However, the elastic modulus and loss factor of viscoelastic material usually change with frequency, which will cause difficulties in the calculation of structure dynamics.
但是，由于粘弹性材料的弹性模量和损耗因子往往随频率变化，对设计计算造成了一定的困难。
Frequency and loss factor are two important indices of dynamic property of composite structures, in which the viscoelastic material is sandwiched between the upper layer and the lower layer.
频率和损耗因子是粘弹性材料复合夹层结构的两个重要的动力特性指标。
The constant complex module of viscoelastic material is used to calculate the frequency and loss factor of the sandwich pate by the complex eigenvalue method.
粘弹性采用常复数模型，用求解复特征值的方法求得了其固有频率和损耗因子。
PAN L J, ZHANG B M, DAI F H. Loss factor of viscoelastic damping composite material under harmonic excitation [J]. Journal of Vibration and Shock, 2008, 27(2): 57-60.
[16]潘利剑，张博明，戴福洪。 简谐激励下共固化复合材料黏弹阻尼结构的损耗因子研究[J]。振动与冲击，2008，27（2）： 57-60。
PAN L J, ZHANG B M, DAI F H. Loss factor of viscoelastic damping composite material under harmonic excitation [J]. Journal of Vibration and Shock, 2008, 27(2): 57-60.
[16]潘利剑，张博明，戴福洪。 简谐激励下共固化复合材料黏弹阻尼结构的损耗因子研究[J]。振动与冲击，2008，27（2）： 57-60。
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