The laser linear scanning method is proposed to measure the modal shape of fiber-reinforced composite thin plate with high efficiency and precision. First, by establishing the laser scanning frame model of the composite plate, the corresponding extraction principle of modal shape data and laser scanning rate selection criterion are explained in detail to clarify the theoretical principle of laser linear scanning method. The corresponding test procedure of modal shape, drawing method from the shape scanning data, and control method of the constant laser scanning rate are also proposed based on the developed laser linear scanning system. Then, a TC300 carbon fiber/resin composite thin plate is taken as a research object to verify the effectiveness and reliability of such a method, through comparing the results obtained by the traditional experimental modal method and finite element method. Moreover, the influences of constraint boundary condition, excitation level, laser scanning rate, scanning spacing, scanning path mode, the fiber angles, and fiber material damage on modal shape results are also discussed. It has been found that laser linear scanning method can improve test efficiency of modal shape of the composite plate with high preciseness. Except for scanning path mode, the other parameters have a major impact on each shape morphology, and their effects can be quantitatively analyzed by identifying the positions and clarity of nodal lines of each modal shape. Especially, the high-density modal shape results and their equal amplitude lines in different projection views can be used to determine whether or not the composite plate is damaged as well as its damaged degrees.

In this research, the characterization test on nonlinear vibration of a fibre-reinforced composite thin plate is studied. First, in order to improve the efficiency and precision of the test, a laser scanning vibration system is designed and developed. Then, test methods and procedures of the harmonic distortion and nonlinear time-varying damping of such thin plates are proposed from the time-domain perspective. Corresponding test methods and procedures of nonlinear vibration properties such as the hard/soft stiffness and amplitude-dependent damping are also presented from the frequency-domain perspective. Finally, the TC500 carbon fibre/resin composite plate is selected as an example for the research to carry out a case study. Potential nonlinear vibration phenomena of such plates are characterized by the proposed test methods. It has been proved that the related test system and techniques adopted in this paper can provide an important reference for the establishment of the nonlinear vibration test methodology of fibre-reinforced composite structures.

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：This research studies damage location detection of fiber-reinforced composite thin plate based on laser scanning method. The laser scanning frame model of the composite plate is established, and when the extraction principle of modal shape data is illustrated, two-dimensional five-spot-tripling surface smoothing method is proposed, so that a quantitative index for damage location detection of fiber-reinforced composite thin plate, i.e., the damage location index can be derived. The Matlab calculation program is written, and the specific damage location detection procedures of composite plate based on laser scanning method are also proposed. T300 fiber/epoxy composite plate is taken as a study object, and damage detection experiment is performed based on the established laser scanning vibration testing system. It has been proved that the above method can detect fiber breakage position of such composite plate with high accuracy, and this method and the related experimental system can provide a new idea for damage detection and identification of composite structures. Key words：fiber-reinforced composite plate；two-dimensional five-spot-tripling surface smoothing method；damage location detection；laser linear scanning；experimental study 0 前言* 纤维增强复合材料比强度高、比模量高、热稳 定性好， 还有一定的阻尼减振能力。 目前， 以 TC300、 TC500 和 TC800 等为代表的先进碳纤维/树脂基复 合材料正在被越来越多地应用于航空、航天、汽车

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