## 1 Introduction
[PERSON]'s and [PERSON]'s methods are not limited to the identification focused on the resonant frequency points, and thus, this work represents great progress in the identification study. However, the aforementioned researches still have some problems. First, most identifications are based on the cantilever beam specimen. Considering the variation in their polymeric composition and their mechanical states, viscoelastic materials will exhibit different mechanical characteristics. Therefore, the identification results of the beam specimen could not fully meet the requirements of other structures, such as the requirements of the dynamic analysis of a plate specimen. Moreover, most identification studies obtained the frequency response function of the composite beam by the hammer test and then inversely identified the mechanical parameters of viscoelastic material. While the hammer test involves the problem that the excitation position is difficult to accurately determine, the inaccurate excitation point may affect the identification accuracy of the parameters of the viscoelastic material. Finally, for all the aforementioned researches, only the viscoelastic material damping is contained in the analysis model, and the clamped damping of the specimen and the air damping (here both defined as the remaining equivalent viscous damping) are usually neglected. To the authors' knowledge, such an analysis model will result in the measured damping always being greater than the calculated value, which may interfere with the identification accuracies of viscoelastic material parameters. In order to obtain the parameter values of viscoelastic materials accurately and efficiently, a new identification method needs to be developed. Based on the aforementioned researches, this paper presents an inverse method to identify the mechanical parameters of a viscoelastic core layer based on the frequency vibration response. The features of the presented method are as follows: (1) the cantilever plate-shaped specimen attached with CLD was chosen to carry out the identification of the viscoelastic material parameters; (2) both the material damping and the remaining equivalent viscous damping were considered in the created analysis model; (3) the data at the resonance point and non-resonance point can both be used to identify the viscoelastic parameter; and (4) the frequency responses obtained by sweeping under base excitation were mainly used to identify the parameters. This study is organized as follows. In Section 2, the identification principle of the proposed method is given. In Section 3, both the viscoelasticmaterial damping and the remaining equivalent viscous damping are considered in the analysis model. Meanwhile, an example is presented to illustrate the importance of introducing the two kinds of damping into the analysis model. In Section 4, the formula of the matching calculation between the theoretical analysis and experiment is derived, based on the sensitivity method. In Section 5, a CLD aluminum plate with a ZN_1 viscoelastic core layer is chosen to demonstrate the proposed method and the fractional derivative model is identified. The rationality of the obtained identification results is verified by comparing the calculated and measured frequency vibration response. Some conclusions are listed in Section 6.