国产温敏Z—元件的特性与分析

本文介绍一种高性能新型国产敏感元件——温敏Ｚ－元件的结构、符号、命名方法和伏安特性,对其温敏特性予以分析。     

TiO2—K2O—LiZnVO4陶瓷薄膜的制备及其湿敏性能研究

采用溶胶凝胶法制备了ＴｉＯ２－Ｋ２Ｏ－ＬｉＺｎＶＯ４陶瓷薄膜湿敏元件,研究了薄膜的结构和元件的感湿性能。薄膜主要由金红石型ＴｉＯ２构成,化学组成为Ｔｉ：Ｋ：Ｌｉ：Ｚｎ：Ｖ：Ｏ＝１：０．０４：０．１：０．１：０．１：２．４２（原子摩尔比）。工作频率为４０Ｈｚ时,湿敏元件在全湿度范围内具有良好的阻抗一湿度特性及电容－湿度特性,感湿特性曲线线性良好。元件还具有灵敏度高,滞后小,响应快,长期稳定性好等优点     

Cu基形状记忆合金螺旋弹簧热机性能研究

论述了形状记忆合金（SMA）弹簧驱动元件的应力,应变,温度和相变之间的测试关系并进行了系统的测试,结果表明,SMA弹簧元件在三种基本使用状态下的应力－应变－温度关系呈非线性,设计中不能直接应用虎克定律,测试结果为进一步揭示SMA驱动特性及SMA驱动元件设计提供了参考依据。     

一种基于电磁型微马达的微摩擦测试装置

随着ＭＥＭＳ技术的发展,人们迫切需要对微观世界的摩擦现象进行研究测试,以求发现宏观与微观世界中摩擦现象的联系和区别,但由于测试条件的限制,现在还很难对微观世界进行直接测试。文中提出了一种全新的微小摩擦测试方法－－间接测量法,利用了微型马代同时作为驱动元件和测试元件,通过分析微马达在施加力前后其运动特性的改变,间接地计算出微小摩擦力的大小。文中对测试机理和系统实现做了详细介绍。     

新型密封元件的结构设计与应用

论述了密封元件的特性要求，分析了工程陶瓷材料的为密封元件的优良特性，设计出了两种新型密封元件结构，阐述了其工作原理及特点，并将其应用于工业控制阀中。     

一种温度调节器及其感温元件的研究

介绍一种双感温元件驱动工作方式的温度调节器,其阀芯升程是两只感温元件行程之和,可进一步增大调节器开度,扩充可调节流量。经理论分析,得出感温元件行程、推动力、内压力的简易特性方程,其变化主要受感温蜡体膨张率等因素的影响,呈非线性变化。通过试验方式对温度调节器的分流特性及双感温元件特性进行研究,结果表明:分流场合下,调节器的分流特性呈两段特性,每段近似线性的比例变化;双感温元件驱动时,感温元件的特性要求可近似参照单感温元件驱动时特性要求。     

WO3对O3敏感特性研究

】实验发现ＷＯ３半导体材料对Ｏ３有好的敏感特性,而且元件的烧结温度和工作温度对其敏感特性有大的影响。在对这些参数优化的基础上,研制出了具有较好特性的Ｏ３气敏元件。测定了元件灵敏度与Ｏ３浓度的关系,初步讨论了元件对Ｏ３气体敏感的机制。     

摩擦片表面沟槽对离合器动态特性影响的研究

本文在研制成功的“离合器摩擦元件动态性能试验台”（专利号：ZL93225298．2）上,按国家标准GB／T15141－94《湿式离合器摩擦元件试验方法》对不同表面沟槽的铜基粉末冶金摩擦片进行了试验和分析研究,得到了七中典型摩擦片表面沟槽的摩擦特性曲线以及动态特性的影响,获得的研究结果可供离合器设计时参考,并为进一步深入研究打下了基础。     

用疲劳寿命计实现的寿命预测方法

疲劳寿命计是电阻－疲劳响应记忆元件，其电阻值随疲劳而增加，载荷卸除后电阻变化值保留。本文介绍所研制疲劳寿命计特性曲线与材料疲劳曲线的拟合方法，设计和标定了应变倍增器。应变倍增器可使疲劳寿命计电阻变化特性曲线的多数材料的疲劳曲线更好拟合。根据疲劳寿命电阻变化值可以预测年的疲劳寿命。     

压电弯曲元件宽度对其特性影响的研究

研制了一种新型的压电弯曲元件,元件为三层结构,上下两层为压电陶瓷材料PZT-5H,中间弹性层为铍青铜.利用激光测试仪LC-2400A及LV-1610对压电弯曲元件的输出位移、位移滞环、蠕变量及基频等特性进行测量.对压电弯曲元件的宽度尺寸与其静、动态特性之间的关系进行分析,得出压电弯曲元件的宽度参数对其静、动态特性影响较...     

纳米磁流体密封结构的设计和制造

论述了磁流体及其密封的原理和特点,介绍了密封结构的形式、密封元件的组成、密封结构设计的分类和步骤,研究了密封结构参数对密封能力的影响及各参数的选取原则,针对一具体情况,选择一源二极密封部件进行研究,具体设计并制作出一个30级密封结构元件,讨论了加工和安装过程中应注意的问题。     

Vibration—Analysis of circular-arc aerofoil shaped plates

Circular-arc aerofoil flat plates are analysed for their vibrational characteristics using the finite element approach. The effect of variation in the lune angles of the aerofoil plates, on natural frequencies and mode shapes is investigated. Two types of plate bending finite elements are used in the investigation; one is the conventional nine degree of freedom triangular element and the other is a modified triangular element with one edge curved. The later element has been specially developed and used near the curved boundaries of the plate, whereas the former straight edged element is used in the interior. The results of the finite element analysis are verified through experimental investigations.     

Vibration analysis of composite pipes using the finite element method with B-spline wavelets

A finite element formulation using the B-spline wavelets on the interval is developed for modeling the free vibrations of composite pipes. The composite FRP pipe element is treated as a beam element. The finite pipe element is constructed in the wavelet space and then transformed to the physical space. Detailed expressions of the mass and stiffness matrices are derived for the composite pipe using the B-spline scaling and wavelet functions. Both Euler-Bernoulli and Timoshenko beam theories are considered. The generalized eigenvalue problem is formulated and solved to obtain the modal characteristics of the composite pipe. The developed wavelet-based finite element discretization scheme utilizes significantly less elements compared to the conventional finite element method for modeling composite pipes. Numerical solutions are obtained to demonstrate the accuracy of the developed element, which is verified by comparisons with some available results in the literature.     

基于分段连续ANCF缆索单元的输电线缆动力学建模与仿真

在绝对节点坐标缆索单元和Bézier/B样条几何体关系的基础上,构造了分段连续的ANCF缆索单元。单元形函数为分段连续函数,给出了其递推形式的定义式。单元在内节点处的连续性取决于单元节点坐标的选取以及形函数的定义方式。给出了单元弹性力及其对节点坐标雅可比矩阵的定义。进而采用该单元,建立了输电线缆架设过程中断线工况的动力学分析模型。可以实现用一个单元表示整条电缆线,从而在动力学仿真程序中避免了反复进行的单元到系统的集成及系统到单元的离散过程。用静力学分析计算得到输电线缆在重力、张紧力等外力共同作用下达到平衡时的节点坐标值,将其作为初值输入给动力学仿真程序,以模拟张紧力对输电线缆动力学行为的影响。建立了静、动力学仿真算例验证了单元的准确性,并给出了输电线缆的动力学仿真结果。     

滚动轴承疲劳故障在线诊断的研究

通过对滚动轴承振动信号的在线监测提取出对疲劳故障敏感的参数：峭度、功率谱故障频带能量值、小波包故障频带能量值．选择足够的具有代表性的样本数据训练神经网络,用训练好的神经网络进行在线诊断,可以得出轴承发生疲劳故障的程度,再经过共振解调法诊断出轴承具体损伤的元件,实验表明本方法对滚动轴承的疲劳故障能正确诊断。该监测和诊断方法对其他设备的监测和诊断也有重要的意义。     

Y形和Y环形单元特性的实验对比研究

采用镀膜和光刻技术设计并制备出了2种衬底厚度不同的Y孔单元和Y环孔单元的FSS,在0°和45°入射角下分不同的极化波进行了测试,经对比研究发现,在大角度入射下Y环单元FSS比Y孔单元FSS有更为稳定的中心频率,更窄的带宽;Y环单元FSS对垂直和水平极化波的适应性更强,滤波特性较Y孔单元FSS更明显;介质厚度的变化对Y孔中心频率、带宽的影响要比Y环单元FSS的大得多。所以,从中心频率、带宽随介质衬底厚度、入射角度、不同极化方式的变化情况看,Y环单元比Y孔有更稳定的性能。     

Formulation method for solid-to-beam transition finite elements

Various transition elements are used in general for the effective finite element analysis of complicated mechanical structures. In this paper, a solid-to-beam transition finite element, which can be used for connecting a C¹-continuity beam element to a continuum solid element, is proposed. The shape functions of the transition finite element are derived to meet the compatibility condition, and a transition element equation is formulated by the conventional finite element procedure. In order to show the effectiveness and convergence characteristics of the proposed transition element, numerical tests are performed for various examples. As a result of this study, following conclusions are obtained. (l) The proposed transition element, which meets the compatibility of the primary variables, exhibits excellent accuracy. (2) In case of using the proposed transition element, the number of nodes in the finite element model may be considerably reduced and the model construction becomes more convenient. (3) This formulation method can be applied to the usage of higher order elements.     

Microscopic approach of powder compaction using finite element method

An approach for simulating microscopic densification behaviour of powder particles in compaction using a finite element method is proposed. In this method, the contacts between powder particles during the compaction are detected, and plastic deformation of the particles is calculated by the finite element method for a porous metal. The finite element mesh is generated by connecting the centres of the particles in contact. It is assumed that the finite elements are porous metals having an average relative density calculated from the volumes of the powder and pore inside the element. The elements are classified into the triangular and quadrilateral ones used in the conventional finite element methods and a linear one for the simple compression. The accuracy of the stiffness for plastic deformation of the particles is improved by applying the finite element method. The calculated plastic deformation of powder particles in plane-strain compaction is compared with that for a model experiment using aluminium rods.     

具有凹坑损伤的海洋平台桩腿有限元分析

采用有限元分析方法，将具有凹坑损伤的构件分割为三个子单元，分别对各子单元建立单元刚度矩阵，然后使用静凝聚法建立受损构件的等效梁和管单元刚度矩阵的计算方法。为检验方法的正确性，使用该方法对几种损伤构件进行强度计算，并与有限元细化网格计算结果和试验结果进行比较，结果表明，三种结果符合很好。最后，将等效单元计算程序接入Super SAP程序，对受损后的平台整体结构进行应力计算和强度分析。     

一种分析旋转梁振动的梁柱有限元

针对旋转柔性梁的弯曲振动问题,提出了一种高精度的有限元——梁柱元。根据旋转梁弯曲时与梁柱相同的受力特点,推导了梁柱元弯曲变形的形状函数,采用传递矩阵方法导出了单元的刚度矩阵及相应的一致质量阵。证明了梁柱元刚度矩阵中各元素的泰勒展开式前两项正好是采用常规弯曲梁元形状函数得到的弹性刚度矩阵和几何刚度矩阵对应的元素的和,因而采用梁柱元分析旋转梁元弯曲振动问题具有很好的精度。对铰支和固支旋转梁振动分析的数值算例也证明了这个结论。