This monograph consists of investigation results obtained on the new theoretically well-grounded method for the total set of the compatible material constants for different piezoceramics. With this aim, there were carried out theoretical and experimental analysis, and various oscillation modes of electroelastic bars and plates were identified. Moreover, the physical and geometrical restrictions on the sample form were stated by using modified method of definition of the piezomodule d33 in quasistatic regime. These limitations allowed the authors to calculate the valid values of d33 for various piezoceramic families. By this, the boundaries of application of the above methods are discussed in this book. The results of identification of the various oscillation modes for bars and plates, and also the method and algorithm of the definition of total set of compatible material constants may significantly help in the development of the computation methods for characteristics of piezocomposite materials for force piezoactuators. One of the approaches in order to achieve this aim consists of practice forms of maximum displacements that could be created by using the stiffness matrices of composite based on the calculation algorithm of total set of the compatible piezoceramic material constants. Moreover, above modified algorithm may be used for research and development of new composites, in particular polymer-composite materials. This book is addressed to students, post-graduate students and specialists, taking part in the development, preparation and researching new materials and devices on their base.