Moiré Interferometry Experimental Technique And Image Processing Method For PZT Material

Piezoelectric ceramic structures have been widely used in military and civil industries as well as in scientific researches. In these practical applications, there are some mechanical problems which desiderate experimental studies by means of sensitive, non-contact and whole-field measurement techniques. Meanwhile, as a rapidly developing technique of photomechanics, moiré interferometry has attracted attention for its advantages of high sensitivity, excellent contrast, noncontact, real time, whole field, etc. Therefore, some actual piezoelectric ceramic structures are tested by moiré interferometry experiments in this thesis. For improving the experimental method, a set of moiré interferometry image-processing software is firstly exploited. Then a new phase-unwrapping method RIPI is brought forward. Finally, the experimental technique incorporating silicon rubber specimen grating with insulated-layers is set up. As to low-quality experimental image, this thesis firstly analyzes, discusses and integrates most of the commonly used methods and techniques in fringe-images processing, and then exploits a set of moiré interferometry image-processing software. This software possesses such functions as read/write, interferometric fringe processing, phase extraction and strain evaluation. And it can be independently used to achieve the data for analyzing during the whole process from the Moiré interferometry image.Additionally, a new phase unwrapping method RIPI is proposed for solving the problems of "line-draw" or losing of useful data while phase unwrapping. Firstly, the three-step practical algorithm of RIPI is given; secondly, the principle of prefix traversal of expression tree in data structures is introduced; finally, the idea of regional integral is presented. Results show that RIPI can be effectual used in processing of the moiré interferometry images especially those of low quality.Furthermore, the experimental technique incorporating silicon rubber specimen grating with insulated-layers is set up for settling the problems of high-voltage insulation in the piezoelectric ceramic experiments. It is proved that cooperating with the moiré interferometry image-processing software this technique can be applied for whole-field measurement of piezoelectric ceramic structures with enough reliability and validity. At the last of this thesis, the intensity and geometrical optimization of a practical multilayer piezoelectric ceramic displacement actuator is analyzed basing on the numerical and experimental results. Results present that the high stress concentration caused by non-uniform electric field near the edge of the internal electrode is the major affecting factor inducing fracture and damage of the structures. It is also shown that the strength and reliability of multilayer piezoelectric structures may be significantly enhanced through the geometrical optimization by changing the optimized angle between 110?and 125?, with almost the same simplicity of the structure and feasible in the manufacturing process but without losing structural functions.