A METHOD FOR PREDICTING BUCKLING LOADS OF COMPOSITE LAMINATED STRIPS WITH A SURFACE NOTCH

Surface notches lower the stiffness of laminated strips, so they lower the buckling loads of the laminated strips, too. In this paper a new method is proposed to predict the buckling loads of the laminated strips with a surface notch. The theoretical and experimental results show that the buckling loads decrease as the depth or width of the surface notches increase; when the stacking sequence of the laminated strips is [0°/0°/+ θ/-θ/0°/0°/+θ/-θ] s , the buckling load decrease as θ increases. It proves that the method is reliable and significant.

Densification process of 10%B_4C-AA2024 matrix composite strips by semi-solid powder rolling

Semi-solid powder rolling（SSPR） is a novel strip manufacturing process,which includes the features of semi-solid rolling and powder rolling.In this work,densification process and deformation mechanisms of B4 C and AA2024 mixed powders in the presence of liquid phase were investigated.The relationships between relative densities and rolling forces were analyzed as well.The results show that liquid fraction plays an important role in the densification process which can be divided into three stages.Rolling deformation is the main densification mechanism in deformation area when the liquid fraction is lower than 20%.When the liquid fraction is equal to or higher than 20%,the flowing and filling of liquid phase are the densification mechanisms in deformation area.The relative densities increase with increasing rolling forces.The relative density–rolling force curves are similar at 550 °C and 585 °C.The characteristics of the curve shapes are apparently different at 605 °C and 625 °C.

Laboratory large-scale pullout investigation of a new reinforcement ofcomposite geosynthetic strip

In this paper,more than 70 large-scale pullout tests were performed to evaluate the performance of an innovative composite geosynthetic strip(CGS)reinforcement in sandy backfill.The CGS reinforcement is composed of a geosynthetic strip(GS)and parts of a scrap truck tire as transverse members.The experimental pullout results for the CGS reinforcement were compared with the suggested theoretical equations and ordinary reinforcements,including the GS,the steel strip(SS),and the steel strip with rib(SSR).The pullout test results show that adding three transverse members to the GS reinforcement(CGS3)with S/H?6.6(where S and H are the space and height of the transverse members,respectively)increases pullout resistance by more than 120%,170%,and 50%compared to the GS,the SS,and the SSR,respectively.This result shows that the CGS3(CGS with three transverse members)reinforcement needs at least 55.5%,63%,and 33.3%smaller length compared to the GS,the SS,and the SSR,respectively.In general,implementation of mechanically stabilized earth wall(MSEW)with the proposed strip may help geotechnical engineers prevent costly designs and solve the problem of MSEW implementation in cases where there are limitations of space.

EXPERIMENTAL STUDY ON DAMAGE TOLERANCE BEHAVIOUR OF COMPOSITE PANELS WITH SOFTENING STRIPS

In this paper an experimental study on damage tolerance behaviour of composite panels with softening strips is carried out. A prediction method of residual strength of panels with softening strips is proposed. The comparison between estimated and experimental results shows that the prediction method can be applied to design. In this paper the failure mechanisms are described.

DETECTION OF DELAMINATION IN A COMPOSITE PLATE BY SEM

A numerical method of integration of Green's functions of strip element method (SEM) is proposed The response of ultrasonic source generated by a transducer on the surface of a multi ply composite plate containing a delamination is analyzed by the use of SEM The numerical results show that the scanning features of the ultrasonic waves may be used to identify the delamination inside the composite plate.

MEASUREMENT OF INTERNAL STRESSES OF METAL MULTILAYER COMPOSITE COATINGS

The principle, formula and determination of internal stresses of metal multilayer composite coatings by means of the bending strip method were studied. Using this method, internal stresses of ion-plated metal multilayer composite coatings and thick monolayer coating of aluminium bronze, stainless steel and nickel-iron alloy were determined. The reason of decrement in internal stresses of multilayer composite coatings was discussed.

Graphene-gold Nanoparticle Composite Film Modified Electrode for Determination of Trace Mercury in Environmental Water

The graphene-gold nanoparticles composite film modified glassy carbon electrode （EG- AuNPs/GCE） was prepared by one-step coelectrodeposition and employed for determination of trace mercury in environmental water with differential pulse stripping voltammetry. Such a nanostructured composite film combined with the advantages of gold nanoparticles and graphene, can greatly promote the electron-transfer process and increase accumulation abil-ity for Hg（Ⅱ）, leading to a remarkably improved sensitivity. The linear calibration curve ranged from 0.2 μg/L to 30 μg/L for Hg（Ⅱ） and the detection limit （S/N=3） was found to be 0.03 μg/L at a deposition time of 300 s. Moreover, the stablity of the as-prepared electrode and interferences from other substances were evaluated. The modified electrode was successfully applied to the direct detection of Hg（Ⅱ） in real water samples.

冲击力下薄壁内衬复合管界面黏结强度效应分析

【目的】研究薄壁内衬复合管在受冲击力作用下的界面黏结强度对层间剥离屈曲的影响。【方法】建立薄壁内衬复合管在弹性阶段的非线性分析模型,对薄壁内衬复合管材模态试验与分析模型的分析结果进行对比,验证有限元分析模型可靠性。通过改变衬层与原基层管壁间的界面黏结强度,研究复合管在冲击力下的动态特征。【结果】研究结果表明,当冲击荷载较小、管道变形处于弹性阶段时,薄壁内衬复合管的损伤大都集中在层间界面处。界面黏结强度对层间剥离屈曲有较大的影响,随着层间界面黏结强度的增加,外基层管与内衬层的最大等效应力差值减少。此外,外基层管和内衬层的变形协调性能力随着黏结强度增加而增大,径向层间位移减小,增加了复合管的整体性和连续性。【结论】研究结果可为薄壁内衬修复管道设计方法及层间界面效应分析提供参考。

极端高温天气条件下不同鲜食玉米品种的种植表现

为科学选择适宜鲜食玉米/鲜食大豆带状复合种植的耐密、抗病、抗倒的鲜食玉米品种,为玉米大豆带状复合种植技术示范推广提供品种支撑,开展了11个鲜食玉米品种与鲜食大豆的带状复合种植试验。结果表明:在2022年夏季极端高温且持续时间较长的气候条件下,鲜食玉米/鲜食大豆带状复合种植模式下不同鲜食玉米品种在双穗率、空秆率等植株性状及千粒鲜重、出籽率、结实率等产量性状上差异明显,其中晶白甜糯、虞珑糯1612、苏玉糯5号、苏科糯1801、苏科糯1901这5个品种结实率较高,表现出较强的耐高温能力;苏甜糯818、斯达糯41、扬甜糯104结实率较低,表现出较低的耐高温能力。复种区各玉米品种鲜穗产量在7332~11440 kg/hm^(2)之间,除苏科糯1801、晶白甜糯较对照苏玉糯5号(CK)略增产外,其他各品种均较对照苏玉糯5号(CK)减产,减产幅度在1.53%~34.58%之间,以苏甜糯818、苏科糯1501减产最严重。清种区各玉米品种鲜穗产量在7638.89~14828.70 kg/hm^(2)之间,除苏科糯1801较对照苏玉糯5号(CK)略增产1.42%外,其他各品种均较对照苏玉糯5号(CK)减产,减产幅度在0.95%~47.75%之间,以苏科糯1501减产最严重。

不同醇化时间片烟原料化学成分特点与差异分析

烟叶醇化是去除烟叶青杂气、改善烟叶吸食品质的重要环节之一。为研究不同醇化时间对片烟常规化学成分含量及化学成分协调性的影响,本研究以醇化0、12、24、36个月的B3F片烟作为试验材料,将烟叶烘干打碎过筛后进行化学成分的测定,采用显著性方差分析研究不同醇化时间片烟原料质量成分及各种化学指标的比值之间的差异,从中选取最佳醇化时间的片烟,并筛选出关键醇化质量指标。结果表明:不同醇化时间的片烟原料成分之间存在差异,其中总氮、总植物碱、还原糖、总糖、钾含量存在差异,氯、淀粉含量不存在差异;随着时间的延长,总植物碱、总氮的含量先增加后减少再增加,还原糖、总糖的含量先减少后增加,钾含量逐渐增加,氯和淀粉含量变化幅度不大。总体而言,醇化12个月的片烟与醇化0、24、36个月的片烟的质量成分数值差异较大。另外,结合我国优质烟叶化学成分指标,就片烟原料化学质量特点来看,本研究中醇化时间24个月左右的烟叶品质最佳。

纯钛极薄带微流道刚柔复合模成形工艺

纯钛因存在延展性和各向异性导致成形性能差,难以成形高深宽比微流道。针对上述问题,提出了纯钛极薄带微流道刚柔复合模成形工艺,以提高纯钛极薄带成形性能,成形更大深宽比、壁厚更均匀的纯钛双极板微流道。通过单向拉伸实验测试了纯钛极薄带力学性能参数,采用刚柔复合模成形工艺研究了纯钛极薄带微流道成形极限,采用光学显微镜对微流道深度、深宽比和壁厚进行了测量分析。结果表明,纯钛极薄带存在显著的各向异性,TD方向r值最大为2.56,选择该方向垂直于微流道进行成形实验;在柔性垫厚度为0.35 mm时,微流道具有最大深宽比为0.53,较传统刚模微流道成形极限提高了26.7%,并显著提高了微流道壁厚分布均匀性。

BFRP条带-PVC管材复合加固纤维再生混凝土短柱轴压性能

为了研究BFRP条带-PVC管材复合加固纤维再生混凝土短柱的轴心抗压性能,对13组再生混凝土短柱进行了轴压试验和理论分析。主要研究变量为BFRP条带层数(0层、1层、3层)、BFRP间距(25 mm、37.5 mm和50 mm)和加固方式(无侧向约束、BFRP条带加固和BFRP条带-PVC管材复合加固)。研究结果表明:BFRP条带-PVC管复合加固不仅可以提高试件的极限承载力,还可以改善纤维再生混凝土短柱的破坏形态。在应力-应变曲线的非线性强化阶段,加固方式对试件刚度的影响更为显著。随着BFRP包裹量的增加,试件的峰值应力和极限应变均明显增加。依据试验数据建立的软化段的应力-应变计算模型具有较好的适用性。

Research on an innovative structure of an open-ribbed steel-ultra-high performance concrete composite bridge deck

To completely solve the problem of fatigue cracking issue of orthotropic steel bridge decks(OSDs),the authors proposed a steel–ultra-high performance concrete(UHPC)lightweight composite deck(LWCD)with closed ribs in 2010.Based on the successful application of that LWCD,an adaptation incorporating an innovative composite deck structure,i.e.,the hot-rolled section steel–UHPC composite deck with open ribs(SSD)is proposed in this paper,aiming to simplify the fabrication process as well as to reduce the cost of LWCD.Based on a long-span cable-stayed bridge,a design scheme is proposed and is compared with the conventional OSD scheme.Further,a finite element(FE)calculation is conducted to reflect both the global and local behavior of the SSD scheme,and it is found that the peaked stresses in the SSD components are less than the corresponding allowable values.A static test is performed for an SSD strip specimen to understand the anti-cracking behavior of the UHPC layer under negative bending moments.The static test results indicate that the UHPC layer exhibited a satisfactory tensile toughness,the UHPC tensile strength obtained from the test is 1.8 times the calculated stress by the FE model of the real bridge.In addition,the fatigue stresses of typical fatigue-prone details in the SSD are calculated and evaluated,and the influences of key design parameters on the fatigue performance of the SSD are analyzed.According to the fatigue results,the peaked stress ranges for all of the 10 fatigue-prone details are within the corresponding constant amplitude fatigue limits.Then a fatigue test is carried out for another SSD strip specimen to explore the fatigue behavior of the fillet weld between the longitudinal and transverse ribs.The specimen failed at the fillet weld after equivalent 47.5 million cycles of loading under the design fatigue stress range,indicating that the fatigue performance of the SSD could meet the fatigue design requirement.Theoretical calculations and experiments provide a basis for the promotion and application of this structure in bridge engineering.

Optimization of two-dimensional solid-state electrolyte-anode interface by integrating zinc into composite anode with dual-conductive phases

Solid-state electrolytes(SSEs)are a solution to safety issues related to flammable organic electrolytes for Li batteries.Insufficient contact between the anode and SSE results in high interface resistance,thus causing the batteries to exhibit high charging and discharging overpotentials.Recently,we reduced the overpotential of Li stripping and plating by introducing a high proportion of dual-conductive phases into a composite anode.The current study investigates the interface resistance and stability of a composite electrode modified with Zn and a lower proportion of dual-conductive phases.Zn-cation-adsorbed Prussian blue is synthesized as an intermediate component for a Zn-modified composite electrode(Li-FeZnNC).The Li-FeZnNC symmetric cell presents a lower interface resistance and overpotential compared with Li-FeNC(without Zn modification)and Li-symmetric cells.The Li-FeZnNC symmetric cell shows high electrochemical stability during Li stripping and plating at different current densities and high stability for 200 h.Full batteries with a Li-FeZnNC composite anode,garnet-type SSE,and LiFePO4 cathode show low charging and discharging overpotentials,a capacity of 152 mAh g^(−1),and high stability for 200 cycles.

多条银铜侧向复合带材的制备与性能研究

本文通过复合坯料结构设计优化以及在复合界面涂覆有机助剂,有效促进复合界面牢固结合,采用保护气氛烧结和冷轧联合工艺制备了Ag/Cu侧向复合带材,并对相关性能进行了测试分析。结果表明:Ag/Cu侧向复合带材银铜交替平行分布,不同银条宽度均匀,且在长度方向尺寸均匀性好,无腰鼓、腊肠等现象。复合界面呈犬牙交错的界面形貌,同时形成了30~50μm银铜两相共晶界面层,产生了冶金结合,界面结合牢固。复合界面剪切强度大于218 MPa,复合银条保持了高电导率,电导为58~60 MS/m。

直升机复合材料拉扭条扭转性能分析

拉扭条作为直升机旋翼桨毂的主要承力结构,承受桨叶旋转产生的离心力并通过自身的大变形实现桨叶的变距,其所承载的离心力和扭角变形随直升机飞行状态的变化而变化。针对复合材料拉扭条组件,基于ABAQUS建立仿真模型并求解应变和角度变形云图;设计静力试验台架进行验证试验来验证仿真模型,并进一步分析离心力、扭角对其扭转性能的影响。结果表明:复合材料拉扭条的扭转刚度随扭角的增大而减小,随离心力的增大而增大,且离心力对复合材料拉扭条的扭转刚度影响更大。

高性能AgPd50/806电刷材料工艺研究

针对高性能Ag Pd50/806电刷材料的工艺进行了深入研究,旨在提高其在微电机中的工作稳定性和使用寿命。研究首先分析了AgPd50/806合金的微观结构和力学性能,通过调控材料配方和增加固溶时效处理来改善工艺,实现了合金内部结构的均匀性和致密性,显著提升了材料的硬度、回弹位移量(1400μm)及抗拉强度(735 N/mm^(2))和延伸率(4.75%)。测试结果表明,优化后的Ag Pd50/806电刷材料在高温、高湿和振动等恶劣条件下表现出优异的可靠性和耐磨性,工作寿命长达290 h以上,其电接触性能和机械性能优于大多用传统工艺和其他合金制备的电刷材料。

怀远县淝河镇玉米-大豆带状复合种植技术要点

从良种选择、种子处理、整地、施肥、除草、病虫害综合防治等方面对怀远县淝河镇玉米-大豆带状复合种植技术进行了总结。收获后进行考种,玉米-大豆带状复合种植,平均收获玉米5700 kg/hm^(2)、大豆2100 kg/hm^(2),总收益28560元/hm^(2),不仅解决了争地问题,促进了粮食安全,而且改善了生态环境,增加了农户收入。

复合材料帽形加筋壁板加捻区质量问题研究

帽形加筋壁板结构的复合材料制件具有比强度高、比刚度高、可设计性良好等优点,在航空航天等工程领域得到了广泛的应用,而加筋结构的三角空隙必须使用捻条进行填充。采用“湿长桁+湿蒙皮”共固化工艺制造帽形加筋壁板复合材料制件时,发现捻条的外形会显著影响制件的成型质量。为了提高帽形加筋壁板制件的成型质量,研究了不同材质的长桁芯模、捻条制备方法、捻条填充量对加捻区长桁及蒙皮质量的影响。结果表明:由专用的加捻模具制备并在(60±5)℃的温度下预压实后,捻条预成型体的外形更精确,与其他结构配合更好;当捻条的填充量修正系数为1.1时,可有效避免蒙皮和长桁出现纤维褶皱;所选用的硅橡胶芯模固化成型后加捻区质量控制更好。

大豆-玉米带状复合种植株行距优化

合理的株行距配置可使大豆-玉米带状复合种植增产增收。为明确适宜界首市推广的大豆-玉米带状复合种植株行距,文章采用6∶4(大豆∶玉米)种植模式,研究4种不同株行距配置对大豆-玉米带状复合种植产量和产值的影响。结果表明,在大豆∶玉米6∶4种植模式下,品种组合1、2、3适宜株行距配置为大豆∶12 cm×30 cm,玉米∶12 cm×60 cm;品种组合4、5适宜株行距配置为大豆∶12 cm×30 cm,玉米∶14 cm×50 cm。在此株行距配置下,各品种组合的产量及产值最高,适宜在界首市推广应用。