This book presents new approaches to R&D of piezoelectric actuators and generators of different types based on established, original constructions and contemporary research into framework of theoretical, experimental, and numerical methods of physics, mechanics, and materials science. Improved technical solutions incorporated into the devices demonstrate high output values of voltage and power, allowing application of the goods in various areas of energy harvesting. The book is divided into seven chapters, each presenting main results of the chapter, along with a brief exposition of novel findings from around the world proving context for the author results. It presents particular results of the Soviet and Russian schools of Mechanics and Material Sciences not previously available outside of Russia.