基于端面振动测量的机械密封摩擦学行为试验研究

针对接触式机械密封在运行过程中端面磨损引起性能退化缺乏有效的状态监测方法的问题，提出了用端面振动加速度测量机械密封摩擦学行为的方法.搭建了机械密封试验台，开展了机械密封摩擦学行为测试试验，采集了密封端面振动信号，提取了端面振动特征参数，探究了端面振动敏感特征参数随机械密封摩擦学状态的演变规律，基于试验数据构建了机械密封性能退化评价准则.结果表明：利用端面振动的监测方式可以实现机械密封的摩擦学状态监测；端面振动敏感特征参数模糊熵、均值和排列熵对摩擦学状态敏感；在密封介质压力一定的情况下，密封端面振动信号的模糊熵、均值和排列熵幅值随着机械密封转速的升高而升高，随着机械密封端面磨损程度的升高而升高；通过端面振动敏感特征参量可以表征机械密封的摩擦学状态.     

室内模型实验中低强度桩侧应变片粘贴技术与应用

表面粗糙的桩与桩间土共同受力后发生相对位移,在低强度桩侧面有效粘贴应变片以测试轴力传递规律是一个难点.在组合群桩复合地基室内模型试验中,本文结合传统内贴法和外贴法两种贴片方式的优点,提出并采用凹槽法在低强度实心模型桩外侧面贴片,即在桩侧预留凹槽、用环氧树脂对贴片部位进行表层处理,在贴片后密封凹槽,并给出了典型测试结果.分析认为:凹槽法贴片技术有效可行,可供室内含桩地基基础模型试验借鉴.     

提高载体驱动硅微陀螺灵敏度的方法

载体驱动硅微陀螺是一种利用体微工艺制备的新型电容式振动MEMS陀螺,它安装于旋转飞行器上,利用载体的自旋作为驱动。当载体发生横向转动时,敏感质量受到周期性科氏力的作用,产生振动,从而敏感输入角速度。针对该种MEMS陀螺,首先介绍了陀螺的工作原理和电容式检测结构,然后详细分析了差分电容与敏感质量偏转角之间的关系,最后提出了一种通过调节电容拾取电路的脉冲信号的占空比,来提高陀螺灵敏度的方法。实验测试结果表明,当占空比由50%调整到75%时,相应输出电压峰峰值可由10.7 V提高到13.1 V,提高幅度达22.43%。理论分析和实验结果均表明,该方法可简便有效地提高陀螺灵敏度,具有实际应用价值。     

陶瓷材料SHPB实验的改进垫块法

高强度陶瓷材料SHPB实验中,利用圆柱或圆台形垫块可避免压杆的端面塑性变形,但存在陶瓷试件中轴向的应力不均匀现象,从而影响实验结果的有效性。本文通过数值模拟分析了两种垫块方式引起的试件中轴向应力分布的特点,并以此为基础提出了一种更为合理的垫块方法。利用商业软件LS-DYNA,数值模拟了改进垫块方法的陶瓷材料SHPB实验。结果显示,基本上消除了陶瓷试件中轴向应力不均匀现象。应用一维应力波理论,分析了实验中的波传播过程,得到了对实验数据的修正处理方法,并证明了所提的修正方法是可行有效的。     

SHPB试验中岩石试件的端面不平行修正

为研究短圆柱体岩石试件端面不平行对岩石动力学特性测试结果的影响,采用有限元分析软件LS-DYNA对9种端面不平行度和5种杨氏模量的岩石试件开展SHPB(split Hopkinson pressure bar)试验数值模拟,对岩石选用HJC(Holmquist-Johnson-Cook)本构模型。数值模拟结果表明,当端面不平行度在0.40%以内时,端面不平行对动态应力测试结果的影响可忽略不计;但对动态应变测试结果的影响较大。当杨氏模量一定时,平均应变率测试误差和峰值应变测试误差随端面不平行度增大呈线性增大;当端面不平行度一定时,平均应变率测试误差和峰值应变测试误差随杨氏模量增大也呈线性增大。对数值模拟得到的平均应变率测试误差和峰值应变测试误差实施二元线性回归分析,提出了SHPB试验中端面不平行岩石试件平均应变率和峰值应变的修正公式。     

小型平面振动筛分装置的设计与参数优化

为适应丘陵小田块农作物收获作业时清选分离的需要,设计了一款小型单风机单筛体、结构紧凑的平面振动清选装置。运用机械系统动力学分析软件(ADAMS),分析了筛体主要部件参数变化对其运动的影响规律;运用该软件的数值分析功能,对所设计筛分装置的结构参数进行了优化。结果表明:曲柄转速与曲柄长度是影响筛面加速度的两个最敏感因素;此款小型筛分装置的曲柄长度为25mm、转速为360r/min时,筛面加速度增加22%。     

基于 UKF 与互补滤波的随钻 IMU 井斜动态测量方法

针对随钻测斜仪安装在近钻头位置处受到的复杂冲击振动、钻柱旋转等干扰问题,提出一种基于无迹卡尔曼滤波（UKF）与互补滤波算法的随钻井斜动态测量方法。首先,利用限幅和低通滤波器滤除冲击噪声带来的加速度阶跃激励干扰信号和角速度高频干扰信号;然后,使用UKF滤除惯性测量单元（IMU）中加速度计和陀螺仪信号的大部分有色噪声;最后,建立加速度和角速度信息间的互补滤波器,滤除角速度信号的零偏噪声。仿真试验、复杂振动测试平台模拟实验及现场数据验证结果表明：钻具转速在0~300?r/min内时,井斜角整体测量精度在±?0.2?°以内;测量不受钻具转速与振动影响,实现了精准的随钻测斜。     

从共振衰减响应中提取微机械陀螺的骨架曲线

为测量微机械陀螺的非线性特性,研究了一种从共振衰减响应信号中提取骨架曲线的方法。采用Hilbert变换处理共振衰减信号,对所得到的瞬时幅值及瞬时频率曲线进行奇异谱分析,滤除信号中噪声引起的非理想波动,从而得到清晰易辨的骨架曲线,解决了基于Hilbert变换的非线性辨识方法对噪声敏感的问题。针对Duffing系统的数值仿真结果表明,这种方法比FREEVIB方法具有更好的抗噪声性能。对一种环型振动微陀螺进行了实验测试,所得到的骨架曲线、阻尼曲线以及频率响应曲线与传统扫频方式的测量结果有良好的一致性。作为一种通用测试手段,这种方法同样适用于其他微机械谐振元件动力学特性的实验测试。     

振动陀螺仪单向时滞耦合系统的摄动分析

针对振动陀螺仪单向时滞耦合系统，研究了角速度、耦合强度、耦合时滞与系统输出信号之间的关系，着重关注耦合时滞对待检测角速度测量结果的影响．本文采用摄动法对振动陀螺仪单向时滞耦合系统进行理论分析，得到了系统输出信号、系统振动边界和待检测角速度的近似表达式，并将数值和近似计算结果进行了对比．理论分析结果与数值结果比较吻合，验证了运用摄动法分析振动陀螺仪单向时滞耦合系统的有效性，也表明了在运用摄动法分析系统时具有局限性．     

旋转载体驱动硅微机械陀螺幅频特性

介绍了一种安装在旋转体上,用于旋转体姿态控制的新型微机械陀螺.陀螺利用旋转载体的滚转获得角动量,当载体发生偏航或俯仰,敏感质量块受到周期性哥氏力的作用,从而敏感载体的偏航或俯仰角速度.飞行试验中舵机的舵偏打容易使陀螺发生共振,陀螺输出信号无法满足旋转载体姿态控制的要求.针对这一问题,需精确测量陀螺的固有频率.首先基于陀螺运动方程分析了其幅频特性和固有频率,并利用数值计算软件进行了仿真,最后提出了一种对该陀螺幅频特性的测量方法,得到了幅频特性曲线,确定了固有频率70 Hz.实际测量的幅频特性曲线和仿真曲线一致,测量的固有频率相对于舵偏打产生的共振频率点误差为2.1%,通过避开测得的70 Hz 固有频率,获得了符合姿态控制要求的陀螺输出信号.     

Analyses of dynamic characteristics and structure optimization of tunnel boring machine cutter system with multi-joint surface

There will be structural failure in the cutter system with different degrees due to the vibration of cutters. Moreover, in the extreme environment, the dynamics behavior of the cutter system is hard to predict, and it is difficult to realize the anti-vibration design of cutters. Therefore, it is of great theoretical value and engineering significance to analyze the dynamics characteristics of tunnel boring machine (TBM) cutter system, optimize cutter structure, and improve the anti-vibration capability. In this paper, the typical TBM cutter systems are studied, based on the lumped mass method, a multi-degree of freedom coupling dynamics model of the TBM cutter system with multi-joint surface is established. Then, the model is verified by the cutter mount vibration experiment, and it is proved that the joint surfaces have a great influence on the vibration performance of cutter system. Finally, the vibration responses and loading transfer law of the cutter are analyzed, and a cutter structural optimization scheme is proposed. The optimization results show that the vibration and loading fluctuation of the upper and lower wedge block cutter mount are relatively smaller, and the cross section of upper wedge block is an isosceles trapezoid after optimization. The vertical vibration displacement of the cutter mount and the wedge block are reduced by \(\sim \)67 % and 53 %, respectively. The vibration damage of cutter system is greatly reduced. The research of this paper may provide a theoretical guidance for the structure design of the cutters.     

结构振动对大型激波风洞气动力测量的干扰

激波风洞起动过程形成冲击载荷激励测力系统的结构振动,气动力测量过程中振动尚未衰减,测力过程可以看作是一个动态的过程,激波风洞中天平输出信号包含了振动干扰的输出信号,现有的解决方法缺乏理论支撑,精度受限. 本文应用振动理论方法,得到了自由振动、强迫振动特性的基本解析结果. 自由振动特性研究中考查了单个振型对测力的干扰及其影响规律以及干扰量幅值随测力截面相对位置的变化规律. 强迫振动特性研究了不同载荷强迫振动下各阶振型对测力的干扰. 研究表明,由于干扰量幅值与加速度幅值的“零点位置” 不重合,传统加速度惯性补偿存在理论上的缺陷. 实验中确定干扰量主要来源需要综合考虑截面位置、载荷作用位置、载荷类型的影响.      

Full-field and point strain measurement via the inner surface of a rolling large lug tyre

Vehicle safety and performance can be dramatically improved if force or friction measurement of the tyre-terrain interface is known. Since the tyre-terrain interface is responsible for the majority of forces acting on the vehicle, this region has received a lot of attention in vehicle dynamics. Direct measurement of the tyre-terrain interface is difficult since it is hidden by the tyre and terrain. A lot of research has been conducted on the inside of tyre using accelerometers or strain gauges with research more focussed on passenger car tyres and very little work performed on agricultural tyres with larger lugs. This study performs strain measurements using point measurement, from strain gauges, and full field measurement, using a stereo camera measurement system, of the inside of an agricultural tyre on a drum test rig during vertical and lateral loading. Results show similar trends when compared to results on passenger car tyres, however the mounting of the strain gauge relative to the lug is shown to play a large role in the developed strain. Linear relationships between the applied tyre force and strain were obtained in different direction with R² values above 0.97.     

用于聚合物驱油的抽油杆动力学分析

聚驱井与水驱井相比杆管偏磨更加严重,聚驱井采出液的法向力是加剧偏磨 的重要因素之一. 根据非牛顿流体力学理论,采用上随体Maxwell模型,建立了法向力计算 模型,确定了井筒内法向力的分布规律,并将此法向力施加在抽油杆的瞬态动力学 模型中; 考虑实际边界条件,采用有限元法对聚驱抽油杆进行了分析计算. 并对FU081801 井模拟计算进行验证,模拟结果与作业检测结果吻合较好,证明了该方法的可行性. 通过此 方法可预测出聚驱井杆管的偏磨位置以及聚合物浓度对抽油杆偏磨的影响程度.     

大跨悬索桥抖振内力响应分析

基于虚拟激励法和有限元法,在频域建立了一种新的桥梁抖振内力响应分析的随机振动方法。该方法与传统随机振动方法相比具有如下两个特点:(1)单元抖振内力响应同时考虑了保留模态多模态耦合产生的动力效应和保留模态外高频模态产生的拟静力效应;(2)单元抖振内力响应同时考虑了单元杆端位移产生的单元杆端力和单元上分布荷载产生的单元固端力。以香港青马悬索桥为例,分析了保留模态多模态耦合产生的动力效应、高频模态拟静力效应、单元上分布荷载产生的单元固端力及主缆上的抖振荷载等因素对主梁抖振内力响应的贡献。结果表明:保留模态多模态耦合产生的动力效应对主梁抖振内力响应占据主导地位,高频模态拟静力效应、单元上分布荷载产生的单元固端力等因素对主梁抖振内力响应均有一定的影响,主缆上的抖振荷载对主梁侧向抖振内力响应有较大贡献。     

高速列车受电弓风洞试验研究

为了研究高速列车受电弓在较高速度下的整体气动特性、弓网接触压力以及受电弓对支持绝缘子的作用力等综合性能,在FD-09低速风洞中进行了测力试验。试验采用测力天平和力传感器进行测量。通过在FD-09风洞试验段内安装收缩地板的方式首次将受电弓试验风速提高到了380km/h,可以满足高速列车受电弓高速性能研究的需求。研究结果表明：受电弓相对列车运行方向对受电弓升力特性有显著的影响,对弓网接触压力也有较大的影响;通过调节导风板的角度可以有效控制弓网接触压力;受电弓对支持绝缘子的作用力表现为前面拉力后面压力。     

孔内起爆位置对爆破振动场分布的影响作用规律

岩石钻孔爆破中,孔内起爆位置决定炸药爆轰波的传播方向,进而影响爆破振动场的分布。通过分析柱状药包爆轰产物和爆炸能量的分配及其爆炸应力场的分布,揭示了起爆位置的影响作用机理;基于Heelan短柱解延长药包叠加计算模型,比较分析了不同起爆位置下爆破振动场的分布规律,并结合现场实验,验证了起爆位置对爆破振动场分布的调节作用效果。结果表明:起爆位置的影响作用机理在于柱状药包爆炸能量的轴向不均匀分配和爆破振动场叠加的相位延迟效应;孔内起爆位置对爆破振动场的分布起调节作用,爆破振动沿爆轰波传播正向叠加增强,且爆破振动场分布的不均匀性受药包长度和炸药爆轰速度的调控;对于常见的几种起爆方式,现场实验统计结果显示,底部起爆时地表爆破振动峰值最大,中部起爆次之,上部起爆最小,且爆破振动差异性随炮孔深度的增加而增大,但振动差异会随距离逐渐消减。     

Torsional vibration analysis of push-the-bit rotary steerable drilling system

Ordinary drillstring torsional vibration is a very common phenomenon that has been attracted great interesting. Through Measurement data, a series of studies and analysis of torsional vibration characteristics of the bottom hole assembly (BHA) have been developed. However, for rotary steerable system (RSS), especially push-the-bit mode, its drill torsional vibration phenomenon will demonstrate the new properties, because that the underground implementing agencies will generate cycle torque and drag to the BHA in the orientation process. This process is completely different to the previous. A set of “strap-down” measurement system was developed in this paper, and the triaxial accelerometer and triaxial fluxgate were installed near the bit. Proposed a method of solver drill bit rotation speed using real-time downhole measurement data (sampling frequency 100 Hz), and the torsional vibration mathematical model of push-the-bit RSS was established. We found that the torsional vibration phenomenon of push-the-bit RSS is more serious than the ordinary drilling system by downhole measurement data analysis, even in most cases manifested as stick-slip. The torsional vibration was divided into five different modes, which showing different statistical regularities. Corresponding analysis of the angular displacement and speed, we found that the drill bit always appears low-speed in the position of oriented. This is a strong proof of that the RSS implementing agencies pushing the BHA caused the drill bit torsional vibration more serious. This work is supplemented and development of the drill string torsional vibration studies. Contribute to the better understanding of the dynamics of the push-the-bit RSS. Put forward a new way of analysis the rotary steerable drillstring fatigue damage predicted, steering ability and the torsional vibration control.     

MEASUREMENT OF ADHESION FORCES IN AIR WITH THE VIBRATION METHOD

The vibration method represents a practical method for the measurement of adhesion forces and adhesion force distributions. This method causes sinusoidally altemating stresses and yields detachment and contact forces between particles and substrate of the same order of magnitude. Alternating contact forces of the vibration method can cause an adhesion force intensification through flattening of asperities. The measuring principle of the vibration method and the analysis of experimental results are described in the article. Normal adhesion forces (pull-off forces) are measured using the vibration method and the colloidal probe technique. The results of both methods show good agreement for small particle sizes. The influence of the detachment force direction is shown by comparing tangential and normal adhesion forces measured using particle reentrainment in a turbulent air flow and the vibration method, respectively. The surface roughness of the substrate and the relative humidity are shown to significantly influence the measured adhesion forces. For the calculation of the adhesion forces, an approach by Rabinovich was combined with approximations of plastic micro asperity flattening. The Rabinovich approach accounts for roughness effects on the van der Waals force by incorporating the rms roughness of the interacting surfaces. rms-values of the particles and substrates were measured with atomic force microscopy at different scanning areas.