## 1 Introduction  
Benefiting from the high damping performance, viscoelastic materials have been widely utilized in aerospace and vehicle transport industries. The dynamic mechanical properties of viscoelastic materials such as loss factor, Young's modulus and shear modulus are essential parameters in the investigations of structural vibration and acoustic. The measurement of dynamic parameters of viscoelastic materials have attracted much attention. In the area of mechanical vibration and shock, traditional test methods to determine the dynamic mechanical properties of viscoelastic materials include the resonance method, the cantilever shear beam method, the dynamic stiffness method [1] as well as the vibrating cantilever beam test method (VCBTM) [2], etc. Specifically, to measure the damping properties of materials, the system damping of structures are usually tested firstly. Methods for the determination and identification of the damping parameter include the decay rate method [3; 4], the half-power bandwidth method [5], the power input method [6; 7], the circle-fit method [8] and the integral method [9], etc. Viscoelastic materials are usually non-self-supporting and are embedded into composite structures. Hence determining the mechanical parameters of viscoelastic materials becomes the inverse problem of calculating the dynamic characteristics of composite configurations. Among the dynamic research on the composite structures, [PERSON] and [PERSON] [10; 11] firstly accomplished the damping analysis of constrained-layer damped structures employing the complex stiffness method as well as the strain energy method. Base on the complex stiffness method, [PERSON] and [PERSON] [12] evaluated the loss factor and resonant frequency of multilayered structural composites with viscoelastic materials. The modal strain energy method (MSEM) is nowadays widely used to investigate the vibration characteristics of composite structures [13; 14], yet it's hard to apply the MSEM in the damping identification of materials. Recently some new methods have been presented to determine the damping and stiffness characteristics of structures. The force analysis technique was used by [PERSON] et al. [15] to identify the stiffness and damping properties of both homogenous and heterogeneous structures, establishing a straight forward relationship between the material properties and displacement field. The complex wavenumber method was developed by [PERSON] and [PERSON] [16] to estimate frequency-dependent loss factor of a beam with arbitrary transient loading. Subsequently, [PERSON] et al. [17] employed this method to determine structural damping property over discrete but regularly spaced frequency with the experimental validation based on cantilever beam test. The wavenumber method was also implemented by [PERSON] et al. [18] to obtain effective sandwich structural properties and identify the equivalent models. The displacement field method was developed by [PERSON] et al. [19] to estimate the loss factor of two-dimensional orthotropic structures based on a scanning laser vibrometer measurement. The inverse identification approach was implemented by [PERSON] et al. [20] to characterize the viscoelastic layers in sandwich panels and was used by [PERSON] et al. [21] to evaluate the mechanical parameters of viscoelastic materials. Among the various test methods, the vibrating cantilever beam test method (VCBTM) has been widely used to determine materials' dynamic mechanical properties because of its simple and feasible maneuverability. It is remarkable that test methods based on microscale cantilevers are also widely utilized to extract the mechanical properties of materials and structures in small dimensions. [PERSON] et al. [22] determined the [PERSON]'s moduli of amorphous Cu-Zr thin films by force-deflection measurements of microscale cantilevers on the basis of atomic force microscope (AFM) technique. [PERSON] et al.