Bulk wave attenuation in epoxies has been found experimentally to be a linear function of frequency. Anecdotal evidence suggests that the formulations used for bulk wave attenuation to be input to computational propagation models, including models for guided waves, can take many forms: Either the simple linear relationship between attenuation and frequency can be input directly, or any of a number of analytic models could, in principle, be used – examples being the Maxwell, Kelvin-Voigt and Zener anelastic solid models, or the hysteretic damping model sometimes employed for studies of structural vibrations. This paper considers the physical bases of these various models, as well as multiple degree of freedom models that have their origins in dielectric theory. It is shown that a simple two degree of freedom adaptation of the Zener model provides a good simulation of experimentally observed data for both attenuation and phase speed over a wide frequency band.

Ultrasonic compression wave propagation in a curing thermoset is considered in the context of phenomenological models of viscoelasticity used as a basis to simulate observed wave attenuation and phase velocity. The anelastic solid model gives a qualitative match to experimental results which is improved through the use of the Cole-Davidson (CD) extended model. The CD model when fitted to experimental data gave a parameter which could be used to track molecular polydispersity in the curing material.

A novel ferromagnetic resonance technique has been developed, allowing both swept-field and swept-frequency absorption spectra to be produced using a single broadband spectrometer. A straightforward through-transmission method removes the need for a commercial network analyzer, making this a versatile yet inexpensive tool for the characterization of magnetic materials. Initial results from gamma ferric oxide tape show good agreement with published data from a conventional, swept-field fixed-frequency FMR spectrometer and indicate the potential of this technique which also enables measurements of the magnetic anisotropy. Swept-frequency and swept-field data are presented for a range of sample orientations.

The origin of anomalous refractive index values in ion implanted optical waveguides in some crystalline materials has been an outstanding problem for several years. By use of complementary X-ray edge-topography and Raman microprobe imaging we have found evidence that changes in the dislocation density after implantation correlate with changes in the dynamic response of the lattice to light. This implies that the effects of reduced dislocation density may be related to the origin of the refractive index anomalies, possibly as a result of strain relief. Further support for this hypothesis comes from the fact that the original bulk dislocation density is recovered throughout the crystal by annealing to the temperature at which the refractive index anomalies are lost.