Thermoelastic fluctuations in solids

Adiabatic thermoelastic heating can be used to monitor stress fluctuations in solids. Previous Studies of the effects on the temperature fluctuations both of applied static stress and of the finite amplitude of the stress flu ctuations have used approximate theory. The present rigorous thermodynamic treatment distinguishes between adiabatic second-order derivatives needed f or finite amplitude and mixed derivatives needed for static applied stress. A detailed analysis is given for purely compressive stress. followed by co mputations for KCI, NaCl, Al, Cu, Ti, and the alloy Ti-6Al-4V. Additional t erms revealed by the new analysis prove to be substantial, including the di fference between the adiabatic and mixed derivatives. Revised forms are the n proposed for earlier approximations. For unidirectional stress, expressio ns are taken from an analysis given elsewhere: and Computations made for Al . Cot, Ti and Ti-6Al-4V, Corrections to earlier approximations are relative ly smaller than for compressive stress, and of opposite sign because the sh ear component of the unidirectional stress dominates the second order effec ts.