Using an ultrasonic device consisting of a pulser-receiver, an oscilloscope, and several ultrasonic transducers, we transmitted longitudinal and transversal ultrasonic waves with frequencies of 0.5 and 1.0 MHz through spruce specimen. In particular, we are interested in a continuum (micro-) mechanical explanation of the relationship between stiffness tensor components and the ultrasonic frequency, by reviewing the theoretical foundations of (micro- )dynamics and acoustics. The direction-dependent normal and shear stiffness components (i.e. the diagonal terms of the elastic stiffness tensor) of the anisotropic natural composite 'spruce' were determined and compared with data obtained from static and ultrasonic tests given in the literature.
展开▼
