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系统推导了热压电力学的变分原理（非Gurtin型，也不含卷积）．若应用传统的拉氏乘子法，由于会出现临界变分现象，不能得到本文的结果．本文指出临界变分是拉氏乘子的固有特性，半反推法是克服临界变分的有效途径之一．应用半反推法，根据Chandrasekharaiah关于压电材料的广义线性热弹性理论，直接从控制方程及边初值条件，得到了经典意义上的一个耦合广义变分原理．本文的理论将给有限元方法、无单元方法及一些变分直接方法（如Ritz法、Trefftz法及Kantorovitch法等）提供严密的理论基础．
The system derives the principle of variational thermocompression (non-Gurtin type, nor convolution). If we use the traditional Laplace multiplier method, we can not get the result of this paper because of the phenomenon of critical variation. This paper points out that the critical variation is the intrinsic property of Laplace multiplier, and the semi-inverse method is one of the effective ways to overcome the critical variation. According to Chandrasekharaiah’s generalized linear thermoelastic theory of piezoelectric materials, a coupled generalized variational principle in the classical sense is derived directly from the governing equations and the initial conditions. The theory of this paper will provide a rigorous theoretical foundation for the finite element method, element-free method and some variational direct methods (such as Ritz method, Trefftz method and Kantorovitch method).