Use this URL to cite or link to this record in EThOS: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.518737
Title: Study in Dynamic Characterisation of Particulate Materials Using Low Magnitude Vibration
Author: Yanagida, Takeshi
Awarding Body: University of Teesside
Current Institution: Teesside University
Date of Award: 2002
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Abstract:
This thesis has been devoted to a study in dynamic characterisation of particulate materials using low magnitude vibration. Four types of experimental methodologies were investigated, which measure i) acceleration transmissibility, ii) dissipation energy, iii) effective mass and iv) apparent mass. Experiments were performed with low accelerations ranged from O.02-0.1g, in which the bed remains a coherent entity. Properties of both single and binary component systems were studied. Theoretical and numerical models were used to interpret the experimental results. The major implications in this thesis are summarised below. The use of acceleration transmissibility through a shallow bed enabled the dynamic properties: the elastic modulus and loss factor, to be quantified using analogue model techniques. The loss factor was found to be insensitive to the experimental variables within the range of this study. A model based upon contact mechanics gave a qualitative explanation for the insensitivity of the loss factor at small amplitudes. The properties of well-mixed binary systems were investigated and the mixing fraction dependence was analysed in terms of the two-phase series model. The energy dissipated within particulate materials was determined in terms of the hysteresis curve of the base force and displacement data. The measured dissipation energy data exhibited a significant energy peak as a function of frequency. In addition, results showed the existence of an optimised bed mass to give the maximum energy dissipation for the required frequency. The energy dissipation model developed gave not only a quantitative agreement with experimental data at the primary peak frequency range, but also a rigorous interpretation for the existence of the optimised bed mass in terms of equilibrium" of resonant and mass effects. The model was also found to be applicable to well-mixed binary systems. These experimental trends of the energy dissipation properties were qualitatively reproduced by numerical analysis using a 3D discrete element method simulation. The effective mass of particulate beds in the presence of the harmonic resonance was measured from two transfer functions: the acceleration transmissibility and the apparent mass. Experimental effective mass data for single component _ systems conformed to values based upon Rayleigh's energy method. When applying this technique to binary systems with various mixing situations, there appeared a significant effect of mixing quality upon the effective mass. The effective mass indicates not only the deviation from an ideal mix, but also the direction of segregation. The use of the apparent mass can offer rapid, convenient and reliable measurement to determine the dynamic properties of loosely packed beds, which has not been possible using previous methods. The longitudinal elastic modulus of the bed was calculated from the data via the wave equation. A substantial change in elasticity was detected with changes of packing states. It was clarified that the elasticity" of packed beds conforms to the fourth power scaling law. The applicability of the apparent mass data for detecting the density homogeneity and the mixing quality of mixtures was successfully demonstrated. There is great potential for use of these techniques in industrial situattonsas off-line and/or on-line measurement methods.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.518737  DOI: Not available
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