The Study On Mechanical Properties Of Thin Rectangular Plate Based On Electronic Speckle Pattern Interferometry

Thin plate structure is one of the most common structural elements in aeronautic and aerospace engineering,civil engineering,mechanical engineering,marine engineering,and so on.Its dynamic response has received wide attention from many scholars.The experimental study on the mechanical properties of thin plate can observe the mechanical response of the material under different working conditions,reveal its deformation characteristics and vibration mechanism,which is of great significance for the mechanical design and manufacture,and also provides a solid foundation for the establishment of a correct mathematical model.Electronic speckle pattern interferometry(ESPI)technique is a real-time,full-field,high precision and non-contact technology,which has become a research focus on the measurement of deformation in vibration in recent years.In this thesis,the mechanical characteristics of homogeneous rectangular aluminum plates and the honeycomb sandwich plates are investigated by using ESPI technique and the main contents are as follow:(1)The measurement principles of several ESPI methods are introduced in detail,and the ESPI experimental system is designed and set up.Based on first kind zero-order Bessel function,the method of calculating the fringe displacement is given.The energy method is used to solve the thin plate vibration problem.(2)The resonant deflection of the thin rectangular plate under the boundary conditions of cantilever(CFFF)and two opposite edges clamped(CFCF)is discussed theoretically.The corresponding intensity distribution of resonant fringe pattern modulated by the first kind zeroorder Bessel function is obtained by using the dynamic deflection of the thin plate and the principle of electronic speckle pattern interferometry.On this basis,the primary resonance of rectangular aluminum plate under these two kinds of boundary conditions is studied experimentally using the ESPI method.The experimental results are in good agreement with the finite element results and theoretical calculations.Moreover,the influence of root-silt on the resonance frequency and mode shape of the aluminum plate is studied.Also,the vibration of intact and imperfect honeycomb sandwich plates are studied experimentally,and the influence of the excitation position on the mode shape is analyzed.(3)Using the ESPI experimental system,the super-harmonic resonance of homogeneous rectangular thin plate under two kinds of boundary conditions is studied experimentally.The influence of excitation frequency and excitation voltage on mode shape is analyzed.Also,the experimental study on the super-harmonic resonance of the root-silt plate is conducted.The experimental results show that both the intact plate and the root-silt plate exhibit a strong odd multiple frequency response.Moreover,the root-slit plate also exhibits a strong even multiple frequency response,while no obvious even multiple frequency response is observed for the intact aluminum plates used in the experiment.The experiment results also show that when the cantilever aluminum plate is subjected to nonlinear vibration,its higher-harmonic resonance amplitude will fluctuate.