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Lang visning: Alle   Refleksion   Internt-faglige   Fri

Internt-fagligt, 1. modul, 2008/09, id:259
Vejleder:Tage Emil Christensen
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Abstract
English abstract
This project examines measurements of the shearmodulus by the piezoelectricity shear gauge, developed by the research group "Glass and Time" at Roskilde University ]Christensen og Olsen, 1995]. In the calculations used so far [Christensen og Olsen, 1995], it is assumed that the liquid will contract towards the center, as the temperatur declines. This assumption is not necessarily correct, since the liquid at lower temperatures will be more viscous, and thus flowing slover in the transducer. As the liquid gets colder, it will contract. It will thus pull in the piezoelektric disc, and the disc will therefore bend. Then the liquid will flow towards the center, and the disk will return to its initial position, where transducer and the liquid will be in equilibrium. The time it takes for the system to reach equilibrium is dependent on the viscosity. We have thus ezamined the displacement of the piwzoelectric disk from its initial position as a function of time and temperature. Then we have calculated the significance for the calculation of the shearmodulus, and thus discussed the relevance of the reults for the experimentel method. In the project a model for the displacement of the liquid and the piezoelektric disc as a function of temperature and time is produced. We have concluded that there must be a change of calculations method at the temperature [T-anneal] which is 25-20 degrees above the glass transition temperature. In measurements above [T-anneal] the liquid will have tome to reach the center, thus the assumption used up until today is true. When measurements are made below [T-anneal] the liquid to contract by bending the disks downwards and the height of the liquid layer will change.

Database opslag den: 20-11-2017