金属表面粗糙度对热红外偏振特性影响研究

根据热红外偏振的原理和探测方法,利用一种热红外偏振探测系统分别研究了铝质和钢质金属板热红外偏振度和其表面粗糙度之间的关系.金属板的表面粗糙度通过喷砂和刨床加工控制.实验结果分析表明:在观测角较小时,喷砂方式处理的金属目标板,粗糙度对它们的热红外偏振度影响较小；而刨床加工的金属目标板,粗糙度对它们的热红外偏振度影响较大.在观测角较大时,无论经过何种加工方式处理表面的金属目标板,都遵循表面越是光滑其热红外偏振度越大的规律.     

高速气流作用下能量加载金属蜂窝板数值模拟

数值模拟研究了高速气流作用下能量加载金属蜂窝板温度场。针对金属蜂窝典型单元,构造了蜂窝核细观导热数值计算分析模型。采用流固耦合计算方法,使用两相流模型和凝固/熔化模型模拟气流对烧蚀物的剥蚀,较完整地模拟了能量加载金属蜂窝板的物理变化过程,计算得到了金属蜂窝板的温度分布以及烧蚀形貌。结果表明两相流方法能够较全面地模拟能量加载金属蜂窝板过程中的对流换热、熔化与凝固过程以及金属液体在气流冲刷下的动力学过程,能获得较为合理的物理图像。     

用于红外探测器的高红外吸收率结构研究进展

高红外吸收是实现高灵敏度红外探测器的一个重要途径。探测器的响应率与热吸收率紧密相关。高红外吸收将提升红外探测器的探测性能。鉴于高吸收率的重要性,对国内外研究中典型的高红外吸收结构的研究进展进行介绍。目前典型新型高吸收结构有基于新型材料(如超材料)的高吸收结构和基于金属光栅高吸收结构。研究表明这些结构在某些波段可实现近100%的完美吸收,是发展高灵敏探测器的新途径。     

使用氟化钡作为固定相的薄层色谱-红外光谱联用研究

原位薄层色谱-红外光谱联用在分析复杂混合物七有巨大潜力,但因固定相自身的红外吸收严重干扰样品检测,该方法进展缓慢.本文应用对中红外光透明的氟化钡微小颗粒作为固定相制备薄层层析板,并对该板的层析效果及原位显微反射红外光谱检测的可行性进行了初步的探讨.通过优化反应条件,制备出粒径为500nm左右的氟化钡颗粒;发展出一种制备薄层层析板的新技术——沉降-挥发法;通过实验证明,新型薄层板具备分离混合物的能力;原位红外光谱检测结果表明氟化钡作为固定相不干扰样品的检测.应用氟化钡作为新型薄层板固定相,为从技术上实现原位薄层色谱-红外光谱联用打开了大门.     

铝酸盐类发光材料红外释光的研究

报道了铝酸盐类发光材料体系存在高效率的红外释光现象,成功地合成出对红外光束反应灵敏的铝酸盐类发光材料,研制出红外激光检测板,同时研究了该类发光材料红外与紫外发光及其荧光衰减特性,提出了该类发光材料的红外发光应属于红外释光过程,并展示了其实际应用前景。     

铝合金板疲劳微裂纹超声红外成像检测的数值及实验研究*

超声红外成像检测技术是一种发展迅速的新型无损检测技术,可用于检测材料表面或近表面的缺陷,由于对缺陷具有选择性加热的特点,近年备受检测行业的关注。在铝合金板中制作疲劳微裂纹,在板中激励声波,裂纹表面因振动摩擦生热,用红外摄像仪记录板表面温度分布。拍摄的红外图像序列经傅立叶变换后得到的幅值和相位图能清晰显示裂纹的特征,测量到的裂纹长度误差达到4.3%。用有限元模拟超声在板中裂纹处的生热过程,研究板中超声在裂纹处的励热机制。超声的激励时间、裂纹表面间的摩擦系数和裂纹开口宽度直接影响裂纹处的励热效果,温度最高通常位于裂纹尖端附近。实验和模拟结果均表明超声红外成像检测技术能对板中疲劳微裂纹实现快速检测,提供有效、可信的检测结果。     

用红外测温仪观察二极管板流引起的阴极降温现象

为了观察由板流引起的灯丝温度下降现象,利用红外测温仪对理想二极管灯丝温度作了精密测量。由于忽略了板流,导致阴极灯丝温度下降,致使测得的金属逸出功存在着大约-1.86%的系统相对误差。实验验证了当灯丝电流和板流较小时,测不出灯丝温度随板流的变化。当灯丝电流为0.74A以上时,可以明显地观察到输出板流后,灯丝温度要比板流为0时低（1～2）K,此结果与预测值十分相符。     

金属-绝缘体-半导体器件红外探测机理研究

建立金属-绝缘体-半导体器件反型层子能带结构的势理论模型,并由此模型研究了金属-绝缘体-半导体器件红外探测器的工作机理及制作的关键. 关键词：     

红外和拉曼光谱在金属氢化物结构分析中的应用

红外光谱和拉曼光谱是分析金属氢化物结构的强有力工具,通过红外、拉曼光谱分析并结合理论计算,可以获得二元(MgH₂,CaH₂,AlH₃)和三元(Mg₂FeH₆)金属氢化物中金属原子与氢原子局域成键环境信息,从而鉴别金属氢化物不同的相结构,还可以获得三元金属氢化物M₂RuH₆(M=Ca,Sr,Eu)中由于金属原子的不同而导致的结构差异,以及三元金属氢化物与其氘化物的结构差异。利用原位拉曼光谱分析技术分析高压或高温下金属氢化物的形成与分解反应过程,可以获得金属氢化物在高压加载及卸压过程中的结构变化,更好的理解金属氢化物的衍射数据。PAIR(photoacoustic infrared spectroscopy)光谱技术增强了红外活性和拉曼活性组合谱带的强度,从而避免了空气及潮湿环境对傅里叶红外变换光谱实验结果的影响。红外光谱和拉曼光谱用于金属氚化物的结构分析,获得金属氢化物中金属原子与氢同位素原子局域成键环境的差异,更好的研究氢同位素效应。而且,拉曼光谱已被成功用于分析氢同位素混合气体的组成。因此,将金属氢化物结构的红外和拉曼光谱分析与氢同位素气体组分的拉曼光谱分析相结合,可用于研究金属与氢同位素气体反应的动力学过程及同位素效应。     

基于碘化银固定相的薄层色谱-红外光谱联用研究

在分析复杂混合物方面原位薄层色谱-红外光谱联用有巨大潜力,二者联用能够相互取长补短,极大地提高对复杂混合物的解析能力。但因固定相自身的红外吸收能够对样品的检测造成干扰,使该方法进展缓慢。实验应用对中红外光透明的碘化银纳米微粒作为固定相制备薄层层析板,并对碘化银薄层板的层析效果及原位红外光谱检测的可行性进行了初步的研究。通过正交设计实验法优化反应条件,制备出粒径为100 nm左右的碘化银颗粒;应用沉降-挥发法制备薄层层析板,实验表明该薄层板具备分离混合物的能力,且原位红外光谱检测结果表明碘化银作为固定相不干扰样品检测。     

金属蜂窝夹芯结构抗水下冲击性能

为揭示高强度水下爆炸冲击载荷作用下金属夹芯结构的抗冲击性能,在实验室开展小尺寸水下爆炸加载技术对金属蜂窝夹芯结构性能影响的实验研究。基于实验结果,开展了全尺寸数值模拟金属蜂窝夹芯结构在水下冲击载荷作用下的动态响应和抗冲击性能研究。结果表明,数值模拟、实验和理论模型计算的结果具有良好的一致性。由于蜂窝芯材相对密度对夹芯结构能量耗散方式和载荷传递机制的影响,结构动态响应、失效模式以及抗冲击性能随着冲击强度的变化表现出较为明显的不同。通过抗冲击参数分析,建立了反映金属蜂窝夹芯结构抗冲击性能的结构横向变形、固支反力、透射脉冲和塑性能耗随冲击强度和芯材相对密度变化的结构-载荷-性能量化关系。     

Analytical Study on the Rate of Sound Transmission Loss in Single Row Honeycomb Sandwich Panel Using a Numerical Method

Honeycomb structures have recently, replaced with conventional homogeneous materials. Given the fact that sandwich panels containing a honeycomb core are able to adjust geometric parameters, including internal angles, they are suitable for acoustic control applications. The main objective of this study was to obtain a transmission loss curve in a specific honeycomb frequency range along with same overall dimensions and weight. In this study, a finite element model (FEM) in ABAQUS software was used to simulate honeycomb panels, evaluate resonant frequencies, and for acoustic analysis. This model was used to obtain acoustic pressure and then to calculate the sound transmission loss (STL) in MATLAB software. Vibration and acoustic analysis of panels were performed in the frequency range of 1 to 1000 Hz. The models analyzed in this design includes 14-single row-honeycomb designs with angles of −45°, −30°, −15°, 0°, +15°, +30°, +45°. The results showed that a-single row and −45°cell angle honeycomb panel in the frequency range of 1 to 1000 Hz had the highest STL as well as the highest number of frequency modes (90 mods). Furthermore, the panel had the highest STL regarding the area under the STL curve (dB∙Hz). The panels containing more frequency mods, have a higher transmission loss. Moreover, the sound transmission loss is more sensitive to the cell angle variable (θ). In other studies, the STL was more sensitive to the number of honeycomb cells in the horizontal and vertical directions, as well as the angle of cells.     

各向异性蜂窝夹芯材料的电磁传输性能分析算法研究

蜂窝夹芯结构作为天线罩最常用的透波材料, 其电各向异性特征对电磁传输性能具有不可忽略的影响. 本文基于各向异性蜂窝夹芯材料对电磁波水平极化和垂直极化分量的有效介电常数, 建立了多层蜂窝夹芯材料的等效传输线网络传输方程, 并给出了其传输系数的计算公式.该计算公式由于考虑了材料的三维各向异性特征, 不仅理论上可以计算多层各向异性介质板对任意方向入射电磁波的传输系数, 而且能够揭示出材料方向角对传输性能的影响规律.同时, 通过传输线网络等效, 其计算效率远高于有限元等方法.数值算例表明, 本方法能够有效地揭示蜂窝夹芯材料的各向异性对其传输性能的影响, 计算结果在入射角为0°–80° 时与有限元法符合很好. 关键词： 电磁传输性能 电各向异性介质 蜂窝夹芯材料     

Assessment of sandwich models for the prediction of sound transmission loss in unidirectional sandwich panels

The consistent higher-order approach and the two-parameter foundation formulation are used for the derivation of sound transmission loss in symmetric unidirectional (infinitely wide) sandwich panels with isotropic face sheets. In both models, transmission loss is calculated using decoupled equations representing symmetric and anti-symmetric motions of a sandwich panel. The closed-form expressions for impedances and transmission coefficient of a symmetric sandwich panel with an isotropic core are derived for the two-parameter foundation model. A comparison between the numerical predictions based on the two sandwich models and available experimental data shows that the consistent higher-order formulation can be used to predict the transmission loss in symmetric sandwich panels with both honeycomb and isotropic cores. For prediction of transmission loss of symmetric sandwich panels with an isotropic core, the two-parameter foundation model is more convenient, while the consistent higher-order approach is more accurate.     

Non-destructive inspection of drilled holes in reinforced honeycomb sandwich panels using active thermography

The aerospace industry is in constant need of ever-more efficient inspection methods for quality control. Product inspection is also essential to maintain the safe operation of aircraft components designed to perform for decades. This paper proposes a method for non-destructive inspection of drilled holes in reinforced honeycomb sandwich panels. Honeycomb sandwich panels are extensively employed in the aerospace industry due to their high strength and stiffness to weight ratios. In order to attach additional structures to them, panels are reinforced by filling honeycomb cells and drilling holes into the reinforced areas. The proposed procedure is designed to detect the position of the holes within the reinforced area and to provide a robust measurement of the distance between each hole and the boundary of the reinforced area. The result is a fast, safe and clean inspection method for drilled holes in reinforced honeycomb sandwich panels that can be used to robustly assess a possible displacement of the hole from the center of the reinforced area, which could have serious consequences. The proposed method is based on active infrared thermography, and uses state of the art methods for infrared image processing, including signal-to-nose ratio enhancement, hole detection and segmentation. Tests and comparison with X-ray inspections indicate that the proposed system meets production needs.     

Design and mathematical modelling of the space-borne far-infrared Fourier transform spectrometer for REFIR experiment

A far infrared Fourier spectrometer named REFIR (Radiation explorer in the far infrared) has been designed for space-borne observations of the atmospheric radiance in the broad spectral range 100–1000 cm⁻¹. The requirements are discussed and the adopted instrumental configuration is presented. The variability of the source and the narrow frequency bandwidth of the detectors as well as some novel features of the selected configuration require some dedicated analysis for the establishment of the instrument performances which are herewith described.     

Distortion-free single point imaging of multi-layered composite sandwich panel structures

The results of a magnetic resonance imaging (MRI) investigation concerning the effects of an aluminum honeycomb sandwich panel on the B1 and B0 fields and on subsequent image quality are presented. Although the sandwich panel structure, representative of an aircraft composite material, distorts B0 and attenuates B1, distortion-free imaging is possible using single point (constant time) imaging techniques. A new expression is derived for the error caused by gradient field distortion due to the heterogeneous magnetic susceptibility within a sample and this error is shown not to cause geometric distortion in the image. The origin of the B0 distortion in the sample under investigation was also examined. The graphite-epoxy 'skin' of the panel is the principal source of the B0 distortion. Successful imaging of these structures sets the stage for the development of methods for detecting moisture ingress and degradation within composite sandwich structures.     

Surface cleaning of metal wire by atmospheric pressure plasma

In this study, the possible application of atmospheric pressure dielectric barrier discharge plasma for the annealing of metallic wire is examined and presented. The main purpose of the current study is to examine the surface cleaning effect for a cylindrical object by atmospheric pressure plasma. The experimental setup consists of a gas tank, plasma reactor, and power supply with control panel. The gas assists in the generation of plasma. Copper wire was used as an experimental cylindrical object. This copper wire was irradiated with the plasma, and the cleaning effect was confirmed. The result showed that it is possible to remove the tarnish which exists on the copper wire surface. The experiment reveals that atmospheric pressure plasma is usable for the surface cleaning of metal wire. However, it is necessary to examine the method for preventing oxidization of the copper wire.     

Study of the performance of a thermoelectric generator transformation of the thermal energy conveyed by a heat transfer fluid into electrical energy

A mathematical model to predict the maximum energy conversion efficiency of the thermoelectric generator is developed to improve the performance and maximize the energy conversion efficiency of the thermoelectric power generator. The studied device corresponds to an original configuration of thermoelectric modules mounted on the peripheral surfaces of two channels, one of the channels is crossed by hot fluid and the other by a cold fluid. First, the effect of the flow rate was studied to choose the flow rate adapted to our study for three different configurations of the thermopile, the co-current configuration, the counter-current configuration, and the sandwich configuration. Then a comparison was made to choose the best configuration between these three studied configurations by addressing their thermoelectric performances. The results revealed that the sandwich configuration is much better than the co-current and counter-current configurations and reduces the surface area occupied by the TEG by half while generating more power than a solar panel.