VIRALL复合板的振动阻尼特性

采用悬臂梁横向弯曲自由振动方法，研究了单向增强ＶＩＲＡＬＬ复合板及相应的单一铝合金板的振动阻尼性能。结果表明，前者的振动衰减系数高于后者，还发现ＶＩＲＡＬＬ复合板的阻尼性能受其纤维取向影响。     

磁流变振动工作台优化设计

本文设计和开发磁流变振动工作台。它包括可控振源、信号采集、动力学分析、磁流变阻尼振动控制等。介绍其工作原理、结构特点，并探讨阻尼孔间隙、活塞直径等结构设计参数对机构性能的影响，提出多目标规划的磁流变阻尼器优化设计模型，综合考虑阻尼力和结构的动态品质，规定权重和子目标的追求值，设计出满足不同要求的、性能优良的阻尼器和振动控制系统。     

焊接应用——焊接结构与设计——结构阻尼变化与振动时效效果的评定

振动时效过程幅频曲线变化的理论基础是振动阻尼的变化，分析了结构阻尼（滞后阻尼）在振动时效过程中的作用，应用动态机械分析仪对焊接小试样应变阻尼进行了实测，指出了结构阻尼在振动过程中有升高后缓降的变化，这是导致幅频曲线复杂变化的原因之一。通过对比了振动时效的机械行业标准JBT5926-1991标准和JBT103752002标准中关于振动时效效果的幅频曲线评定方法的异同，通过对HT-7U核聚变试验装置的振动时效幅频曲线分析，指出对焊接结构的振动时效采用JBT103752002技术标准进行效果评定更具实用性。     

锻造机器人金属橡胶关节阻尼设计及振动抑制

为了抑制锻造车间内锻压机等设备给锻造机器人造成的残余振动,开展机器人的金属橡胶关节阻尼设计及其振动抑制性能分析。基于冲击响应理论获得锻造环境中锻压机冲击的半正弦脉冲激励;根据SPONE的线性弹簧假设及关节刚-柔耦合特性,在COMSOL 平台上建立了六自由度锻造机器人的几何模型;对锻造机器人关节中金属橡胶垫片的减振阻尼特性进行分析;最后在COMSOL平台上完成了7种状态下锻造机器人的振动响应试验,并对丝径分别为0.10、0.20、0.25、0.30 mm的4种金属橡胶关节阻尼进行了残余振动抑制测试。测试结果表明：当关节4~关节6都呈0°时,极限状态4下无阻尼机器人末端最大位移为0.19 mm;而4种金属橡胶关节阻尼的机器人末端位移分别降低了85.8%、99.5%、100%和100%,且金属丝径为0.25 mm时抑振效果最好,从而验证了在锻造机器人中增加金属橡胶关节阻尼抑制残余振动的有效性。     

振动时效判据分析

在分析了振动时效机更换 基础上,提出用残余应力消除多少的方法来评定振动时效效果存在不足之处,认为振动时效必定会导致工件阻尼的减少,以此为线索,通过建立振动时效力学模型,用振动学理论推导了阻尼减少所体现的振动动态参数的变化规律,由此解释了用振动动态参数（振幅、固有直流终究宽等）变化来判定振动时效效果的理论依据,并以机床床身振动时效为例对此法进行了验证。     

基于闭环PID控制的磁流变液阻尼减振器减振性能测试

针对某结构的振动特性及磁流变液阻尼减振器的工作方式,设计了一套用于检测其磁流变液阻尼器减振效果的测试系统,根据传感器检测到结构的振动信号输入到计算机和磁流变液阻尼减振器的控制器,通过PID方法控制伺服电机的回转速度和方向及外界磁场强度,从而改变输出控制力和阻尼的大小.试验表明,采用该方法,达到了降低结构响应振幅值的目的,提高磁流变液阻尼器的减振控制性能.     

冷轧机轧制过程中轧辊垂振的研究

以冷轧机系统的垂振为研究对象,结合近年来冷轧机垂振问题的研究成果,得出冷轧机垂直振动的振源在辊缝.冷轧机在高速轧制时,辊缝润滑状态发生变化导致辊缝阻尼改变,从而引起轧机的垂直振动.建立了冷轧机简化模型,并对冷轧机轧制过程进行仿真,分析了辊缝阻尼与轧机垂直振动之间的关系,得出辊缝阻尼变小导致轧机的垂直振动.通过增大辊缝间的摩擦系数和增设阻尼设备的方法维持合适的辊缝阻尼,可消除轧辊的垂直振动,保证轧机平稳运转.     

累积叠轧ZK60/Al复合板材的微观组织及性能研究

通过累积叠轧工艺制备出Al/ZK60/Al复合板,采用SEM、TEM、万能拉伸试验机、动态热机械分析仪研究了变形道次对ZK60/Al复合板材的微观组织及性能的影响。结果表明,不同变形道次复合板界面结合良好,无明显颈缩,断裂现象。随道次增加,ZK60/Al复合板的抗拉强度呈现先上升后下降的趋势,ARB-1道次时复合板的抗拉强度为216 MPa,伸长率达到最大值为2.6%。ZK60/Al多层复合板的温度-阻尼谱存在两个明显的内耗峰,即150℃左右的P_1弛豫型阻尼峰,300℃左右的P_2再结晶阻尼峰;ZK60/Al多层复合板材的应变-阻尼谱呈现典型的位错阻尼机理,应变阻尼可以用G-L理论分析。     

刨床工作台振动特性分析

由于受到各种激励,刨床工作台运动过程中将发生振动,从而影响加工精度。为了有效控制工作台的振动,提高加工精度,有必要对工作台的振动特性进行分析。为此,以一自由度弹簧-质量-阻尼系统为工作台振动力学模型,在时域范围内分析受到谐波激励的刨床工作台的振动特性。结果表明:运动初期,工作台的振动由自由振动、自由伴随振动及稳态振动三部分组成;工作台运动后期,以稳态振动为主;工作台的振幅与其运动速度及阻尼有关,为了有效控制工作台的振动,必须合理控制阻尼值,并且合理选择工作台的运动速度。     

冷带轧机振动及干摩擦阻尼减振的仿真研究

考虑轧机振动过程中辊缝的非线性，本文建立了以轧制理论公式为基础，计算简便、快速的动态轧制力计算模型，结合轧机垂直振动简化力学模型，对高速冷带轧机振动及干摩擦阻尼减振等进行了数值仿真研究。     

3种材料在柔性机械臂振动抑制中的特性对比

在所设计的柔性机械臂的基础上,利用SolidWorks Simulation对合金钢、铝合金、碳纤维增强环氧树脂基复合材料3种结构材料的机械臂进行线性动态分析,分别从谐波分析和瞬态振动分析两个方面对机械臂进行仿真。结果表明,碳纤维增强环氧树脂基复合材料对机械臂具有明显的减振作用,其振动衰减速度及振动衰减效果要优于传统合金材料,为机械臂的设计及振动抑制提供了参考。     

Improvement of viscoelastic damping in nickel aluminum bronze by indium-tin

Reduction of the vibration noise from submarine propellers is of interest in naval operations. Such an objective can be achieved via the use of materials with the ability to dissipate energy of vibration by means of heat, i.e. high damping materials. An additional problem is that the extreme hydrostatic pressure environment of a submarine requires the chosen material to exhibit considerably high stiffness. Most materials demonstrate a compromise between the two properties, i.e. stiffness and damping. This paper aims to discuss research into high stiffness and high damping materials conducted using a dynamic mechanical analyzer (DMA) under variations of testing temperature, frequency, and strain amplitude. Alloys of nickel aluminum bronze and indium tin are the subjects of this study. Defect damping represents a large portion of the overall damping properties of the nickel aluminum bronze while increasing indium content is shown to boost the damping properties of the indium tin alloy. The study then continues with the development of a new material that combines both indium alloying and defects introduction into the nickel aluminum bronze alloy. The new alloy is observed to have high damping, as measured in its high tan δ, with minimum reduction of the stiffness |E*|.     

The mechanical behavior of GLARE laminates for aircraft structures

GLARE (glass-reinforced aluminum laminate) is a new class of fiber metal laminates for advanced aerospace structural applications. It consists of thin aluminum sheets bonded together with unidirectional or biaxially reinforced adhesive prepreg of high-strength glass fibers. GLARE laminates offer a unique combination of properties such as outstanding fatigue resistance, high specific static properties, excellent impact resistance, good residual and blunt notch strength, flame resistance and corrosion properties, and ease of manufacture and repair. GLARE laminates can be tailored to suit a wide variety of applications by varying the fiber/resin system, the alloy type and thickness, stacking sequence, fiber orientation, surface pretreatment technique, etc. This article presents a comprehensive overview of the mechanical properties of various GLARE laminates under different loading conditions. For more information, contact J.-M. Yang, University of California, Department of Materials Science and Engineering, 6532 Boelter Hall, Los Angles, CA 90024; (310) 825-2758; fax (310) 206-7353; e-mail jyang@seas.ucla.edu.     

体育器材用TiAl3/AlSi11Cu3铝合金组织和力学性能优化

利用超声振动法制备体育器材用AlSi11Cu3铝合金,通过添加K₂TiF₆粉末原位反应生成TiAl₃增强相的方法对铝合金进行颗粒增强,研究了超声功率和颗粒增强对AlSi11Cu3铝合金微观组织和力学性能的影响。试验结果表明,最佳的超声功率为1 kW,超声振动和TiAl₃增强相的引入能明显细化铝合金组织,大幅提升铝合金的拉伸性能和硬度,抗拉强度、伸长率和硬度分别提升了33.9%、23.6%和38.8%,断裂特征由准解理断裂逐渐向韧性断裂转变。     

振动环境中锌铝/珍珠岩多孔复合材料的阻尼性能研究

讨论了振动环境中锌铝/珍珠岩多孔复合材料的阻尼性能.实验利用真空浸渗法制备了锌铝合金/珍珠岩复合材料,并利用DTM-Ⅱ-X型动态弹性模量阻尼内耗分析仪在共振条件下测试其杨氏模量及材料阻尼内耗值,分析了其阻尼机理.试验结果表明锌铝合金/珍珠岩金属基复合材料的阻尼性能要大大优于基体金属.     

层压板和蜂窝结构粘接缺陷的超声C扫描检测

介绍了用某超声C扫描检测设备检测碳纤维环氧层压板、碳环氧板纸蜂窝粘接结构、铝板铝蜂窝粘接结构三种材料粘接缺陷的试验结果。试验用的试块带有4,10,16mm三种尺寸的人工缺陷,用于模拟各种脱粘缺陷。采用喷水探头透射法,用5MHz超声检测层压板,用1MHz超声检测蜂窝结构,都得到了人工缺陷的清晰准确的C扫描图。对于厚度为135mm的纸蜂窝结构,因超声衰减太大,尚不能检测。     

改善铸造法制造MMCp中铝基体与增强颗粒间润湿性的方法

介绍用铸造法制造颗粒增强金属基复合材料时,熔融铝合金与增强颗粒之间润湿性的改善方法.常用的改善润湿性的方法有:添加合金元素、对增强颗粒表面进行预处理、在颗粒表面涂敷一层金属层.另外,机械振动、超声振动以及适当延长混合时间也可以改善增强颗粒与金属基之间的润湿性.     

降低强夯振动对建构筑物影响的实践与探索

通过某铝厂强夯地基处理的工程实践,对回填碎块石土进行强夯振动时所产生的地面振动进行了现场监测,分析强夯振动的特征及振动速度衰减规律,评价隔震沟的减震作用及效果,根据设计的强夯参数进行强夯施工,使强夯振动对周围建构筑物造成的危害大为降低.     

Toughness Enhancement in Roll-Bonded Al6061-15 vol.% SiC Laminates via Controlled Interfacial Delamination

Researchers have examined different approaches to improve damage tolerance of discontinuously reinforced aluminum (DRA). In this study, three-layer DRA laminates containing two exterior layers of Al6061-15 vol.% SiCp and an interlayer of Al1050 were fabricated by hot roll bonding. Interfacial adhesion between the layers was controlled by means of rolling stain. The results of shear test revealed that, the bonding strength of laminates was influenced by number of rolling passes. Considering this effect, the role of interfacial bonding on the toughness of laminates was studied under three-point bending in the crack divider orientation. The quasi-static toughness of the laminates was greater than that of the monolithic DRA. Plastic deformation of the ductile interlayer and interfacial delamination were found as the major sources of energy absorption in this fracture process. It was shown that interfacial adhesion in these laminate does not alter the initiation energy in quasi-static test. Propagation energy under same loading condition, however, illustrated significant sensitivity to the interfacial bonding. The results of the current study reveal that improving the interfacial adhesion by means of rolling strain eliminates the ease of plastic deformation of the ductile interlayer and thus reduces the contribution of this mechanism in quasi-static toughness of the laminate.     

Strength of fiber reinforced metal laminates with a circular hole

The effect of notching on fiber-reinforced metal laminates (FML) is studied 3-2 lay up carbon fiber aluminum laminates specimens containing a circular hole were employed in notch tests. The notch effect for a composite laminate was investigated and compared with carbon/epoxy composites and aluminum sheets. The degradation of notch strength for carbon fiber aluminum laminates was smaller than for carbon/epoxy composites. The point and average stress criteria were used in the notch strength analysis. A finite width correction factor was also used. The strength degradation models involve a single parameter that is a function of the hole size and the characteristic length. These models were compared with experimental data and good agreement was found.