NEAR TIP STRESS INTENSITY FACTOR OF A SURFACE EDGE-CRACK IN PZT THIN FILMS WITH 90° DOMAIN SWITCHING DUE TO A THERMAL LOADING
(0) The methods of fracture mechanics can be applied to describe the extensionbehavior of a surface edge-crack,and the applied stress intensity factor (SIF)Kapp can be evaluated using the weight function method.However,a small scale 90°switching strain of fcrroelectric materials would contribute to the shielding SIF △K viathe body force under a thermal loading,and the △K is used to investigate switchingtoughening at the crack-tip.Choosing the appropriate weight functions,both of Kapp and△K can be integrated by the stress field and the body force induced by 90°switchingstrain centered at the crack-tip.Based on the small scale switching theory,the near tip SIFKtip can be obtained by the superposition of Kapp and △K.In this paper,the stressfields of a circular PZT thin film under thermal loading are calculated by using the finiteelement method via ANSYS software.Dependence of the SIFs on the following factors isinvestigated: the power density and irradiation time for the Gaussian source of acontinuous laser irradiation,crack length and initial poling angle.The results show thatwith increasing of q0 and t,Kapp is demonstrated to fhst increase and then decreasewith the propagating of crack.The △K decreases from positive to negative with theincrease of initial poling angle ranging from 0° to 90°,and the critical initial poling angleis 45°.The decrease of △K results in the weakening of Kttp.With certain initial polingdirections (45°＜φ ≤90°),PZT thin films are toughened by the domain switching area,whereas,with other directions,are weakened.It is revealed that the near tip SIF issignificantly affected by 90° domain switching under different initial poling angles.
B.Wu X.J.Zheng D.H.Li Y.C.Zhou
Faculty of Materials,Optoelectronics and Physics,Xiangtan University,Xiangtan,Hunan,411105,China Faculty of Materials,Optoelectronics and Physics,Xiangtan University,Xiangtan,Hunan,411105,China Key Faculty of Materials,Optoelectronics and Physics,Xiangtan University,Xiangtan,Hunan,411105,China Key
国际会议
第二届国际非均质材料力学会议(The Second International Conference on Heterogeneous Material Mechanics)
安徽黄山
英文
515-516
2008-06-03（万方平台首次上网日期，不代表论文的发表时间）