Physical Acoustics and the Properties of Solids

Enhanced ultrasonically assisted turning of a β-titanium alloy

“…An acoustic softening effect, where an apparent static shear stress necessary for plastic deformation is significantly reduced under intense ultrasonic excitation, was observed in several metals including titanium since its discovery in Zn crystals [13]. It is believed that acoustic energy is absorbed by dislocations and grain-boundaries, enhancing plastic deformation [14], since little attenuation was observed in defect-free regions.…”

Evaluating the integrity of adhesive bonds by the measurement of acoustic properties under stresses

“…The phase change at the interface is influenced by the load level. In the plot between the applied force and the phase change encountered at the interface, the slope of the curve is given by Ft, where Ft = (dt/dp) where, t = time-of-travel and p = stress (1) In good quality bonds, the adhesive interface encounters a state of residual stress. When a small load is applied under steady state condition, there is a change in the phase of the reflected sound wave at the bond interface.…”

“…Dependence of acoustic velocity on the elastic constants and density is well known [1]. The elasticity and the density are influenced by temperature as well as by stress.…”

Polar Columnar and Tetrahedratic Phases

“…where the contribution ∼ E ij is the usual dielectric term with six (4) independent coefficients for triclinic C 1 (monoclinic C 2 ) symmetry [16]. The next term is characteristic of all ferroelectric materials.…”