Today structural health monitoring is a widely developing field that enables real-time damage detection of engineering structures and elements. Monitoring is carried out using a set of sensors, most of which contain piezoelectric materials. So far the problem of crack resistance and lifetime estimation for polycrystalline piezoelectric materials has not been fully solved. The paper considers fundamentals of linear fracture electromechanics, fracture parameters and fracture criteria. The main difference from linear fracture mechanics is the need for taking into account relative permeability of media inside the crack gap and crack face Coulomb interaction . Different types of crack face boundary conditions and their numerical implementation were described. The paper presents the results of finite element modeling of the fracture toughness experiments conducted on the compact tension specimens under combined electromechanical loading. Different types of crack face boundary conditions and their influence on fracture toughness were analyzed and different fracture criteria were compared to the experimental data.