Dynamic viscoelastic polymer data is traditionally time-temperature shifted to obtain a temperature shift function (TSF) and then fitted to various analytical models. The process of obtaining the TSF can introduce considerable procedural or operator bias. Nevertheless the Havriliak and Negami (HN) model using the TSF methodology can generally describe polymers that are rheologically simple. In this paper the “wicket” plot is utilized as an important tool in analyzing data, as it is completely independent of time-temperature shifting (TTS). Using the wicket plot the data is fit to the HN equation to determine the four material HN constants independent of TTS. Having obtained the complete spectra of dynamic properties the specific relaxation time (frequency) at each temperature is obtained by matching the HN curve to the experimental data at that temperature thus determining the TSF. The procedure is illustrated by analyzing computer-generated data with random error in modulus and loss and finally real data on a standard material.

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Experimental results are presented for sound scattering from elastic prolate and oblate spheroidal scattering objects. The backscattered waveform, the target strength versus incident angle, and the frequency response of the echoes are obtained directly from experimental data or via numerical processing of these data. Analytical models and computer codes are developed for estimating the arrival times of the elastic echoes and the resonance modes.

The predictions of resonance frequencies for elongated elastic cylinders and spheroids, based on various methods of approach, were discussed in a number of papers in recent years. In the present study, the regions of applicability of the phase matching method for surface waves and of the longitudinal bar wave approximation are examined by comparing the predicted results with the results of T-matrix calculations or with the results of scattering experiments.