Stiffness evaluation of contacting surfaces by bulk and interface waves

Area of Science:

• Materials Science
• Solid Mechanics
• Acoustics

Background:

• Understanding interfacial stiffness is crucial for predicting contact mechanics.
• Previous studies have explored normal and tangential stiffness but often lack frequency-dependent analysis.

Purpose of the Study:

• To experimentally determine the normal and tangential stiffnesses of a contacting interface between polished aluminum blocks.
• To investigate the influence of contact pressure and frequency on these interfacial stiffnesses.

Main Methods:

• Ultrasonic spectroscopy was employed to measure bulk wave reflection coefficients (longitudinal and transverse).
• The anti-symmetric mode interface wave velocity was measured.
• Measurements were conducted on polished aluminum blocks under varying contact pressures (up to 3.8 MPa).

Main Results:

• Interfacial stiffnesses were quantified as functions of both frequency and applied contact pressure.
• The ratio of tangential to normal stiffness was analyzed against existing theoretical and experimental data.
• Frequency dependence of stiffness was observed and attributed to interfacial inhomogeneity and energy loss.

Conclusions:

• The study provides experimental data on frequency- and pressure-dependent interfacial stiffnesses.
• The findings contribute to a deeper understanding of contact mechanics at interfaces.
• The observed frequency dependence highlights the complex nature of interfacial behavior.