The Study On Model Analysis Of Thin Plate Based On Electronic Speckle Pattern Interferometry

Electronic Speckle Pattern Interferometry is a high precision, full-field and realtime technology, which is widely used in measurement of the deformation caused byall kinds of loading. The measurement of deformation in vibration using ESPI is aresearch focus in recent years. Thin plate structure is easily deformed caused byexternal vibration source. So the investigation of thin plate’s resonance is verynecessary in the field of machining operation. In this thesis, we discuss theory andapplication of the Amplitude-Fluctuation ESPI. Then we investigate the application ofAF-ESPI on resonant model analysis of thin plate. The AF-ESPI experiment system isalso set up.The main work listed as following is completed in this thesis:1. Firstly we introduce and analyze measurement principle of AF-ESPI. UsingRayleigh-Ritz method we study resonant model of thin square plate with threedifferent types of boundary conditions: the bottom was clamped (CFFF), two oppositeedges clamped and the other two edges free (CFCF), all edges completely clamped(CCCC). The resonant frequencies and model shape of the first eight orders arecalculated through Matlab in this paper, and we analyze these results in detail. Finallythe distribution of speckled resonant fringes is obtained using deflection of thin platecombing with theoretical intensity of resonant fringes.2. The experimental system is designed and analyzed. We design large areauniform light source and build optical beam path; we design an embedded sinusoidalsignal vibrating source based on STM32chip and DDS technique, which can outputthe signal with0~10MHz frequency; we design software of control part, imagecapturing part and HMI part using C/C++language.3. Using AF-ESPI system we measure the resonant model of thin plate with threedifferent boundary conditions: CFFF, CFCF and CCCC. We also measure resonantfrequencies and resonant speckled interferometer fringes. We compare measuringresults with theoretical results and ANSYS results, and relative errors are given.4. We proposed a new method to calculate real deformation of thin plate atresonant model. This new method combines resonant speckled fringes with theoreticaldeflection; we extract the distance of fringes from one single speckled pattern, and calculate real deformation combing with theoretical deflection equations. In order toverify the precision of this method, we design several experiments. We capture severalfringes under different excited voltage. Then real deformation in resonant model canbe calculated using this method. Finally the error between the measuring result andcalculated results are calculated.