An approximate JKR theory for elliptical contacts

JKR theory describes how surface energy modifies the Hertz theory of contact between elastic solids, giving rise to a larger contact area for positive loads, and to a finite tensile load 1.5 pi R Delta gamma in order to separate the solids. Here the original theory for circular contacts is extended to the general elliptical Hertzian contact. To a good approximation, the contact area remains elliptical, but the eccentricity varies continuously with the load, and at pull-off is substantially less than the Hertzian value.