LAMAR UNIVERSITY

Triboloby teaches that the lateral force required to slide two surfcaes against each other (friction force) is in fact proportional to the contact area. Tha 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 norman and alteral 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 maipulations 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 norman and lateral retention forces) leading to the transformative research. Another feature that this will add to the CAB is the possiblitiy 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.

Clarification of Codes