| With the development of science and technology, deformation measurement with higher precision is required. It is hard for the traditional measurement methods to meet the requirements.digital close-range photogrammetry (CRP), which is developed on the hybridization between the measurement theory and computer technology, is a valid measurement method for obtaining high-precision deformation. For the sake of the advantages of optical technology, digital CRP has such merits as non-contact, non-destruction after nearly two hundred years of development, especially, in recent decades. Nowadays, two-dimensional digital CRP has been matured enough to be employed widely in scientific research and construction projects, such as construction, biology, automobile industry, aerospace industry, disaster assessment, chemistry and archeology. Currently, the fundamental theory and application research of the three-dimensional digital CRP attract much attention. In using digital CRP, one or more video cameras or digital cameras are needed to acquire the digital images of an objective. Further, a relate software is used to process the images for finding out the high-precision deformation data of the objective. By the method, the three-dimensional deformation data can be obtained, e.g., the comparison between the coordinates of the observation points on the objective before and after deformation will find the deformation field of the objective. Compared with the traditional methods, digital CRP is operated easily with higher efficiency and precision.To obtain the compressive properties of a material, compression experiment is required. In traditional experiment, a specimen with the material is layout between two clamps on a universal testing machine, and the deformation of specimen under compressive loading is recorded. Finally, the compressive properties of the material in specimen are found using the deformation along compression and the load applied. It is known that the contact friction between the clamps and the specimen exists, which leads to the drum-shaped deformation of the specimen. Therefore, the compressive properties by the traditional measurement approach are not accurate enough. To improve the accuracy, a hybrid approach combining compression experiment, digital CRP and finite element analysis of specimen is proposed in this thesis. The main contents of the present work are as follows:First, accidents related to material damage in structure and the importance of structural deformation measurements are illustrated, research progress of the advantages and disadvantages on traditional measurement methods are reviewed and on structural deformation.Second, the development of close-range photogrammetry is summarized. The theories and applications of the methods, e.g., photogrammetry and laser scanning, are briefly introduced since the late1970s.Third, digital CRP is adopted into material mechanical experiments for measuring the deformation of specimens. The flowchart of the experiment is list.Fourth, the parameters of material compressive properties are modified by using the DCRP data and finite element methods.In experiments, camera Canon700D is employed to measure the rubber specimen photos before and after deformation; AutoCAD is used to extract the in-plane coordinates of the observation points on specimen; Isoparametric transformation method is presented to find the displacement of the observation points; Using the elastic modulus and Poisson’s ratio obtained by the testing machine software as the initial values of material parameters, the deformation of specimen is inversely analyzed by ANSYS, and iterative structural deformation analysis are carried out to modify the parameters. |
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