不同老化状态黏弹夹层结构的模态分析

Modal analysis of viscoelastic sandwich structure with different aging states

黏弹夹层结构被广泛应用于机械设备的减振、降噪等方面,但在长期储存、运输和使用过程中,黏弹性材料会出现老化现象,致使黏弹夹层结构的服役性能退化,从而影响整个机械设备的性能和使用安全。因此,研究黏弹夹层结构的老化状态识别方法是工程实际的迫切需要。设计了黏弹夹层结构的实验装置,通过黏弹性材料的热氧加速老化实验获得了不同老化程度的试样,通过黏弹性材料的力学性能测试试验获得了不同老化程度下的性能指标;采用三维建模—导入—前处理方法建立了黏弹夹层结构的有限元模型,使用输入黏弹性材料不同参数的方式达成了等效模型不同老化状态的目的,完成了不同老化下结构的模态分析,建立了老化状态变化和固有频率变化之间的对应关系;通过脉冲激励实验验证了有限元模型的有效性。研究结果表明,建立的黏弹夹层结构的有限元模型能够反映其老化状态特性及其变化,可为其老化状态识别提供理论基础和先验知识。

Viscoelastic sandwich structure is widely used in sealing,vibration damping and noise reduction of mechanical equipment.However,there is aging phenomena of viscoelastic material in the process of long time storage,transportation and usage.The aging of viscoelastic material will result in the service performance degradation of viscoelastic sandwich structure,thus affect the performance and safe use of whole mechanical equipment.Therefore,it is greatly required of the engineering practice to research the aging state recognition method of viscoelastic sandwich structure.In this paper,the experimental device of typical viscoelastic sandwich structure was designed.The hot oxygen accelerated aging experiment of viscoelastic material was accomplished,and the specimens with different aging degrees were obtained.The mechanical property test of viscoelastic material was implemented,and the performance indexes under different aging degrees were obtained.By the 3D modeling-importing-preprocessing method,the finite element model of viscoelastic sandwich structure was established.By importing the different parameters of viscoelastic material,the equivalent models with different aging states was obtained.The finite element analysis of viscoelastic sandwich structure under different aging states was carried out,and the corresponding relations between aging state change and natural frequency change were built.Through impulse excitation experiment,the effectiveness of finite element model was verified.The research results show that the established finite element model of viscoelastic sandwich structure can reflect the structural aging state characteristics and its change,and can provide theoretical foundation and prior knowledge for the structural aging recognition.