This paper derives a general solution of the three-dimensional equations of transversely isotropic piezothermoelastic materials (crystal class, 6 mm). Two displacement functions are first introduced to simplify the basic equations and a general solution is then derived using the operator theory. For the static case, the proposed general solution is very simple in form and can be used easily in certain boundary value problems. An illustrative example is given in the paper by considering the symmetric crack problem of an arbitrary temperature applied over the faces of a flat crack in an infinite space. The governing integro-differential equations of the problem are derived. It is found that exact expressions for the piezothermoelastic field for a penny-shaped crack subject to a uniform temperature can be obtained in terms of elementary functions. *[S0021-8936(00)01704-9]*

*Theory of Thermoelasticity With Applications*, Sijthoff and Noordhoff, Alpen aan den Rijn, The Netherlands.

*Applications of Potential Theory in Mechanics: A Selection of New Results*, Kluwer Academic Publishers, The Netherlands.

*Linear Piezoelectric Plate Vibrations*, Plenum Press, New York.

*Mixed Boundary Value Problems in Potential Theory*, North-Holland, Amsterdam.

*Crack Problems in the Classical Theory of Elasticity*, John Wiley and Sons, New York.