Investigation on the explosive welding mechanism of corrosion-resisting alu-minum and stainless steel tubes through finite element simulation and experi-ments

To solve the difficulty in the explosive welding of corrosion-resistant aluminum and stainless steel tubes, three technologies were proposed after investigating the forming mechanism through experiments. Then, a 3D finite element model was established for systematic simulations in the parameter determination. The results show that the transition-layer approach, the coaxial initial assembly of tubes with the top-center-point the detonation, and the systematic study by numerical modeling are the key technologies to make the explosive welding of LF6 aluminum alloy and 1Cr18Ni9Ti stainless steel tubes feasible. Numerical simulation shows that radial contraction and slope collision through continuous local plastic deformation are necessary for the good bonding of tubes. Stand-off distances between tubes (D1 and D2) and explosives amount (R) have effect on the plastic deformation, moving velocity, and bonding of tubes. D1 of 1 mm, D2 of 2 mm, and R of 2/3 are suitable for the explosive welding of LF6-L2-1Cr18Ni9Ti three-layer tubes. The plastic strain and moving velocity of the flyer tubes in-crease with the increase of stand-off distance. More explosives (R2/3) result in the asymmetrical distribution of plastic strain and non-bonding at the end of detonation on the tubes.     

半自动CO2气体保护焊在生产中的应用研究

针对手工电弧焊和气焊在焊接薄板时存在的诸多缺陷,介绍了半自动CO2气体保护焊技术及其特点,着重阐述了实际工程应用中半自动CO2气体保护焊电弧电压、电流极性、焊接回路电感、CO2气体量、焊丝中碳含量,以及焊丝直径和焊丝伸出长度等焊接参数的控制;阐述了合金元素的氧化现象、脱氧措施、焊接速度以及气孔控制等焊接工艺的控制技术,为提高薄板的焊接质量提供了重要参考.     

半自动CO2气体保护焊在生产中的应用研究

针对手工电弧焊和气焊在焊接薄板时存在的诸多缺陷,介绍了半自动CO2气体保护焊技术及其特点,着重阐述了实际工程应用中半自动CO2气体保护焊电弧电压、电流极性、焊接回路电感、CO2气体量、焊丝中碳含量,以及焊丝直径和焊丝伸出长度等焊接参数的控制;阐述了合金元素的氧化现象、脱氧措施、焊接速度以及气孔控制等焊接工艺的控制技术,为提高薄板的焊接质量提供了重要参考.     

高炉炉顶法兰裂纹修复工艺

工程当中很多金属材料都要求在焊接前、后对焊缝进行热处理,焊接热处理技术日益成熟的今天不断地在向智能化、自动化发展,但同样也是多样化的,我们需要对其进行深入的了解才能选择合适的技术手段,本文以某钢铁厂高炉炉顶法兰冷裂纹修复为例对焊接热处理技术的理解与总结。     

滚石冲击闭孔泡沫铝夹芯板耗能缓冲机理研究

在棚洞顶部铺设一定厚度砂土垫层可起到有效的耗能缓冲作用,不同厚度的砂土垫层耗能缓冲效果差异较大,如何量化砂土垫层厚度成为棚洞结构设计的关键问题之一。以实际棚洞结构为原型,采用动力有限元对滚石冲击砂土垫层进行数值仿真计算,分析不同冲击能量下多组砂土垫层厚度组合的动力响应及耗能缓冲机理。结果表明：低冲击能量下,改变砂土垫层厚度对滚石冲击力影响不大,而高冲击能量下,不同厚度砂土垫层的吸能减震效果有显著差异;增大砂土垫层厚度可有效的减弱滚石冲击对棚洞钢筋混凝土顶板造成的变形影响,但同时会增加结构自重,通过计算,可以得到最优化的垫层厚度,兼顾经济合理性和结构可靠性。研究成果将为滚石多发区棚洞结构砂土垫层的设计提供理论依据。     

彩钢岩棉夹芯屋面板、墙面板节点性能研究

为了掌握彩钢岩棉夹芯屋面板、墙面板与檩条的螺钉连接节点抗拉破坏机理,采用理论分析、试验验证及有限元模拟相结合的方法研究了不同钢板厚度及芯材厚度时节点破坏情况.分析结果表明:屋面板节点连接破坏是由于钢板局部屈曲引起的,墙面板则是钢板被冲剪破坏造成的,同时,结合对有限元模拟结果的回归,提出了节点承载力设计公式,可为以后节点设计提供参考.增加岩棉刚度及其与侧向钢板的粘结,或增加钢板厚度对提高屋面板节点极限承载力起着重要作用.     

Experimental investigation on vibration characteristics of sandwich beams with magnetorheological elastomers cores

A sandwich beam specimen was fabricated by treating with MR elastomers between two thin aluminum face-plates.Experiment was carried out to investigate the vibration responses of the sandwich beam with respect to the intensity of the magnetic field and excitation frequencies.The results show that the sandwich beams with MR elastomers cores have the capabilities of shifting natural frequencies and the vibration amplitudes decrease with the variation of the intensity of external magnetic field.     

Inconel718合金多层夹芯筒结构LBW/SPF技术研究

研究了超细晶Inconel718合金激光对接板高温塑性及多层夹芯筒结构的LBW/SPF成形技术。结果表明:垂直焊缝拉伸时最大延伸率发生在温度为950℃、应变速率为3.1×10-4s-1条件下,为400.6%,平行焊缝拉伸时最大延伸率发生在温度为965℃,应变速率为6.2×10-4s-1条件下,为164.0%。对接板在950～980℃相对胀形高度均高于1.0。通过设计直径可变的卡具以及采取点焊加固等措施,解决了多层夹芯结构的激光焊接难题。激光穿透焊参数:功率1 200 W,焊速1 200 mm/min,离焦量-1 mm,保护气体流量0.6 L/min,超塑成形参数:温度Tf=965℃,压力Pf=4.2 MPa,时间tf=130 min。采用LBW/SPF技术制造的多层夹心筒结构具有外观形状好、壁厚分布均匀、内部结构对称度高等优点。     

组合连接件对钢管-混凝土黏结性能的影响

为了揭示组合连接件对钢管与外围混凝土工作性能的影响规律,开展由环板、加劲板、焊钉组成的组合连接件对钢管与外围混凝土的黏结滑移性能影响试验研究.获取界面黏结-滑移曲线以及裂缝的分布规律,并在试验的基础上开展数值模拟参数分析,并与规范计算结果进行对比.研究结果表明：带组合连接件钢管特征滑移量大于6 mm,符合欧洲规范Eurocode-4对延性连接件的要求;环板与加劲板组合能更充分地利用混凝土的抗压性能,配置一定比率的焊钉能有效提升界面弹性抗滑移刚度;增大焊钉率可以提升界面塑性抗滑移刚度、极限抗滑移强度,高焊钉率的多排焊钉并未改变焊钉作为延性连接件的性质;单个焊钉实际极限荷载值与规范计算值基本一致.     

圆孔型蜂窝钢梁补强前后受力性能分析

蜂窝钢梁由于腹板的开孔削弱,使得剪力的作用效果越来越明显,严重降低了蜂窝钢梁的强度和刚度.现提出补强措施：在支座处添加大盖板,并利用ABAQUS有限元分析软件,对圆孔形蜂窝钢梁补强前后进行了有限元分析,将两种情况下的受力性能能进行了对比分析,得出结论.分析结果显示在支座处添加大盖板这种补强措施是非常有效的.为以后的设计提供了依据与合理化的建议.     

长持时爆炸冲击波产生方法

不同持时的爆炸冲击波对建筑结构及防护工程的作用显著不同,在试验或数值模拟中常需要得到长持时爆炸冲击波,延长爆炸冲击波正压作用时间是研究长持时爆炸荷载下结构响应的难点。在AUTODYN中建立长筒爆室小当量炸药多点延时起爆模型,分析爆炸冲击波在长筒爆室中的传播规律,研究管道长度、延时起爆时差、起爆顺序对冲击波波形的影响。结果表明：距离增加,超压峰值减小、正压持续时间增加;根据炸药量和爆室长度合理地选择起爆时差可以获得波形丰满且连续衰减的超压时程曲线;爆室底部起爆、合理控制延时间隔,可以形成类似于大当量远距离爆炸下产生的连续衰减的长持时冲击波。分别给出100、200 ms爆炸持时起爆方案,为长持时爆炸模拟装置的设计提供技术支持。     

Ly12 铝合金与 A3 钢爆炸焊接条件的确定

目的　确定 Ly1 2铝合金与 A3钢的爆炸焊接条件 .方法　针对 Ly1 2铝合金与 A3钢在直接结合的实验中出现的问题进行了详细的分析研究 ,提出了在 Ly1 2铝合金 (覆板 )和 A3钢 (基板 )之间插入中间材料 ( A3钢薄板 )的新的实验方法 .结果　通过实验确定出 Ly1 2铝合金与 A3钢爆炸焊接条件 .结论　插入中间材料后 ,能使 Ly1 2铝合金和 A3钢实现良好的焊接 .     

一种新型人工异向介质结构的设计和仿真

根据异向介质可以由具有等效负磁导率的开路环形谐振器阵列和具有等效负介电常数的细金属导线阵列构成的基本原理，提出了一种新型的、相互对等嵌入的开路环形谐振器的结构.与传统的开路环谐振器相比，新结构中内环和外环相互对称，具有更好的电流分布形态和电磁特性.采用这种新型开路环形谐振器阵列和细金属导线阵列组合，得到了一种新型的人工异向介质，并同时给出了完整的设计和仿真过程.通过对上述介质的功率传输特性和“负”Snell折射特性的仿真，表明该结构在特定的频段内表现出了明显的“异向”性质.     

New advances in fiber-reinforced composite honeycomb materials

In sandwich structures, lightweight cellular materials as the core hold the face sheets far away from the neutral axis to maximize the bending performance of the structure. Honeycomb materials as a major type of lightweight cellular materials have been widely applied in various fields, including aerospace, vehicle, marine, architecture and mechanical engineering, due to reliable mechanical properties and excellent designability. Using fiber-reinforced composites is an efficient method to develop ultralight honeycomb materials with superior mechanical behaviors. In recent years, fiber-reinforced composite honeycomb materials possessing lightweight and excellent mechanical performances have attracted noticeable attention to replacing traditional aluminum honeycombs and Nomex honeycombs. Compared to metal, polymer and Nomex paper, fiber-reinforced composites possess various merits, such as high specific stiffness and specific strength, excellent fatigue property, corrosion resistance and high-temperature resistance. Thus, the applications of fiber-reinforced honeycomb material for sandwich core have unlimited potential in hypersonic vehicles, long-range rockets, cargo vessels and protective systems. Although the fact that attention has been rapidly increasing, there is a lack of comprehensive reviews of new advances in the field of fiber-reinforced composite honeycomb materials. In this review, new advances reported by different scientists in the field of fiber-reinforced honeycomb materials have been reviewed and analyzed to provide an in-depth overview and knowledge for beginners in the field of ultralightweight and high-performance composite sandwich architectures. The challenges and prospects for the development of fiberreinforced honeycomb materials have also been presented.     

Research on Protection Capability of Flying-Whip Multifunctional Explosive Reactive Armor

The experimental research on protection capability of the flying-whip multifunctional explosive reactive armor (ERA) was performed, in which the comparison experiment was made on the damage effect of the flyingwhip‘s geometrical figuration, material property and driven velocity on the long-rod armor-piercing-projectile. The moving velocity of the flying-whip driven by different explosives and the pressure attenuation law of shock wave travelling in the back plate were measured respectively with the electric probe method and the manganin piezoresistive gauge technique. The following conclusions based on a great quantity of experimental data were drawn: compared with the sandwich ERA the flying-whip multifunctional ERA has very good protection function against the long-rod armor-piercing-projectile, the shaped charge warhead and the anti-armor tandem warhead. In addition, the composite plate made of the armor-steel and rubber plate can lessen the vibration and shock of the main armor caused by the explosion of the charge.     

夹芯梁结构分析的Fourier级数求解

夹芯梁具有重量轻，强度、刚度和稳定性好的优点．在现代复合材料结构中应用广泛．常用的夹芯结构分析理论有Ｒｅｉｓｓｎｅｒ理论和Ｈｏｆｆ理论．前者把表板视为薄膜求解．后者计及了表板自身弯曲刚度的影响，即把表板视为弹性薄板求解．Ｆｏｕｒｉｅｒ级数在匀质材料杆、板、壳经典理论中有重要应用．本文在此基础上．导出了Ｒｅｉｓｓｎｅｒ理论和Ｈｏｆｆ理论下的Ｆｏｕｒｉｅｒ级数求解通用方程。具有应用方便，能适用多种边界和复杂载荷作用夹芯梁分析的特点。     

起重机拼板不清根高效焊接及接头性能分析

为了解决拼板在焊接过程中的碳弧气刨清根、板材翻身导致焊接工序复杂、生产效率低下以及无法实行自动化焊接等问题,提出一种采用埋弧焊单面焊加陶瓷衬垫方法,板单元正面进行埋弧焊接,试板背面与陶瓷衬垫紧密贴合,从而实现拼板对接单面焊双面成形.研究结果表明,该埋弧焊接工艺满足100%RT和100%UT探伤,-20℃条件下冲击吸收功高于27 J,其力学性能结果符合标准要求.与传统工艺相比,该焊接工艺在保证其焊接质量的同时可简化生产工序,提高生产效率,降低生产成本,减少环境污染,实现绿色生产.     

金字塔点阵夹芯结构的精细优化设计

在本文中,为了提高金字塔点阵夹芯结构的整体等效剪切强度,提出了基于芯子和面芯界面性能协调的精细优化设计思想,并对面外剪切载荷作用下的金字塔点阵夹芯结构进行了优化设计.理论分析结果表明:基于精细优化设计思想的金字塔点阵夹芯结构中,由于综合考虑了芯子强度与面芯界面强度之间的性能协调,尽管会一定程度上降低了金字塔芯子的等效剪切刚度和等效剪切强度,但由于提高了面芯界面等效剪切强度,最终提高了夹芯结构的整体等效强度.     

圆筒环缝对接焊应力与变形的分析

利用桂壳理论的近似计算方法．对薄壁圆筒环向对接焊缝的应力与变形进行了分析讨论．定量地结出了焊后残余应力与变形随筒体尺寸及焊接条件而变化的规律．     

Zn-22Al泡沫夹芯复合板的三点弯曲性能

以Zn-22Al(ZA22)基泡沫材料为芯材,LY12铝板为面板制备了泡沫夹芯复合板。研究了泡沫夹芯复合板的三点弯曲行为,观察了复合板的破坏模式,分析了复合板弯曲性能的影响因素,运用层合梁刚度优化理论探讨了其机理。研究结果表明,ZA22泡沫夹芯复合板的三点弯曲载荷-位移曲线可按线性段、非线性段和失稳段表示其特征;其弯曲极限载荷随孔隙率的增大而减小,并且泡沫夹芯复合板表现出明显的层合效果。三点弯曲载荷作用下,泡沫夹芯复合板的主要失效模式为芯材的剪切破坏。