Comparison of drilled hole quality evaluation in CFRP/CFRP stacks using optical and ultrasonic non-destructive inspection

In aeronautical industry, stringent requirements relate to the quality of drilled holes in carbon fiber reinforced plastic (CFRP) composite laminates as low hole quality determines poor assembly tolerance, structural properties reduction, and risk for long-term part performance. Non-destructive quality control techniques were applied to drilled CFRP laminate stacks for aeronautical applications to characterize the material damage induced by drilling in order to assess the hole quality for product acceptability. Experimental metrology procedures, including optical measurements and ultrasonic non-destructive evaluation, were employed to appraise both external and internal induced material damage in holes machined under diverse drilling conditions. The optical inspection procedure, comparable to the visual inspection method regularly utilized in industry, provided delaminated area evaluations that are underestimated in the case of severe drilling conditions by up to 7% for hole exit and up to 5% for hole entry. In the case of less severe drilling conditions, the underestimation was limited to <2.5% for both hole exit and hole entry, which can be considered a practically negligible disparity.     

纳米流体制备的研究进展

综述了纳米流体制备的一些研究成果,总结了目前主要的纳米流体制备方法,分析了制备纳米流体过程中的影响因素,认为超声分散并辅之以分散剂的混合制备法是实验研究中较为实用可行的方法;pH值、分散剂类型及用量是影响纳米流体分散稳定性的主要因素.展望了纳米流体制备方法的发展方向及超声分散法所要综合考虑的因素.     

频率修正在超声变幅杆设计中的研究与应用

超声变幅杆在沿轴线方向作纵向振动时,由于存在泊松效应,纵向振动会引起变幅杆沿径向方向的横向振动。传统变幅杆在设计过程中,忽略横向振动的影响则会导致计算出的谐振频率高于实际频率。为了让变幅杆理论设计谐振频率与实际频率相符合,分别对简单圆柱杆和阶梯形变幅杆进行研究,推导出常用半径比范围内简单阶梯形变幅杆的频率修正公式,使其满足设计和使用要求,并可以减少能量传输过程中的能量损耗。     

TiO2催化超声波降解钻井污水中CODCr技术研究

为寻求有效降解钻井污水CODCr的新方法,探讨了超声波及超声波和纳米TiO2联合降解钻井污水CODCr的效果,研究了各种因素对超声波催化降解钻井污水中CODCr的影响.在纳米锐钛型TiO2的作用下,二氧化钛超声波催化降解钻井污水的CODCr效果明显优于单纯使用超声波的降解.在超声波频率20 kHz,输出功率为50 W,TiO2催化剂投加质量浓度为0.5～1.0 g/L,pH为3.0,温度为30 ℃,钻井污水的CODCr初始浓度1 881.04 mg/L的条件下,80 min超声波催化处理后的CODCr降解率＞99.1%.     

Surface acoustic wave characterization of a thin, rough polymer film

Laser generated surface acoustic waves (SAW) in a heterodyne diffraction scheme is a powerful technique for elastic characterization of thin films and it is frequently used on samples of high optical quality. We show that the method can also be effectively used in difficult conditions, on rough samples. Measurements are presented on a 3 µm thick film of polymer, spin-coated on steel, and on the same sample after addition of an aluminum coating. The experimental data are interpreted using a model assuming a stack of perfect layers. The analyses show good consistency within the SAW results for both configurations, and consistency with nano-indentation results, cross-validating both approaches.     

复合型超声马达

介绍一种纵振－扭振复合式超声马达，同时给出了相应有等效电路分析方法以及马达工作特性的测量结果。该马达的最大机电转换效率为４．１３％。     

超声波在电沉积制备超细金属粉末中的应用

电解法是制备金属粉末的一种重要方法，但其传统制备过程所得到的粉末颗粒较粗且容易团聚。综述了超声波的物理和化学效应，对其在电沉积技术中应用的机理作了较为全面的阐述，总结了这一领域的研究现状，并对发展前景作了展望。功率超声可有效解决电沉积中超细粉末在镀液中的分散问题，并抑制晶粒长大，因而超声波的引入为电沉积制备超细金属粉末提供了更有效的手段，对实现超细粉末的工业化生产有重要的促进作用。     

Ultrasonic Imaging of Porosity Variations Produced During Sinteriing

A silicon carbide disk was sintered from 2090° to 2190°C in 25°C steps. After each sintering step, the disk was examined using a precision acoustic scanning system to determine acoustic attenuation and velocity. The bulk density was found to vary non-monotonically with sintering temperature. The density varied as much as 10% from its value at 2090°C during the sintering process. Local density fluctuations occurred in an organized and history-dependent way. These local density fluctuations varied up to ±7% of the bulk density and were made visible by acoustic attenuation and velocity mapping.     

Use of Ultrasound to Determine Cod Fillet Composition

The relationships between the composition and ultrasonic properties of Atlantic cod (Gadus morhua) fillets were examined. The lipid, protein, moisture and ash contents of cod fillets were determined by official methods. The ultrasonic velocity and attenuation coefficient of the fillets were measured using a pulse-echo technique. The ultrasonic velocity of the fillets varied between 1575 and 1595 m s^?1, decreasing linearly with increasing moisture content (r² > 0.8 for 26 samples). No systematic relationship was observed between the attenuation coefficient and moisture content. Our experiments highlight the potential of using ultrasonic velocity measurements to rapidly and nondestructively determine the moisture content of cod fillets (and possibly their protein content by deduction).     

基于TDC-GP21高精度三维测风系统设计

针对快速准确测量风速和风向的问题,采用TDC-GP21高精度时间测量芯片和MSP430F413单片机控制芯片,设计了三维超声波测风系统。利用三对超声波换能器构成三维阵列,采用时差法测量风速和风向。该文介绍了三维超声波测风系统总体结构,超声波驱动电路和超声波接收电路以及风速和风向测量的软件流程。