The Numerical Analysis Of Interfacial Fracture Behavior For Piezoelectric Composite Materials

Piezoelectric smart composite materials have special features in engineering applications, and it can control the deformation of the material which is attached to it by the input voltage. With this feature, the piezoelectric material is made into piezoelectric film pasted on the surface of the composite laminates to the control of the shape and layer interface fracture behavior of laminates. The composites have several advantages, such as high strength, light weight. However, because it is easy to produce damage, the piezoelectric film is added to the surface or between layers to play the role of sensors to detect damage.In this paper, on the basic of laminated composite plate finite element static analysis program system, the program system takes into account the piezoelectricity, and the introduction of interface cementation unit, in order to achieve the static analysis of the laminated composite plate structure with the surface paste of piezoelectric film, to carry out the numerical analysis of the interface fracture behavior. The programs in this paper are based on the finite element principle of piezoelectric composite materials, and through an improved cementation unit to connect the piezoelectric film and laminates. Then the equivalent internal force and equivalent bending moment are deduced by the piezoelectric film equivalent with the input voltage, and then they are converted into total equivalent moment and are put into the total load of laminated plates. Because the interface crack problem of piezoelectric smart composite material is usually caused by bending, through the analysis of two cases in this paper, piezoelectric composite finite element program for simple laminated plate bending drive and control the bending has a more good results.Meanwhile, during the manufacturing processing of piezoelectric film and laminated composite, due to the mismatch of the matrix composite materials and piezoelectric materials, the piezoelectric composite material could engender stress concentration resulting from small cracks during layers easily, as the cracks growth will lead to the failure of the whole structure. Through the analysis of interfacial stress displacement field of the piezoelectric smart composites, the performance of interface fracture with toughened layers is analyzed with the help of J integral method. By adding toughening layer between the piezoelectric film and the laminates, the strength of the interlayer can be enhanced, however, toughened layer of different material properties can have different results for the laminates containing interlayer crack. In this paper, we found a finite element model of piezoelectric composite materials including interlayer crack, using the equivalent integral method to calculate the J integral and crack tip stress of different types PZT patches and the different thickness and elastic modulus of toughening layer. The results show that J integral and the stress of mode I, II reduces with the toughening layer, and the J integral of mode II decreases more sharply than that of mode I.The work of this paper is supported by National Natural Science Foundation "The failure mechanism of smart composite structure considering interface damage"(NO.10872038) and Special funds for basic research and operating expenses of the Central Universities (NO.DUT11ZD(G)01).