复合材料预制体单边弯针缝合装备技术研究

三维缝合技术不仅能够显著改善复合材料的层间性能,提高其抗分层性和抗冲击损伤容限,结合液体成型工艺,还可以实现复合材料结构整体化成型。本文以复合材料单边缝合技术为研究背景,开展复合材料单边弯针缝合装备技术的研究。首先从分析单边弯针缝合装备的功能需求和平台总体规划方案入手,设计并制造出一种单边弯针缝合头;然后针对该类缝合线迹的稳定化成型因素进行了讨论与分析,确定了在单个缝合周期内缝合头末端执行部件之间相互协调的位移时间关系曲线,确定了最佳线环形态以及缝线供需平衡关系表达式;最后通过试缝试验证明该缝合装备对纤维预制体的缝合能够形成平滑稳定的链式线迹,并最终实现良好的缝合效果。     

复合材料单面双线缝合装置的设计

通过对复合材料的缝合技术和缝合特点的概述,发现目前双面缝合以及单面缝合技术存在的问题和不足,然后结合现有的OSS单面缝合和传统的双面锁式缝合技术的优点,提出了单面双线缝合技术,并基于该技术的缝合动作利用建模软件Solid Works对缝合装置进行了详细的设计,该技术对纤维复合材料铺层的缝合能够形成平滑稳定的类似改良式锁式线迹。最后通过Adams进行运动仿真,验证了各机构能够按规律配合完成缝合动作,证明了缝合装置设计的可行性。     

双头铺放轨迹后处理技术研究

为提升自动铺放装备工作效率并提高铺丝机工作的灵活度,对双机器人协同的类转体构件铺丝成型技术进行研究,提出了一个满足协调约束的轨迹预选机制。在确定了双机器人横向移动的配合方案后,以机器人平台可达空间的限制作为约束条件,通过夹角控制对铺丝轨迹进行配对编码并验证。同时得到完整模具的轨迹分配方案,将CAD软件生成的铺放信息转化成机器人角度的加工文件。文中模型证明所提方法满足大型类回转体构件铺放生产的工艺要求,大大提高了铺放效率。     

碳纤维外壳的制造方法

正本发明公开了一种碳纤维外壳的制造方法,包括步骤:将单向碳纤维预浸料叠层排布形成内层和中间层,中间层上的单向碳纤维预浸料与内层上的单向碳纤维预浸料呈0°的夹角;将碳纤维平纹布预浸料铺设在中间层上形成外层;内层、中间层和外层形成预成型原料;将预成型原料放入模具中并按预设的成型条件固化成型,形     

斜针翅管换热器数值模拟

以水和柴油为换热对象,利用三维模型对2种不同规格的直针翅管以及30°,45°和60°的斜针翅管换热器的壳程温度场、压降和传热性能进行了模拟;并将斜针翅管、直针翅管与光滑管进行了比较。模拟结果表明,斜针翅管的压降是光滑管的1.06～1.4倍,是直针翅管的0.96～1倍,其总传热系数约是光滑管的1.7～3倍,以及直针翅管的0.85～0.93倍。从模拟结果看,β在大约30°存在一个合适的倾斜角,其综合换热性能较好。     

双腔自激振荡器结构优化分析

以双腔自激振荡器为研究对象,通过工程流体模拟软件建立了双腔自激振荡器模型。并且针对不同结构的双腔自激振荡器的自激震荡效果进行仿真模拟,边界条件采用压力入口并且设定初始压力为10 MPa,对比二级谐振腔碰撞角α分别为90°、105°、120°、135°、150°、出口直径d_3分别取4.6、5.0、5.4、5.8、6.2 mm、二级谐振腔腔径D_2分别取30、35、40、45、50 mm等不同工况进行了仿真分析,通过观测峰值速度,对比速度云图得到双腔自激振荡器最优的结构参数。     

定热流边界下重力作用PCM熔化过程规律

为提升相变储热单元的相变材料（PCM）熔化速率,本文定义基于热源输入方向与重力方向的通用坐标,建立可视化实验装置与数学模型,探究定热流边界下夹角γ对方腔内PCM熔化的作用规律。结果表明,当夹角γ从0°增加到180°时,PCM熔化时间先增加后减少,最后轻微上升。当夹角γ为0°时,PCM以纯导热完成熔化;夹角为15°时,对应的熔化时间最长,相对纯导热过程增加了40.32%;夹角为120°时,对应的熔化时间最短,相对纯导热过程减少了63.11%。当夹角较小时,自然对流对PCM的整体熔化过程有抑制作用,只有在夹角大于一定数值时,自然对流才能促进PCM的熔化过程。此外,多工况下获取的最优夹角γ均在90°~180°,且相对更趋近90°。所以在实际工程应用中,规整相变储热单元的热源端最低点应该低于PCM端最低点。     

尺桡骨干双骨折放射下闭合复位克氏针内固定术的临床观察

目的探讨尺桡骨干双骨折放射下闭合复位克氏针内固定术的临床疗效。方法选择本院2004年6月以来对45例尺桡骨干双骨折患者行放射下闭合复位克氏针内固定术,观察疗效。结果随访6～12个月,44例术后功能恢复良好,无后遗症,1例并发骨不连。治愈率达97.7%。结论尺桡骨干双骨折放射下闭合复位克氏针内固定是一种经济、微创、疗效满意的治疗方法。     

双喷嘴喷射成形柱状坯生长过程模拟

建立了双喷嘴喷射成形柱状坯形成过程数学模型,利用此模型,对下拉速度、喷射夹角和初始偏心距3个工艺条件下沉积柱状坯的生长过程进行了数值模拟,模拟结果表明,各条件对柱状坯形成过程都有影响,只有合理的工艺条件才可得到较合理的柱状沉积坯.通过理论分析,提出了得到稳定增长理想柱状坯的条件,对优化工艺有一定指导意义.     

深槽带钩类零件批量镀铬挂具的设计

通过设计一种一字前后夹板型组合挂具来实现槽针的批量镀铬。受制于槽针的结构特点,没有合适的批量镀铬挂具。同时,批量镀铬时容易出现过烧、结瘤等现象。对此,设计了一种组合挂具,不仅加以引流铜丝和物理屏蔽遮挡板设计,还改进了阳极板与挂具的相对位置并隔离了超出的阳极。实验结果表明:该组合挂具能实现槽针的批量镀铬;辅助阴极设计在很大程度上改善了针钩处的烧焦现象,针槽内壁及针钩处都能获得一层光亮、平滑的镀铬层;槽针批量镀铬后的合格率在95.0%以上。     

经编短切毡型双轴向设备的创新与应用

通过分析传统经编短切毡型双轴向设备生产过程中存在的坯布单位面积质量误差较大,坯布针孔大,坯布不美观,玻纤织物编织工艺单一,送经张力不稳定,复合针使用成本高等问题。研究设备对应存在的问题,并针对问题进行设备创新改造。     

Injection-molded plastic plate with hydrophobic surface by nanoperiodic structure applied in uniaxial direction

The purpose of this research is to establish a processing method for a wide-area nanometer scale periodic structure on the surface of a plastic plate in order to improve its hydrophobicity. We also evaluated the effect of a nanoperiodic structure applied in the uniaxial direction. Plastic plates of acrylonitrile–ethylene–styrene with dimensions of 100 × 100 mm² with a nanoperiodic structure on their surfaces were fabricated using a femtosecond laser and an injection molding technique. In the injection molding, the maximum transfer ratio for the depth reached as high as 0.79. When the nanoperiodic structure was applied in the uniaxial direction, the apparent contact angles did not decrease with respect to the direction of the ridges. As a result, the apparent contact angle increased by 20.4°, from 77.2° to 97.6° which is equivalent to 26%. In the six-month duration test, the sliding angle was initially decreased by applying the nanoperiodic structure. Additionally, the sliding angle was maintained between 20° and 38.3° during the duration test, which was lower than the angle for the flat plate at 42.7°. It can be considered that the depth was sufficient to maintain the sliding angle. In this condition, the contact angle hysteresis did not differ with or without the nanoperiodic structure on the surfaces, an effect that could be caused by surface dirt. In summary, the plastic plate was well drained and the characteristics were maintained for several months by forming the nanoperiodic structure on the surface.     

Experimental determination of laws of color harmony. Part 3: Harmony content of different hue pairs

At the Budapest University of Technology and Economics in 1956, we decided to start large‐scale experiments on color harmony. The experiments and the processing of the experimental data were completed in 2006. The experiments described in this article were based on a long established experience that harmony content of different hue pairs greatly differ from each other. The vast majority of former research activities on the subject of color harmony narrowed down mostly to investigations of saturated color pairs. Color samples of our experiments have been defined within the color space of the Coloroid color system, built on harmony thresholds. The compositions, prepared for the experiments, always consisted of two saturated hues and three low saturation colors of each hue at varying brightness, making it a total of eight colors. Within the framework of the experiments, 48 hues were used. Out of these, each of the 24 was formed into composition pairs with the remaining 48 hues, forming a total of 852 compositions. The paired‐comparison experiments were conducted with the use of the compositions prepared by collage technique. Color samples made of painted paper, between 1980 and 1985, have been repeated between 2002 and 2006 with the same color selection but with computer‐generated pseudorandom patch system compositions. It has been established that harmony content of hue pairs can be expressed by the relative angle of their hue planes in the Coloroid color space. The harmony content of hue pairs exceeds that of other pairs, when this angle is below 10°, between 30° and 40°, between 130° and 140° or near to 180°. Those color pairs of which hue planes are between 60° and 90° to each other in Coloroid color space, exhibit the least harmony content. © 2008 Wiley Periodicals, Inc. Col Res Appl, 34, 33–44, 2009.     

An experimental study of spouting in large sector beds

In a sector spouted bed, fluid is introduced into the bottom at the junction of two vertical walls, the bed forming a sector in horizontal cross-section. The hydrodynamics of beds of 30° sector angle have been studied in equipment of radius up to 0.78 m. The spout radius is greater than would be predicted from standard correlations on small circular beds. The overall pressure drop can be less than 20% of that found for minimum fluidisation. The vertical pressure distribution is given approximately by a quarter cosine function. Minimum spouting velocity decreases with increasing size of bed, loss of spouting being caused by a decrease in fountain height followed by snuffing of the spout by annular solids.     

光折变光子晶格局域光的角度要求研究

实验中我们用与在LiNbO_3:Fe晶体中写入光折变光子晶格时相同频率的光照射到LiNbO_3晶体写入光折变光子晶体的区域,在入射光与光折变光子晶格周期方向成较小的角度(小于12°)时,观察到了光折变光子晶格对光的局域现象。利用光在分层介质中传播时的传输特性,理论上计算了光在光折变光子晶格中传播时的反射率R与入射角度θ(入射光束与光子晶格周期方向的法线所成角度)之间的关系。发现理论计算结果与实验结果是相一致的。     

FDY8头纺改造为16头纺的工艺

探讨了利用东丽716型高速卷绕机8头纺的FDY设备改造成16头纺的工艺。通过提高丝束在GR2出口处的张力,避免丝束抖动碰撞及并丝。纸管尾丝槽的合理设计、卷绕角的合理调整,以及切换时卷绕张力的适当增加,保证了切换的成功率。而为了确保丝饼成型良好,卷绕角从切换时的5°很快降至并长时间保持在4.6°,卷绕张力不超过14cN。     

Improved-quality needles with a diamond-like coating (DLC) for stitching machines and their production technology

It has been shown that diamond-like coatings (DLCs) can be used to improve the service and consumer properties of steel stitching needles. The DLCs were found to give the greatest improvement of the service characteristics of the needles when the roughnesses of both the outer surface of the needle and the inner surface of the needle eye were small.     

Co-solvent-Modified Supercritical Carbon Dioxide Extraction of 10-Deacetylbaccatin III from Needles of Taxus baccata L

Abstract

10-Deacetylbaccatin III was extracted from the ground needles of Taxus baccata L. growing in Turkey using sub- and supercritical carbon dioxide with and without co-solvents by using two different methods (as an entrainer and modifier) and compared to Soxhlet extraction. SFE applications were carried out in the pressure range between 10 to 40 MPa and temperature ranges between 35 to 45°C. Recovery of the target compound increased with increasing temperature and pressure. The highest quantity of 10-deacetylbaccatin III obtained from needles of Taxus baccata L. was about 718 mg/kg when 200 µL of methanol was used as an entrainer at 45°C.     

Fabrication of regular arrays of organic crystalline needles using creases formed on oxidized poly(dimethylsiloxane) surfaces

In this study, creases are regularly self-assembled on the oxidized surface of poly(dimethylsiloxane) by swelling-induced buckling instability. These creases are then used as templates for the regular arrangement of crystalline needles. The solution of an organic compound is confined in the aligned creases and dried to generate a crystalline needle in each crease. Thus, the orientation of the crystalline needles and their two-dimensional position could be controlled. The organic compounds used in this study are anthraquinone and 9,10-dibromoanthracene, among which the latter is an organic semiconducting material. It is expected that the method proposed in the study can be used to fabricate regular arrays of organic semiconducting crystalline needles or nanowires that can be used as elements of electronic devices such as organic field-effect transistors and chemical sensors. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47736.     

The wettability of industrial surfaces: Contact angle measurements and thermodynamic analysis

The water wettability of surfaces, whose surface conditions are comparable to those used in heat and mass transfer equipment, has been investigated experimentally and theoretically.In the first part, results of contact angle measurements for water on metal and non-metal surfaces are reported. With hydrophobic non-metal surfaces (e.g. Teflon) water forms large advancing and receding contact angles, and the contact angle hysteresis is small. Surface contamination is of minor influence. Hydrophilic metal surfaces (copper, nickel) are completely wetted by water only if the surfaces are extremely clean. Surface contamination reduces the wettability drastically. Under most industrial conditions advancing contact angles between 40° and 80°, and receding contact angles smaller than 20° can be expected, and the contact angle hysteresis is large. Corrosion can enhance the water wettability.In the second part, a thermodynamic analysis of the wetting of heterogeneous surfaces is presented. Equilibrium considerations for a model surface consisting of two components of different wettability provide the advancing and receding contact angles for a heterogeneous surface as a function of the equilibrium contact angles, surface fractions, and the distribution function of the two components. The advancing and receding contact angles as well as all the intermediate contact angles indicate metastable states of equilibrium of the system. The results of the model calculations give a physically based explanation for the characteristic wetting behaviour of industrial surfaces found experimentally.