Effects Of Temperature Change On Damage Fields Of Thermopiezoelectric Materials

With the rapidly increasing use of piezoelectric materials in high-temperature environment, it is important to study the thermoelectroelastic coupling problems. In order to investigate the effect of temperature change on the damage fields of thermopiezoelectric materials, this thesis presented a static non-linear constitutive model, damage constitutive model. The finite element equations and its solution for the thermoelectroelastic coupling problem were then obtained by the virtual work principle. Finally, the damage fields near crack-tips in thermopiezoelectric plates and a three-point bending beam under different thermal loads were calculated as illustration examples. (1) Based on the damage constitutive theory presented by Yang, this thesis added a variable θto the constitutive relation and deduced the constitutive relation of thermopiezoelectric materials by means of the theorem of energy equivalence. The relationships of material constants between damaged and undamaged materials were also given. (2) Presented the finite element equations of steady temperature fields and the coupling problems. (3) As examples, the damage fields near central crack-tips in two kinds of thermo-piezo-electric plates were analyzed by using the above numerical method. The effects of temperature change on the damage fields were studied. At the same time, a three-point bending beam under different thermal loads was calculated. The damage curves and contours of damage fields ahead of the crack tip were also shown.