1985 Volume 47 Issue 1 Pages 19-27
The computer controlled equipment for measuring the dynamic properties of the farm products was designed, the plastic erasers considered as the standard viscoelastic materials were excited by the random force and the frequency response functions were estimated in real time. These viscoelastic materials were described mathematically by the mechanical systems consisting of the rheological models and the mass. The general method by which the twenty-four dynami models produced through combination of these elements could be reduced to five basic models to describe the measured frequency response curves was discussed, and the system parametesrs were estimated with the non-linear least spuare method between the measured frequency response curves and the theoretical ones.
It was found that the most suitable mechanical model was composed of the mass and Voigt model on the strength of the uniqueness, stability and convergency of the estimated parameters and reproducibility of the measured response curves. This proposed model was applied to the excited cubic samples of the apple and it was verified that the frequency response curves of the apple samples could be described by this mechanical model. The relations between the estimated parameters and the quality of the apple were investigated and it was confirmed that the quality changes of the apple during storage could be detected through these parameters in real time.
