Bw. Drinkwater et al., A STUDY OF THE INTERACTION BETWEEN ULTRASOUND AND A PARTIALLY CONTACTING SOLID-SOLID INTERFACE, Proceedings - Royal Society. Mathematical, physical and engineering sciences, 452(1955), 1996, pp. 2613-2628
Citations number
28
Journal title
Proceedings - Royal Society. Mathematical, physical and engineering sciences
The measurement of the reflection of ultrasonic waves from a partially
contacting solid-solid interface can be used to study the contact con
ditions at that interface. This paper describes measurements and predi
ctions of the reflection of ultrasonic waves from partially contacting
aluminium-aluminium interfaces, performed in the low frequency regime
where the wavelength of the ultrasound is large compared to the size
of the gaps. The proportion of the incident wave which is reflected at
the interface (the reflection coefficient) was measured as a function
of frequency with a single wideband ultrasonic transducer. When load
was applied across the interface three regions of contact can be seen;
no contact, partial contact and perfect contact. In the no contact re
gion the measured reflection coefficient was unity at all frequencies.
In the partial contact region the measured reflection coefficient inc
reased with frequency. No measurements were taken in the perfect conta
ct region in which the reflection coefficient is known to be zero at a
ll frequencies as this state is the same as a continuous piece of alum
inium. The reflection coefficient variation with frequency was modelle
d using a spring model, good agreement between experiments and predict
ions being achieved. Reflection coefficient measurements were then use
d to study the contact between two aluminium surfaces under repeated l
oading and unloading cycles. Plastic flow on first loading was evident
while subsequent loading cycles revealed largely elastic behaviour. B
oth elastic and plastic statistical contact models, as well as a numer
ical contact model, were used to predict the variation of interfacial
stiffness with pressure. These models agreed qualitatively with the ex
perimentally determined stiffness variations and the predicted stiffne
ss was within an order of magnitude of the measured value in all cases
.