**Body Waves Abstract**

### **Radiation of Body Waves Induced by the Sliding of an Elastic Half-Space Against a Rigid Surface**

G.G. Adams

Abstract

The steady sliding of a flat half-space against a rigid surface with a
constant interfacial coefficient of friction is investigated. It is
shown here that steady sliding is compatible with the formation of a
pair of body waves (a plane dilatational wave and a plane shear wave)
radiated from the sliding interface. Each wave propagates at a
different angle such that the trace velocities along the interface are
equal and supersonic with respect to the elastic medium. The angles
of wave propagation are determined by the Poisson's ratio and by the
coefficient of friction. The amplitude of the waves are indeterminant,
subject only to the restriction that the perturbations in interface
contact pressure and tangential velocity satisfy the inequality
constraints for unilateral sliding contact.

It is also found that a rectangular wave train, or a rectangular pulse,
can allow for motion of the two bodies with a ratio of remote shear to
normal stress which is less than the coefficient of friction. Thus the
*apparent* coefficient of friction is less than the *interface*
coefficient of friction. Furthermore it is shown that the apparent
friction coefficient decreases with increasing speed even if the
interface friction coefficient is speed-independent. This result
supports the interpretation of certain friction behavior as being a
consequence of the dynamics of the system, rather than strictly
as an interface property. No distinction is made between static and
kinetic friction.

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### Journal Publications