新型轻质复合材料夹芯结构的振动阻尼特性研究

发布时间：2018-01-05 22:21

本文关键词：新型轻质复合材料夹芯结构的振动阻尼特性研究　出处：《哈尔滨工业大学》2017年博士论文　论文类型：学位论文

【摘要】：作为新一代先进轻质超强韧结构材料,复合材料格栅和点阵夹芯结构受到了国内外众多学者的广泛关注。目前关于该类结构材料设计制备以及相关力学性能的研究已取得了大量研究成果。然而对于该类结构振动阻尼性能的研究则处于起步阶段。研制兼具优异力学性能和高阻尼性能的多功能复合材料及结构是当前轻质结构减振降噪研究的关键课题之一。本文基于结构阻尼一体化技术,设计并制备兼具结构承载功能和阻尼减振功能的新型轻质混杂复合材料点阵和波纹夹芯板壳结构,通过数值模拟、理论分析和试验表征的方法研究其固有振动特性、阻尼耗能机理及缺陷敏感性,并将本文研究的各类混杂复合材料夹芯结构的相关性能绘制到Lakes材料的模量-阻尼性能图中,进一步补充和完善该性能图,为设计新型结构阻尼一体化结构材料提供参考。主要包括以下内容:首先采用模压一次成型法制备了上下面板内含粘弹性阻尼层的混杂复合材料点阵夹芯板结构,通过模态试验研究其固有振动特性和阻尼性能。基于模态应变能法,采用数值方法预报结构的固有频率和阻尼损耗因子,通过分析阻尼贡献因子的变化规律揭示其阻尼耗能机理。讨论了纤维铺层角度、阻尼层厚度等因素对结构固有振动特性的影响。结果表明,相较于复合材料点阵夹芯结构,混杂复合材料点阵夹芯结构在不明显改变结构固有频率的同时能显著提高结构的阻尼损耗因子,降低其共振幅值。其次将点阵平板结构拓展到曲面结构,采用模压二次成型法制备复合材料金字塔点阵夹芯圆柱壳结构。采用Reissner-Mindlin一阶剪切理论,数值仿真和模态试验表征相结合的方法研究自由边界条件下,全碳纤维,全玻璃纤维和混杂纤维三种不同纤维配置的复合材料点阵夹芯圆柱壳的固有振动阻尼特性,并揭示其阻尼耗能机理。讨论了纤维铺设角度对结构固有频率和阻尼损耗因子的影响。理论分析、数值计算和试验结果良好的一致性验证了预报模型的有效性。相较于点阵夹芯平板结构,点阵夹芯圆柱壳表现出明显不同的固有振动阻尼特性和变化规律。再者考虑芯子增强方向对结构固有振动特性的影响,通过试验和数值方法系统地研究了复合材料纵向和环向波纹夹芯圆柱壳结构的固有振动特性和阻尼性能。探讨了波纹倾角,夹芯高度,芯子拓扑构型等因素对结构固有振动特性的影响。研究结果表明,在面板厚度和芯子相对密度相等的情况下,环向波纹夹芯圆柱壳的固有频率和阻尼损耗因子要高于纵向波纹夹芯圆柱壳,且纵向波纹夹芯圆柱壳要比环向波纹夹芯圆柱壳对结构几何参数的变化更敏感。参数研究的结果对该类曲面夹芯结构的动力学性能设计具有重要的指导意义。然后考虑结构质量的影响,采用试验和数值模拟相结合的方法系统地研究不同阻尼配置的混杂型复合材料点阵夹芯板结构的振动特性和阻尼性能,综合考虑了结构的刚度效率,阻尼效率和综合效率。将平板结构拓展到曲面壳结构,进一步修正和完善Lakes材料的模量-阻尼性能图。结果显示,添加阻尼材料能显著提高结构的阻尼效率,有效抑制结构的振动响应,但是也伴随着刚度效率不同程度的下降。在众多的阻尼配置方案中,芯子孔穴填充聚氨酯泡沫的点阵夹芯结构能获得最高的综合效率。采用局部阻尼约束方法,基于有限元模态应变能法进一步优化结构的阻尼效率是可行的。最后采用模态试验结合数值模拟的方法对自由边界条件下,面芯脱粘,杆件缺失,面板起皱和面板搭接补强等含不同损伤类型的复合材料点阵夹芯曲面壳结构进行了缺陷敏感性分析,并讨论了损伤类型,损伤程度,损伤位置和形式等因素对结构模态参数的影响。结果发现,损伤缺陷的存在会导致结构各阶固有频率不同程度的下降,且结构第一阶固有频率对损伤缺陷更敏感,相对偏差最大。同时还发现,结构阻尼损耗因子比固有频率的对损伤缺陷更加敏感,缺陷的引入会增加结构的阻尼耗能,从而导致结构频响幅值不同程度的下降。参数化研究得到了一些规律性结果,为下一步开展对该类结构的的无损检测和损伤缺陷定位研究打下基础。
[Abstract]:As a new generation of advanced ultra strong lightweight structural materials, composite grid and lattice sandwich structure has been widely concerned by many scholars at home and abroad. At present about the structure design and preparation of materials mechanical properties have made a lot of research results. But the research on the damping performance of the structure vibration is in the initial stage. The research and development of multifunctional composite materials and structure with good mechanical properties and high damping properties is one of the key topics in the current research on the noise reduction of vibration light structure. In this paper, the structural damping integration technique based on the design and preparation of both new lightweight structure bearing function and damping function of hybrid composite lattice and corrugated sandwich plate structure, through numerical simulation study on the inherent vibration characteristics, methods of theoretical analysis and experimental characterization of the damping mechanism and defect sensitivity, and This paper studies the properties of all kinds of hybrid composite sandwich structure is drawn to the Lakes material modulus and damping properties of the figure, further complement and improve the performance, to provide reference for the design of new structural damping material. The integrated structure mainly includes the following contents: firstly, forming a prepared hybrid composite lattice sandwich plate structure the lower panel with viscoelastic damping layer is molded, on its natural vibration and damping properties by modal test. Based on modal strain energy method, numerical method is adopted to forecast the structure of the natural frequency and the damping loss factor, through the analysis of the change of the damping contribution factor to reveal the damping mechanism. The angle of fiber layer. Influence of damping layer thickness on the structure vibration characteristic. The results show that, compared with the composite sandwich structure, hybrid composite material. In the array sandwich structure does not significantly alter the natural frequency of the structure at the same time can significantly improve the damping loss factor of the structure, reduce the resonance amplitude. Then the lattice plate structure to surface structure by pressing two molding composite materials prepared by Pyramid lattice sandwich cylindrical shell structure. Using Reissner-Mindlin method to study the first-order shear deformation theory, free boundary condition numerical simulation and experimental modal characterization of combination, full of carbon fiber, glass fiber and hybrid fiber with three different fiber configuration of composite lattice truss core sandwich cylindrical shell vibration damping characteristics, and reveals its damping mechanism. The fiber laying angle on the impact of structural natural frequency and damping loss factor of the theory. Analysis, numerical calculation and experimental results agree well validated prediction model. Compared to the lattice sandwich plate structure, point array Sandwich cylindrical shell exhibit significantly different natural vibration damping characteristics and variation. And considering the influence of enhanced core direction on the structural natural vibration characteristics, through experiments and numerical method to study the composite longitudinal and circumferential corrugated sandwich cylindrical shell structure has characteristics of damping and vibration. The corrugated inclination angle, discusses the sandwich influence of core height, topology and other factors on the natural vibration characteristics of the structure. The results show that the panel thickness and the relative density of the core under the condition of the same circumferential corrugated sandwich cylindrical shell and the natural frequency and damping factor is higher than that of vertical corrugated sandwich cylindrical shell, and the longitudinal corrugated sandwich cylindrical shell than circumferential corrugated sandwich the change of geometric parameters of cylindrical shell structure of the more sensitive parameters. Research results have an important means on the dynamic performance of the surface of the sandwich structure design The guiding significance. And then considering the influence of structure quality, vibration and damping performance by combining experimental and numerical simulations of different damping system configuration of the hybrid composite sandwich plate structure, considering the stiffness of the structure damping efficiency, efficiency and comprehensive efficiency. The flat structures to the shell structure further, revise and improve the Lakes material modulus and damping properties of graphs. The results show that adding damping materials can significantly improve the efficiency of the damping structure, effectively suppress the vibration response of structure, but also with the stiffness efficiency decreased. In the damping scheme, the lattice sandwich structure core cavity filled polyurethane foam to get the highest comprehensive efficiency. The local damping constraint method, and further optimize the structure damping efficiency method is feasible based on the finite element modal strain energy Finally, numerical simulation method. The modal test of free boundary conditions, face core debond, rod missing, wrinkling and panel reinforcement lap panel containing different damage types of composite sandwich shell structure of the defect sensitivity analysis, and discusses the types of injury, damage degree, damage location effect parameters and the form factors of the structural modal parameters. The results showed that the damage defects will lead to the decline of structural frequencies in different degree, and the first order natural frequency of the structure damage is more sensitive, the maximum relative deviation. It is also found that the structure damping loss factor is more sensitive than the natural frequency of defect, defect the increase of damping energy dissipation structure, resulting in the structure of frequency response amplitude decreased in different degrees. The parametric study obtained some regularity results for the next step to carry out the The research of nondestructive testing and damage defect location of the class structure is the basis.

【学位授予单位】：哈尔滨工业大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TB303

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