基于修正变分法开孔板和加强板结构的自由振动分析

为研究船舶开孔板和加强板结构的振动特性,用1阶剪切变形板理论描述各向同性板的位移场,并采用修正变分原理和区域分解方法建立板的离散动力学模型.每一块子域板的位移和转角分量通过第一类切比雪夫正交多项式展开.针对加强板模型,将该方法获得的结果与已经发表的文献和有限元商用软件计算结果进行对比,验证该方法的收敛性和正确性.基于修正变分法探讨多种开孔和加强板模型的自由振动特性,充分说明该数理模型和半解析方法是一种适合处理复杂板结构问题的数值工具.     

结合灵敏度分析的圆锥壳-折板结构动力学研究

圆锥壳-折板结构在航空舱体装备结构中十分常见,作为航空装备重大核心精密科学仪器设备的承载体,舱体结构强度设计问题尤为关键.本文以圆锥壳-折板结构为对象,对其动力学特性展开分析.通过仿真计算,得到圆锥壳-折板结构在随机振动下的响应结果,并且建立材料参数与动力学响应之间的响应面函数.进一步利用Spearman秩相关系数,进行灵敏度分析,筛选出圆锥壳与折板结构中影响舱体结构动强度的主要因素.最后得到各个主要因素对于响应面动力学响应的影响规律曲线.     

利用激光光源实现镍网开孔率的检测

分析了用光通量测量法镍网开孔率的理论依据和现有技术的缺点,采用激光二极管作为光电探头光源,使用四个光电二极管获取开孔率采样值,通过计算机软件校正光电二极管的非线性,采用多重数字滤波技术提高仪器的精度和的稳定性,实现自动测量、自动校准,同时还提供了与上位机通信的Max232接口.     

利用激光光源实现镍网开孔率的检测

分析了用光通量测量法镍网开孔率的理论依据和现有技术的缺点,采用激光二极管作为光电探头光源,使用四个光电二极管获取开孔率采样值,通过计算机软件校正光电二极管的非线性,采用多重数字滤波技术提高仪器的精度和的稳定性,实现自动测量、自动校准,同时还提供了与上位机通信的Max232接口。     

尾气再热器大开孔区域基于ANSYS软件在壳程和夹套压力共同作用下的校核评定

通过有限单元法,对尾气再热器大开孔区域在壳程和夹套压力共同作用下进行应力计算和强度分析。根据计算结果,判定该设备在该处的安全性,也为此类超标准设计的校核评定提供了新的方法和新思路。     

基于超声波原理的开孔参数标定系统研究

针对传统的人工丈量方法标定开孔方位角和倾斜角存在操作程序繁琐、稳钻时间长、精度低等问题,设计了基于超声波原理的钻孔开孔参数标定系统。该系统采用超声波渡越时间检测法测量参考点之间的距离,并由单片机解算出钻杆的方位角,选用微机械三轴加速度计测量倾斜角,实现了全自动化的实时跟踪测量及智能化的钻机姿态调整语音指导操作;在误差允许范围内,可快速标定所需开孔参数。该系统提高了开孔参数标定精度、标定效率及煤矿管理水平,降低了矿工劳动强度和煤矿管理成本。     

基于超声波原理的开孔参数标定系统研究

针对传统的人工丈量方法标定开孔方位角和倾斜角存在操作程序繁琐、稳钻时间长、精度低等问题,设计了基于超声波原理的钻孔开孔参数标定系统。该系统采用超声波渡越时间检测法测量参考点之间的距离,并由单片机解算出钻杆的方位角,选用微机械三轴加速度计测量倾斜角,实现了全自动化的实时跟踪测量及智能化的钻机姿态调整语音指导操作;在误差允许范围内,可快速标定所需开孔参数。该系统提高了开孔参数标定精度、标定效率及煤矿管理水平,降低了矿工劳动强度和煤矿管理成本。     

圆锥扫描单脉冲雷达测角特性分析

单脉冲雷达因其测角精度高,抗干扰能力强,使其得到了广泛的应用.本文分析了隐蔽圆锥法扫描原理,并对实际中应用比较广泛的比幅单脉冲雷达进行仿真.     

对接圆柱壳结构模态特性分析

对接圆柱壳结构在航空航天、船舶、土木和机械等工程领域得到广泛应用,对其模态特性的分析是研究其动力学特性的重要方向.本文简要介绍了模态分析技术和最小二乘复频域法(PolyMAX)的基本原理,并对对接圆柱壳结构进行了计算模态分析和实验模态分析.实验模态分析过程中,针对自由边界的实验实现、分析结果的正确性进行了讨论,并将实验结果与计算模态分析结果进行对比,对比结果表明：对接圆柱壳结构具有圆柱壳结构一般振动特性的同时,由于对接形式的存在出现了以法兰面为分界的非对称振动.     

煤矿井下开孔定向仪寻北系统误差分析及补偿

针对现有钻机开孔定位装备在测量精度、成本及操作性上不能满足实际需求的问题,设计了一种将基于单轴光纤陀螺的寻北系统与基于微惯性测量单元的跟踪系统相结合的新型钻孔开孔定向仪。以四位置寻北方法为例,介绍了寻北系统的基本原理,并从光纤陀螺的输出误差、安装误差、倾斜角误差、转位误差、地球物理量误差等方面介绍了寻北系统的各种误差及来源。针对安装误差和倾斜角误差,建立了非线性加速度误差补偿模型;针对光纤陀螺的随机漂移误差,采用卡尔曼滤波方法进行修正。实验结果表明,减小倾斜角、光纤陀螺随机漂移误差、转动机构转位误差、安装误差均可有效提高开孔定向仪寻北精度,满足煤矿井下钻探需求。     

带孔等厚薄壳荷重传感器弹性元件的形状优化

建立带孔等厚薄壳荷重传感器弹性元件的优化参数模型、有限单元计算模型及优化数学模型,确定电阻应变计的粘贴位置,用结构分析软件ANSYS5.7及一阶优化方法优化弹性元件的形状,提高弹性元件在贴片位置的应变响应。     

含初应力复合材料柱壳结构的双稳态特性

为分析初应力对复合材料圆柱壳结构双稳态特性的影响,采用经典板壳理论建立复合材料圆柱壳力学模型,基于层合结构本构关系推导用双参数表达的系统应变能公式;根据最小势能原理得到双稳态产生的条件和稳态时的曲率表达式。利用Abaqus软件构建圆柱壳的有限元模型,通过附加边界弯矩对柱壳稳态跃迁过程进行模拟。理论计算结果与有限元结果的对比验证理论模型的正确性。分析结果表明：当初应力满足一定条件时,复合材料柱壳结构在其变形过程中有2个稳定平衡位置,并且在稳定平衡位置结构都不产生扭转变形;2个稳定平衡位置的曲率方向可以相同或相反,这与无初应力时反对称复合材料柱壳双稳态曲率方向只能相同的情况有区别。     

Precise Design and Stress Analysis of Straight Conical Gear

1 Introduction Straight conical gears are widely used in power transmission between perpendicular shafts. In the last few decades, there has been a growing interest in conical involute gears. Apart from being frequently used in anti-backlash schemes, they are, according to Mitome, also used as reduction gears[1], miter gears, trimming gears and differential gears. The conical involute gear, which is also called beveloid gear by some authors, is an involute gear with tapered tooth thickness, t…     

Generation of orbital angular momentum vortex beams with cylindrical and conical conformal array antennas

In this article, cylindrical and conical conformal arrays are presented to flexibly launch the OAM vortex beams. First, we analyze the characteristics of OAM beams generated by planar annular arrays with different radii. Then characteristics of vortex waves generated by cylindrical and conical arrays with different curvatures are analyzed. Finally, prototypes of cylindrical and conical arrays are fabricated and measured. Experimental results imply that OAM vortex beams can be effectively generated by cylindrical and conical conformal phased arrays, which may provide a reference for electromagnetic vortex communication on the conformal carrier in the future.     

地铁车轮振动声辐射特性和车轮降噪

为降低地铁车轮振动噪声,建立车轮三维有限元模型实体网格,利用有限元法计算车轮的固有频率和模态振型;将径向单位力激励下的车轮表面振动速度作为边界条件,采用直接边界元法分析车轮振动声辐射特性;利用阻尼措施降低车轮辐射噪声.结果表明：轮辐和踏面是产生高频噪声的主要部位,在3 731.3 Hz的声功率级最高为69.2 dB(A),此频率下轮辐对总声压贡献最大;采用阻尼措施后声功率级最高值下降4.7 dB(A).数值仿真结果可以为低噪声车轮的研究提供参考.     

Evaluation of head and neck motion with the hemispherical shell method

This paper presents the development of a simple method for the measurement of head motion for patients with neck injuries. The patients with neck injuries pose unique problems and the existing methods mostly using goniometers are not suitable for their evaluation in a clinical setting. The presented method involves the use of a hemispherical shell mounted with the help of a frame over the head of the patient. Two light sources are mounted on the patient's head and the readings are taken from circular scales marked on the outer shell surface. Equations are developed to convert these readings into the ranges of head motion. The results obtained with the presented method for normal adults are compared with the results from the previous methods. The data for the patients with neck injuries will be useful in the individualized design of instruments such as headstick operated keyboards, computers or keyboard-like devices.

Relevance to industry

For the industrial employment of patients with neck injuries, an accurate evaluation of their abilities is important, particularly when job modifications are needed so that they can be viable employees in industry. The head motion obtained with this new method for patients with neck injuries will be useful in the individualized design of instruments such as headstick operated keyboards, computer interfaces, communication devices or keyboard-like devices. The proposed method is simple, inexpensive, reasonably accurate and can be used in a clinical setting.     

带锥敏感薄膜形变特性有限元仿真

在一种新的基于真空二极管原理的场发射压力传感器中 ,阴极发射尖锥体和敏感薄膜制备于同一硅片上 ,从而简化了传感器的封装工艺 ,但因此可能导致传感器灵敏度的减小。利用有限元仿真技术 ,计算了在外部压力作用下 ,几何形状比较复杂的带尖锥体敏感薄膜的横向挠度形变特性。计算结果表明 ,与不带尖锥体的敏感薄膜相比较 ,带尖锥体敏感薄膜在额定外部静压力作用下的最大横向挠度的减小量小于 0 .4% ,因此对传感器灵敏度的影响可以忽略不计     

Free vibration analysis of functionally graded conical, cylindrical shell and annular plate structures with a four-parameter power-law distribution

Based on the First-order Shear Deformation Theory (FSDT) this paper focuses on the dynamic behavior of moderately thick functionally graded conical, cylindrical shells and annular plates. The last two structures are obtained as special cases of the conical shell formulation. The treatment is developed within the theory of linear elasticity, when materials are assumed to be isotropic and inhomogeneous through the thickness direction. The two-constituent functionally graded shell consists of ceramic and metal. These constituents are graded through the thickness, from one surface of the shell to the other. A generalization of the power-law distribution presented in literature is proposed. Two different four-parameter power-law distributions are considered for the ceramic volume fraction. Some material profiles through the functionally graded shell thickness are illustrated by varying the four parameters of power-law distributions. For the first power-law distribution, the bottom surface of the structure is ceramic rich, whereas the top surface can be metal rich, ceramic rich or made of a mixture of the two constituents and on the contrary for the second one. Symmetric and asymmetric volume fraction profiles are presented in this paper. The homogeneous isotropic material can be inferred as a special case of functionally graded materials (FGM). The governing equations of motion are expressed as functions of five kinematic parameters, by using the constitutive and kinematic relationships. The solution is given in terms of generalized displacement components of the points lying on the middle surface of the shell. The discretization of the system equations by means of the Generalized Differential Quadrature (GDQ) method leads to a standard linear eigenvalue problem, where two independent variables are involved without using the Fourier modal expansion methodology. Numerical results concerning six types of shell structures illustrate the influence of the power-law exponent, of the power-law distribution and of the choice of the four parameters on the mechanical behaviour of shell structures considered.     

某航天器装载结构特征与力学特性分析

针对某新型航天器携带有效载荷的基本结构形式——装载结构,研究其结构构型对其力学性能的影响.建立该装载结构的有限元模型,量化分析其内部支撑形式、支点数和关键结构件截面性能等结构特征参数对其强度、基频和质量等结构力学特性与性能的影响.结果表明,内部支撑形式对装载结构动力学特性贡献明显;合理的内部支撑形式可以用较小的质量代价实现基频要求,并可以减少支点数量,方便在轨安装操作.