基于振动梁法小弹性模量材料阻尼特性测试研究

摘要

The structural loss factor of the metal sandwich beam with a damping core can be determined by using the vibration beam test method. Then, the material loss factor of the damping layer can be calculated. But the present theoretical study shows that if the Young’s modulus of the damping layer material is lower than 10 MPa, the damping layer can be strongly and transversely compressed by the metal-layers under the external loading. This phenomenon breaks the assumption of the vibration beam method. Therefore, a method combining testing and simulation was used to obtain the material loss factors of three low Young’s modulus damping materials, HT 800, Regufoam 2000 and SR 450. Using the vibration beam method in the testing, the structural loss factor of the sandwich beam was obtained. Then, this factor was used as the target of the simulation. In the simulation, the finite element model of the sandwich beam was developed to calculate the structural loss factor. Then, by changing different input values of the material loss factor until the simulation output of the structural loss factor identifies that of the testing, the real value of the material loss factor could be obtained. This method provides a reference for determination of the material loss factors of low Young’s modulus damping materials.%振动梁法可以获取“金属层+阻尼层+金属层”三明治梁的结构损耗因子，进而求得阻尼材料的材料损耗因子。但是通过理论研究发现，当阻尼材料的弹性模量低于10 MPa时，在外载荷作用下，三明治梁的上下金属层对阻尼层产生明显的横向挤压，不满足振动梁法的理论假设。为此，提出一种仿真与试验相结合的方法获取了HT 800、Regufoam 2000和SR 450这三种小弹性模量阻尼材料的材料损耗因子。在试验部分，利用振动梁法获取三明治梁结构阻尼损耗因子，以此作为仿真中结构损耗因子的目标值。仿真部分，建立三明治梁有限元模型，通过不断改变材料损耗因子的输入值获取模型相应的结构损耗因子，直到仿真与试验结构损耗因子相等时，仿真中相应的材料损耗因子值即为小弹性模量阻尼材料损耗因子。该种测试方法为小弹性模态阻尼材料阻尼测试提供了参考。