实现包覆层无烟化应用的阻燃技术探讨

包覆层无烟化是实现固体火箭发动机排气低特征信号的重要措施之一。本文分析了包覆层生烟的原因，讨论了实现包覆层无烟化采用的阻燃技术。     

密封结构泄漏超声频谱特性分析影响研究

随着空间环境碎片日趋增多，航天器因碎片碰撞而发生泄漏的概率明显增大，这必然会影响航天器在轨运行寿命，亟需进行在轨泄漏超声频谱特性分析影响研究。因此，本文重点研究了探测距离、感知范围、检测方向、移动检测以及多层包覆层对不同尺寸漏孔泄漏超声频谱特性的影响规律。结果表明：空气传播的泄漏超声检漏方法可检测Ф0.3mm的泄漏孔，探测距离达500mm，检测方向角在±30°内，特征频率在37～43k Hz之间存在主峰，移动巡检定位精度可达±20mm以内；多层包覆层会对探测产生复杂影响，包覆层面积越大，检测灵敏度和强度越低。所研究成果具有一定普适性，可以为后续实施在轨堵漏措施提供技术支持。     

粉煤灰微珠-TiO_2复合颗粒制备与性能表征

以粉煤灰微珠为基体,利用TiOSO_4水解法,制备TiO_2包覆微珠复合颗拉。通过扫描电镜、X射线衍射、比表面积、超声振荡和光电子能谱等检测手段,对复合微珠的表面形貌、包覆层相组成、比表面积、包覆层与基体结合强度与结合方式进行了研究和探讨。检测与分析表明:得到的复合微珠表面包覆层为均匀非连续包覆,包覆层主要为金红石相,包覆后微珠比表面积比未包覆前提高了超过600倍,且包覆层颗粒与基体结合强度较高,二者间存在化学键的联结。     

降低聚氨酯包覆层修补率措施探讨

聚氨酯包覆层修补率较高,主要归结于包覆层易产生气泡。通过对聚氨酯包覆层气泡产生原因的分析,可归结为反应气泡和工艺气泡两大类;对消除气泡的措施进行了初步探讨,通过原材料处理、混料方式、固化剂选择及消泡剂的使用等因素的控制,可消除包覆层中的反应气泡。通过改善脱泡方式、脱泡程度、脱泡温度、包覆方式等工艺条件可消除聚氨酯包覆层中的工艺气泡。从而降低聚氨酯包覆层修补率,提高包覆质量。     

固体火箭发动机复合材料壳体承载力分析

为了提高固体火箭发动机(SRM)的外载荷承载能力,研究了其复合材料壳体的失效机制,提出了复合材料壳体的增强改进结构形式。通过提高复合材料外缠绕层的轴向刚度和横向弯曲刚度,使得连接区域内的内、外缠绕层的轴向变形相协调,改善了内、外缠绕层的轴向承载分配,使增强改进后的复合材料壳体结构的承载能力提高了124%,而结构质量增加低于10%。研究结果表明: SRM复合材料壳体承载能力的关键因素是连接区域内复合材料内、外缠绕层的刚度匹配设计,只有保证连接区域内的刚度匹配和位移变形相协调,才能充分发挥复合材料壳体的承载能力。     

配橡胶内衬复合材料板壳的敲击法无损检测

配橡胶内衬的复合材料板壳可以模拟真实纤维缠绕压力容器。本文通过比较复合材料被撞击的时间历程和频域曲线,检测了复合材料缠绕层与内衬之间、内衬与内衬之间的损伤区,并对某型火箭发动机壳体的缩小比例试件进行了实际检测。     

H_2O_2处理碳包覆铁纳米颗粒的表面特性及分散行为

采用体积分数30%的H2O2处理碳包覆铁纳米粒子外层的非晶态类石墨碳层,并将其超声分散于水介质中,通过改变pH值分析测定碳包覆铁纳米粒子表面zeta电位和粒径。结果表明:碳包覆铁纳米粒子非晶碳层的特殊结构可通过双氧水化学处理使其表面产生羧基和羟基;在强碱性介质下,羟基和羧基可强化颗粒间的静电斥力,提高碳包覆铁纳米粒子在水介质中的分散性能。当pH值约为11.5时,碳包覆铁纳米粒子表面zeta电位为48 mV,水合粒子粒径可达到110 nm。     

用应力波技术对配橡胶内衬的复合材料板壳进行无损检测

配橡胶内衬的复合材料板壳可以模拟宇航飞行器的纤维缠绕压力容器。本文提出用应力波技术(Stress wave)对复合材料构件的损伤进行无损检测,并实际检测了配橡胶内衬的复合材料板壳内衬与复合材料缠绕层之间、内衬与内衬之间的损伤.绘出了损伤区的幅频特性曲线,确定出损伤区在橡胶内衬的分布情况。最后,作者对某型火箭发动机的缩小比例圆柱壳体进行了实际检测,并获得了满意结果。     

ZrWMoO_8粉体处理工艺对铜包覆效果的影响

采用水合前驱体分解法成功制备出高纯棒状钨钼酸锆(ZrWMoO8)粉体。在超声环境下采用化学镀方法对自制的ZrWMoO8粉体进行铜包覆。研究了温度对镀液稳定性的影响,探讨了粉体表面处理工艺对包覆效果的影响,利用扫描电子显微镜(SEM)观察镀层微观形貌,并用能谱(EDS)分析镀层的元素组成。实验结果表明,室温环境下可保证镀液的稳定性;粉体经敏化活化后,可在ZrWMoO8粉体表面成功镀覆上一层比较致密的铜单质,经计算,包覆Cu与ZrWMoO8的质量比为1∶1。     

固体火箭发动机纤维壳体缠绕张力校准系统设计

通过对某厂固体火箭发动机纤维壳体缠绕成型生产过程的实地调研和分析,结合生产现状介绍了固体火箭发动机壳体成型工艺中的工艺指标、参数的制定及控制方法,提出了固体火箭发动机纤维壳体缠绕过程中的张力校准解决方案。主要通过检测到的张力数据计算张力静差率和张力波动率,以便更好地了解缠绕机的实际工作情况,进一步对缠绕工艺进行分析。     

Standing wave bi-directional linearly moving ultrasonic motor

A standing wave bi-directional linearly moving ultrasonic motor has been studied for the purpose of implementing a practical linear ultrasonic motor with simple structure, simple driving and high resolution. The fundamental principle of this linear motor is projections on the right sides of a standing wave crests generating thrust force right-diagonally on the slider pressed against the projections. Correspondingly, projections on the left sides of the wave crests make the slider move toward the left. In order to realize bi-directional actuating, vibration mode B3 or B4 is excited in a rectangular plate-type vibrator to make the projections on the right sides or the left sides of the wave crests. In this paper, the operation principle of the linear motor is demonstrated. Furthermore, a prototype linear ultrasonic motor of 40 mm in length, 10 mm in width is fabricated and investigated. The following performances have been achieved: maximum speed 200 mm/s, maximum force output 150 gf, and resolution less than 0.1 mum.     

Wear and dynamic properties of piezoelectric ultrasonic motor with frictional materials coated stator

Piezoelectric ultrasonic motors have been studied, developed and utilized by researchers and companies all over the world. Ultrasonic motors (USM) produce rotational motion based on traveling waves made by the resonant vibrations of piezoceramic. These motors have been recently developed and utilized in practical applications. The dynamic properties and life of piezoelectric ultrasonic motors are strongly related to the frictional material Fused on the sliding surface. In this study, effects of frictional material properties on the performances of piezoelectric ultrasonic motors are investigated. It was possible to improve the torque of a traveling wave type ultrasonic motor by stator's coating.     

杆式行波超声电机运动机理的研究

本介绍了作发展的一种杆式行波超声电机的结构。基于振动和波动理论，深人研究了杆式行波超声电机的运行机理，推导了定子端面上任意质点运动轨迹，证明了在一定的激励条件下，定子端面沿Z向、径向和周向都可形成行波。描述了定子端面某些点的运动轨迹的空间分布。还提出了定、转子问最佳接触角和有效椭圆的概念。这些都为设计高效率的杆式超声电机提供了理论依据。     

A piezomotor using longitudinal actuators

A new travelling wave type ultrasonic motor has been developed which uses longitudinal piezoelectric actuators to generate a progressive wave on the surface of a metallic ring. The rotor, which moves through frictional force, is pressed on this elastic plate. This paper deals with the motor construction and its characteristics. Theoretical modelling and experimental performances obtained with the motor prototypes are reported. A maximum of 0.8 Nm and a no-load rotation speed of 120 rpm have been obtained with a double rotor prototype. The results indicate that this piezomotor is proved to operate successfully at a mechanical output power of 4 W.     

纵振换能器式圆筒型超声电机振动特性的研究

以纵振夹心换能器式圆筒型超声电机为研究对象,对换能器的振动状态进行了分析,给出了换能器弯曲振动的产生原因;研究了耦生弯振对电机机电耦合系数以及圆筒中弯振行波质量所带来的影响,耦生弯振的存在使得定子模态特征频率偏离换能器谐振频率,并使得定子圆筒中的弯振行波产生了畸变。最后,提出一种采用换能器弯振激励圆筒径向弯振的模态组合方式。     

用于瞬态高温测试超声波传感器

目的　研究一种用于测试瞬态高温的传感器 .方法　设计超声波发射和接收装置用来测量超声波声速 ,根据超声波的相关原理 ,声速的大小可以反映被测气体的温度值 .结果与结论　超声波瞬态高温传感器是一种非接触式测量传感器 ,动态响应好 ,可用于气轮机进气、火箭排气、汽缸燃烧气体、火炸药爆破燃烧等场合的温度测试     

Ultrasonic motors using piezoelectric ceramic multimode vibrators

The development is reported of an ultrasonic motor using piezoelectric ceramic multimode vibrators consisting of circular or annular plates in which degenerate horizontal vibration modes of the same or different form are used. Two orthogonal nonaxisymmetric vibration modes were used in the same-form case, and the combination of a nonaxisymmetric vibration mode and a radial vibration mode was used in the different-forms case. Some details of the motor design and its experimental characteristics are presented. The ultrasonic motor presented here has a special advantage in its thin construction.     

Estimation of Thermal Contact Resistance Using Ultrasonic Waves

In this paper, numerical simulations of both the three-dimensional heat conduction and two-dimensional elastic wave propagation at the interface of contact solids have been carried out. Numerical results of heat conduction simulations show that both the true contact area and thermal contact conductance increase linearly with an increase in the contact pressure. Numerical results of the ultrasonic wave propagation show that the intensity of a transmitted wave is very weak but depends clearly on the contact pressure. On the other hand, the intensity of reflected wave amounts to more than 99% of the standard reflected wave that results from the case of one cylindrical specimen without contact. However, the intensity of the modified reflected wave defined by the difference between the reflected wave and standard reflected wave shows the same tendency as that of the transmitted wave. The intensities of both transmitted and modified reflected waves could be expressed by the same power function of the contact pressure. By comparing the results of heat conduction with those of ultrasonic propagation calculations, a power functional correlation between the thermal contact conductance and transmitted or modified reflected intensity has been obtained. Using this correlation, it will be possible to estimate the thermal contact conductance between two solids through measuring the intensity of either reflected or transmitted ultrasonic waves.Paper presented at the Seventh Asian Thermophysical Properties Conference, August 23–28, 2004, Hefei and Huangshan, Anhui, P. R. China.