Research On Key Technology Of Deformation Measurement Based On Electronic Speckle Pattern Interferometry

There is a growing demand for three-dimensional deformation measurement in manufacturing industry,such as material science,vehicle and ship design,aerospace,engineering construction,steel manufacture and so on.Electronic Speckle Pattern Interferometry Technology(ESPI)is a full-field noncontact high accuracy optical measurement technology,which is being widely used for the measurement of strain,stress,displacement and defect of components and structures.The key of ESPI process is to extract the phase from intensity images through a series of analysis and processing.However,the correspondence between phase and deformation in three-dimensional reconstruction is not fully researched.For example,the synchronization problems of real-time measurement,the matching algorithm of different sensitivity results.More and more attention should be paid to the improvement of ESPI,it will take an important place in fulfilling the real-time and high-precision requirements.Relatively few studies have investigated the sensitivity and matching problem in ESPI.This paper presents a spatial phase-shift electronic speckle patterns interferometry system,with the capability of measuring three-dimensional deformations under a dynamic loading condition simultaneously using multiple cameras.An improved spatial phase shift algorithm is applied to achieve measurement under dynamic loading.The consistency of different cameras is achieved using DIC technology.Calibration and calculation programs are compiled to make sure each subset on the measuring surface is uniform.ESPI and DIC techniques are combined to provide a direct measurement of the three-dimensional deformation of the entire surface area simultaneously.The high-precision equipment of three-dimensional ESPI for three-dimensional deformation measurement is developed.Meanwhile,the software of phase calculation for three-dimensional measurement is programmed.The main research contents and achievements of this thesis are as follows:1)The conventional temporal-phase shift method is not suite for dynamic testing,a spatial carrier phase extraction algorithm based on deflection angle is introduced to achieve dynamic phase testing.The comparision results is used for verifing the correctness and feasibility of the algorithm.2)A simple and practical three-dimensional synchronous deformation measurement method is proposed based on different sensitive directions.The synchronization,real-time and dynamic performance of the measurement is achieved by the combination of ESPI and DIC techniques.3)Based on the iterative closest point(ICP)algorithm,we proposed a rigid body movement elimination method with boundary conditions.According to the phase information measured by ESPI,the trust region is selected due to the phase value.4)Based on the uncertainty theory and method,the uncertainty analysis of ESPI is carried out.The measurement uncertainty model is established,and the specific evaluation process is given.Meanwhile,the error analysis of the measurement system is done.The influence of the observation direction on the measurement results is deduced.The effects of imaging distortion and measurement environment of the system are also evaluated.5)The three-dimensional deformation measurement of ESPI is established,and the software based on the setup is developed.The application result and validation experiment are presented.