Thermal Shock Strength of a Semi-infinite Piezoelectric Medium

This paper considers the mechanical problem of a semi-infinite piezoelectric medium under sudden thermal load. The medium contains an electrically conducting crack perpendicular to its surface. The transient stresses and electric fields in an uncracked medium are calculated first. Then, these stresses and electric fields are used as the crack surface traction and electric field loads with opposite signs to formulate the mixed boundary value problem. Numerical results for the stress and electric field intensity factors are calculated as a function of normalized time and crack size. Crack propagation behavior is discussed. The parameters that control the transient thermal stress and electric fields are also identified. The maximum thermal shock strength that the material can sustain without catastrophic failure is established according to two distinct criteria: (i) maximum local tensile stress equals the tensile strength of the medium, and (ii) maximum stress intensity factor for the preexisting representative crack equals the fracture toughness of the medium. The results show that the influence of the piezoelectric effects on the thermal stress intensity factor is insignificant.