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Study on Detection of Structural Defects Based on DSSPI

Author: WangMin
Tutor: WangKaiFu
School: Nanjing University of Aeronautics and Astronautics
Course: Engineering Mechanics
Keywords: DSSPI Phase-shift inner defect testing elastic plate FEM gas pressure loading method
CLC: TH878
Type: Master's thesis
Year: 2011
Downloads: 37
Quote: 0
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Abstract


Defects of structures include inner defects and surface defects. Defects on the surface of structures are visible and easy to be detected, but inner ones are covered and hard to be found. Some detecting methods are widely used and have solved many problems, such as Magnetic particle Method, Eddy current Method, Ultrasonic method, X-Ray method,ete. But there is few reported literature about quantified researches on inner defects.The existence of small defect in struetures is a big hidden trouble for the safety,so a method that can be used to detect inner defects is concerned by many companies.In the view of Photo-Optic Mechanies, Elastic Mechanics, and FEM method, the deformation of inner defects in structures was studied based on DSSPI and Phase-Shift in this dissertation and some valuable results and conclusions were obtained.With DSSPI and Phase-Shift method,referring many relative literatures, we did some research on inner defects,designed a typical specimen used in the study and compared the strong point and weak point of each loading method.Gas pressure is a better load so we advanced the gas pressure method and design a new gas pressure loading device. carry out a series of experiments with DSSPI instrument and got lots of data.The research settled the base of further studies, and raised some suggestion to improve the experiment.The dissertation study an experimental technology which can be used to detect inner defects in structures.The specimen with defect is simulated with elastic sheet and its deformation under load is obtained.The study can be used to detect specimen whose thickness much less than specimen and defect diameter.We used the mechanieal mode, numerical simulation and experiment study in this dissertation, which made the study more effective. DSSPI method and phase-shift technique are used in the dissertation sueeessfully, and the deformation derivative of the defected specimen which is made of duralumin is detected. It proves that there is feasibility and advantage of DSSPI when it is used in inner defect detection. This study provides a new method that can detect inner defects and widen the application of DSSPI.

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CLC: > Industrial Technology > Machinery and Instrument Industry > Instruments, meters > Material testing machine and test equipment > Nondestructive flaw detector
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