Theory of Buckling of a Porous Slab and Its Thermoelastic Analogy

A theory is developed for the buckling of a fluid-saturated porous slab under axial compression. The problem is discussed in the context of the thermodynamics of irreversible processes. It is shown that there is a range of compressive loads, between a lower and upper critical value, for which the slab exhibits creep buckling. The problem of folding instability of a porous layer embedded in a viscous or viscoelastic medium is also analyzed and the dominant wavelength is evaluated. Identical behavior is derived by analogy for a thermoelastic slab with a critical range between isothermal and adiabatic buckling. The theory is applicable to a large class of two-phase materials obeying the same thermodynamics. It also provides a simple analysis of thermoelastic damping of plates.