retention forces may influence each other.