Strain fluctuation in a non-isothermal solid

In this thesis we use nonequilibrium thermodynamics tools in order to investigate spontaneous vibration fluctuations of continuous, elastic, conductive and dissipative solids in and out of equilibrium states. In particular we want to advance with respect to previous theoretical models, based on global equilibrium thermodynamics, and to obtain the strain fluctuations of displacement under the assumption of local equilibrium. We develop explicit calculations for 1-dimensional solids under constant thermal gradients. Ultimate goal of the research which inspires this work, is the assessment of thermal noise of Advanced VIRGO, Advanced LIGO and next generation of gravitational wave interferometers under realistic nonequilibrium assumptions.