在小变形线弹性理论的基础上,构造了阻尼夹层板单元。对三层板均采用M ind lin板单元,以各层的中面为坐标平面建立局部坐标系来建立有限元模型,芯层材料的粘弹性采用常复数模型。对其动态特性进行了有限元分析,采用求解复特征值的方法...在小变形线弹性理论的基础上,构造了阻尼夹层板单元。对三层板均采用M ind lin板单元,以各层的中面为坐标平面建立局部坐标系来建立有限元模型,芯层材料的粘弹性采用常复数模型。对其动态特性进行了有限元分析,采用求解复特征值的方法求得了其频率和损耗因子。在此基础上进行了详细的数值计算与分析,讨论了粘弹性阻尼层的厚度、模量、损耗因子对结构动力特性的影响,对结构的阻尼机理有了进一步理解,得到了一些有工程应用价值的结论。最后分别对单一铝板、自由阻尼层板和约束阻尼层板进行了模态实验,验证了理论计算的正确性。展开更多
随着工业化的发展,建筑结构逐渐轻量化,机械设备逐渐重型化、高效化,这使得机械设备高频扰力导致的结构振动问题越来越突出;为了减轻结构的高频受迫振动响应,可以在结构振动响应较大的位置安装高频高阻尼比的钢板夹层阻尼悬臂梁式调谐...随着工业化的发展,建筑结构逐渐轻量化,机械设备逐渐重型化、高效化,这使得机械设备高频扰力导致的结构振动问题越来越突出;为了减轻结构的高频受迫振动响应,可以在结构振动响应较大的位置安装高频高阻尼比的钢板夹层阻尼悬臂梁式调谐质量阻尼器(tuned mass damper,TMD)。由于TMD的弹性元件与阻尼元件相互耦合,因此根据TMD的目标参数进行TMD尺寸设计时需要反复迭代;为了提高设计效率,提出了解耦的TMD两阶段快速设计方法。首先根据模态应变能法推导得到了夹层阻尼悬臂梁的一阶模态阻尼比公式,根据截面弯矩转角关系推导了夹层阻尼悬臂梁的复合截面抗弯刚度公式,进而得到了夹层阻尼悬臂梁结构的动力特性计算公式,公式表明夹层阻尼悬臂梁的动力特性相互耦合。而后,利用推导的公式研究了几何参数对钢板夹层阻尼悬臂梁的一阶频率和模态阻尼比的影响,结果表明结构各部分尺寸的等比例缩放不影响构件的阻尼比,得出了阻尼比与频率可解耦的规律。据此规律提出了高频TMD的两阶段快速设计方法及流程:先根据TMD的目标阻尼比确定结构各部分之间的尺寸关系,然后根据目标频率确定构件尺寸。最后,运用所提出的方法,给出了微型化高频高阻尼比夹层阻尼悬臂梁集合式TMD的设计示例,并对示例模型进行了有限元分析,有限元计算结果与设计目标的偏差小于2%,进一步验证了所提方法的有效性。展开更多
Kagome based high authority shape morphing structure is a kind of truss-cored sandwich metal plate with a planar Kagome truss as one of its face plane. The planar Kagome truss can achieve arbitrary in-plane nodal disp...Kagome based high authority shape morphing structure is a kind of truss-cored sandwich metal plate with a planar Kagome truss as one of its face plane. The planar Kagome truss can achieve arbitrary in-plane nodal displacements with minimal internal resistance when its rods are deformed. Moreover, the in-plane deflection of the planar Kagome truss may induce the lateral deflection of the whole sandwich plate. In this paper, the feasibility to enhance the damping of the truss-cored sandwich plate through the replacement of a very small portion of rods in the planar Kagome truss by cylindrical viscoelastic dampers is exploited. The Biot model is chosen to simulate the behavior of the viscoelastic material in the dampers, and the fraction of axial modal strain energy of the rods in the planar Kagome truss is adopted as the index to decide the positions of the dampers. Through complex modal analysis and time-domain simulation, it is shown that the passive vibration control approach is very effective for the vibration reduction of this kind of truss-cored sandwich plates.展开更多
文摘在小变形线弹性理论的基础上,构造了阻尼夹层板单元。对三层板均采用M ind lin板单元,以各层的中面为坐标平面建立局部坐标系来建立有限元模型,芯层材料的粘弹性采用常复数模型。对其动态特性进行了有限元分析,采用求解复特征值的方法求得了其频率和损耗因子。在此基础上进行了详细的数值计算与分析,讨论了粘弹性阻尼层的厚度、模量、损耗因子对结构动力特性的影响,对结构的阻尼机理有了进一步理解,得到了一些有工程应用价值的结论。最后分别对单一铝板、自由阻尼层板和约束阻尼层板进行了模态实验,验证了理论计算的正确性。
文摘随着工业化的发展,建筑结构逐渐轻量化,机械设备逐渐重型化、高效化,这使得机械设备高频扰力导致的结构振动问题越来越突出;为了减轻结构的高频受迫振动响应,可以在结构振动响应较大的位置安装高频高阻尼比的钢板夹层阻尼悬臂梁式调谐质量阻尼器(tuned mass damper,TMD)。由于TMD的弹性元件与阻尼元件相互耦合,因此根据TMD的目标参数进行TMD尺寸设计时需要反复迭代;为了提高设计效率,提出了解耦的TMD两阶段快速设计方法。首先根据模态应变能法推导得到了夹层阻尼悬臂梁的一阶模态阻尼比公式,根据截面弯矩转角关系推导了夹层阻尼悬臂梁的复合截面抗弯刚度公式,进而得到了夹层阻尼悬臂梁结构的动力特性计算公式,公式表明夹层阻尼悬臂梁的动力特性相互耦合。而后,利用推导的公式研究了几何参数对钢板夹层阻尼悬臂梁的一阶频率和模态阻尼比的影响,结果表明结构各部分尺寸的等比例缩放不影响构件的阻尼比,得出了阻尼比与频率可解耦的规律。据此规律提出了高频TMD的两阶段快速设计方法及流程:先根据TMD的目标阻尼比确定结构各部分之间的尺寸关系,然后根据目标频率确定构件尺寸。最后,运用所提出的方法,给出了微型化高频高阻尼比夹层阻尼悬臂梁集合式TMD的设计示例,并对示例模型进行了有限元分析,有限元计算结果与设计目标的偏差小于2%,进一步验证了所提方法的有效性。
基金supported by the National Basic Research Program of China ("973" Project) (Grant No. 2006CB601206)
文摘Kagome based high authority shape morphing structure is a kind of truss-cored sandwich metal plate with a planar Kagome truss as one of its face plane. The planar Kagome truss can achieve arbitrary in-plane nodal displacements with minimal internal resistance when its rods are deformed. Moreover, the in-plane deflection of the planar Kagome truss may induce the lateral deflection of the whole sandwich plate. In this paper, the feasibility to enhance the damping of the truss-cored sandwich plate through the replacement of a very small portion of rods in the planar Kagome truss by cylindrical viscoelastic dampers is exploited. The Biot model is chosen to simulate the behavior of the viscoelastic material in the dampers, and the fraction of axial modal strain energy of the rods in the planar Kagome truss is adopted as the index to decide the positions of the dampers. Through complex modal analysis and time-domain simulation, it is shown that the passive vibration control approach is very effective for the vibration reduction of this kind of truss-cored sandwich plates.
