纤维缠绕复合材料气瓶内衬的屈曲分析

为深入了解纤维缠绕复合材料气瓶的内衬屈曲情况,基于ANSYS有限元软件,运用数值模拟方法对纤维缠绕复合材料气瓶的金属内衬结构进行屈曲分析,建立了复合气瓶内衬结构的有限元模型,采用特征值法分析得出内衬1~10阶的屈曲模态,并利用非线性稳定法绘出内衬位移量随外压变化曲线.结果表明,计算得到的内衬临界失稳外压为0.199 MPa,与复合气瓶内衬外压试验结果相符合,证实了本文对于复合气瓶内衬屈曲分析的可靠性.     

超薄金属内衬复合材料压力容器的结构分析

采用有限元方法对超薄金属内衬复合材料压力容器结构进行分析。在分析中, 几何模型中的封头段考虑了复合材料铺放角度和厚度沿平行圆半径变化, 材料模型中的复合材料层和内衬层分别选用复合材料层合板理论和弹塑性理论进行分析, 二者之间的界面变形协调性及不可贯入性引入接触分析进行考虑。数值结果表明:在工作压力下, 容器复合材料层纵向应变均为拉应变, 环向存在部分压应变, 内衬层发生塑性变形; 卸载后, 容器的复合材料层处在拉应力状态, 内衬层处在压应力状态。在此基础上, 利用容器的简化模型, 根据内衬层最大变形点荷载位移曲线实现了容器内衬层局部屈曲模拟。容器水压应变测试和内衬局部屈曲观测结果与数值模拟结果吻合较好, 验证了本文中分析的可靠性。      

钛内衬复合材料环形气瓶结构设计与优化EI北大核心CSCD

根据微分几何,推导环形气瓶测地线缠绕轨迹以及缠绕角应满足的稳定缠绕条件,并针对不同切点数进行线型轨迹仿真。基于有限元分析,针对钛合金内衬环形气瓶的初始缠绕角及缠绕层数进行优化设计,并评估对比有、无环向补强层的环形气瓶承载能力。结果表明:本文设计的测地线轨迹精确可靠,很好地满足环形气瓶的缠绕工艺性。优化设计的缠绕参数既满足工艺可缠性,又能提高环形气瓶的结构性能。此外,有环向补强层的气瓶爆破强度提高了14%,钛合金内衬屈服强度提高了24.8%。因此,采用环向补强层有利于进一步提高环形气瓶的承载性能。水压实验结果表明本文设计方法预测的变形和爆破压力与实验值吻合良好。     

专利技术

正一种碳纤维复合材料高压气瓶申请(专利)号:201310282249.1公开(公告)日:2014-01-08申请(专利权)人:江苏久维压力容器制造有限公司摘要:本发明公开了一种碳纤维复合材料高压气瓶,包括金属内衬,以及依次设在金属内衬外表面的缠绕碳纤维复合层和外保护层;其中,所述缠绕碳纤维复合层的制备过程为:将环氧树脂和固化剂混合得到胶状溶液,并在该胶状溶液中加入短切碳纤维得到环氧树脂浸渍液,然后将连续碳纤维经过环氧树脂浸渍液浸渍后,在金属内衬外表面进行     

内衬聚偏氟乙烯热塑层的纤维缠绕复合材料管径向平压性能

纤维缠绕角度、纤维缠绕层厚度及碳/玻纤维混杂比是影响内衬聚偏氟乙烯(PVDF)热塑层的纤维增强热固性复合材料缠绕管径向平压性能的重要因素,其性能直接决定复合材料缠绕管产品掩埋深度和抗碾压能力。将PVDF颗粒经挤出机制成PVDF管,然后以表面喷砂处理后的PVDF管为内衬芯管,采用湿法缠绕技术制备不同结构参数的复合材料缠绕管。利用管平行板外载平压性能测试方法,测试了3种结构参数对复合材料管径向平压性能的影响,并分析其破坏模式与失效机理。结果表明,随缠绕层厚度的增加,径向压缩强度和径向压缩模量逐渐增大;随着缠绕角度的增大,径向压缩强度和径向压缩模量先增大后减小;另外,随着碳/玻纤维混杂比的提高,复合材料缠绕管的压缩强度和压缩模量相应增加。     

专利技术

一种轻金属内衬玄武岩纤维全缠绕复合气瓶及其制造工艺,包括：一轻金属内衬;复合有环氧树脂材料的玄武岩纤维缠绕层,该玄武岩纤维缠绕层形成于所述轻金属内衬外表面上,且通过该玄武岩纤维缠绕层中的环氧树脂材料使其与轻金属内衬紧密地粘结成一体;以及涂覆于所述玄武岩纤维缠绕层外表面的保护胶层。本复合气瓶满足合理的应力场分布,保证复合气瓶在使用最小的纤维用量条件下能承受最大的爆破压力,具有持久的良好气密性能和最佳的安全性能。     

缠绕图型对纤维缠绕复合材料力学性能影响的有限元模拟

针对纤维缠绕复合材料结构中存在纤维束交叉起伏和铺层走向交替的特点,建立了一种分析缠绕图型对缠绕复合材料结构力学性能影响的有限元方法。采用ABAQUS有限元软件,分析了考虑纤维束交叉起伏和铺层走向交替后缠绕复合材料圆柱壳的应力、应变分布规律,并且研究了缠绕图型对缠绕圆柱壳屈曲临界载荷的影响。结果表明:采用层合板模型计算得到的圆柱壳的应力分布比较均匀;考虑纤维束交叉起伏和铺层走向交替后,缠绕复合材料圆柱壳的应力不再均匀分布,应力云图出现规则分布的菱形图案,在菱形区域中纤维交叉起伏和铺层走向交替处的应力有明显的波动。本实验有限元模型中的菱形特征单元可以反映缠绕复合材料纤维交叉起伏和铺层走向交替的实际情况。     

缠绕图型对纤维缠绕复合材料力学性能影响的有限元模拟

针对纤维缠绕复合材料结构中存在纤维束交叉起伏和铺层走向交替的特点,建立了一种分析缠绕图型对缠绕复合材料结构力学性能影响的有限元方法。采用ABAQUS有限元软件,分析了考虑纤维束交叉起伏和铺层走向交替后缠绕复合材料圆柱壳的应力、应变分布规律,并且研究了缠绕图型对缠绕圆柱壳屈曲临界载荷的影响。结果表明:采用层合板模型计算得到的圆柱壳的应力分布比较均匀;考虑纤维束交叉起伏和铺层走向交替后,缠绕复合材料圆柱壳的应力不再均匀分布,应力云图出现规则分布的菱形图案,在菱形区域中纤维交叉起伏和铺层走向交替处的应力有明显的波动。本实验有限元模型中的菱形特征单元可以反映缠绕复合材料纤维交叉起伏和铺层走向交替的实际情况。     

纤维缠绕复合材料固化过程残余应力/应变的三维数值模拟

采用有限元分析软件ABAQUS,对具有金属内衬的纤维缠绕复合材料圆筒在固化过程中残余应力及应变的变化规律进行了模拟计算。采用FORTRAN语言编制了用以分析固化过程中残余应力的子程序,该子程序考虑了固化过程中复合材料力学性质的变化和由于树脂固化收缩产生的化学收缩应变。算例结果表明：复合材料和金属内衬的残余应力在初始阶段均接近于零,当固化到一定阶段,残余应力迅速增加并且很快达到最大值,在降温阶段释放了部分的残余应力;在整个固化过程中,金属内衬受到压应力,而纤维缠绕层受到拉应力。本文中的三维有限元模型可以得到任意时刻复合材料的温度及固化度分布,通过数值模拟可以有效地优化复合材料固化工艺参数,提高制件的质量。     

具有金属内衬复合材料纤维缠绕容器固化过程的数值模拟

基于固化反应动力学、热传导和复合材料层合理论, 采用了有限元分析方法, 对具有金属内衬的复合材料纤维缠绕压力容器在固化工艺过程中的温度和热应力分布及其变化规律进行了数值模拟。通过一典型容器数值分析, 表明在固化工艺过程中, 中容器内部的所有应力分量具有同时达到峰值的特征, 其中应力分量的峰值出现在固化降温阶段的初期。提出了数值模拟的方法和分析结论对复合材料结构设计师和工艺师合理制订金属内衬复合材料纤维缠绕容器的工艺标准具有一定的参考价值。      

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

From Industry 4.0 to Research 4.0. Development of High Performance Fibers in the Light of Digitization

We associate a variety of innovations with the term ＂Industry 4.0＂. The pioneer of many 4.0 modifications forms the basisfor the trend towards the integrated di...     

Flow calorimeter for enthalpy increment measurements on condensed gases

A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.     

Refrigerators Enter a New Era of Health Preservation Frestech initiates the establishment of China's first standard for household sterilization refrigerators

On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……     

Roman iron and steel: A review

ABSTRACT

The production of ferrous metal increased during the Roman Late Republican period, Principate and Empire. The direct bloomery process was used to extract the metal from its ores using slag-tapping and slag-pit furnaces. The fuel was charcoal and an air blast was introduced by bellows-operated tuyères. Iron formed as a bloom, often as a spongy mass of metal, which contained impurities from the smelting process, including unreacted ore, fuel, slag and fragments from the furnace walls, while the metal was often inhomogeneous with varied carbon contents. Blooms were either smithed directly into bars or ingots or they were broken up, which also allowed the removal of gross impurities and a selection of pieces with similar properties to be made. These could then be forge-welded together and formed into characteristically shaped ingots. Making steel in the furnace seems to have been achieved: it depended on the ore and the furnace and conditions within it. Surface carburization was also carried out. Iron and steel were used extensively in construction and for tools and weapons. Fire welding was often used to add pieces of steel to make the edges of tools and weapons, which could be heat-treated by quenching to harden them.     

Optimum-Simulation von Ernteprozessen

Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß.     

A study of centrifugal cast high boron high speed steel

In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M₂(B,C), (W,Mo)₂(B,C), M₃(B,C), M₂₃(B,C)₆ type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm². The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K₁ mill housing of bar mill.     

Synthesis of Alumina-Zirconia Nanocomposites by Solgel Process

Al₂O₃-ZrO₂ nanocomposites were developed starting with the solgel process. Composite alumina-zirconia nanopowders were synthesized from metallorganic precursors (Aluminium secondary butoxide and zirconium Iso propoxide) using the solgel process. The parameters affecting the synthesis—solvent, concentration of precursor, R/H ratio (i.e., dilution of water in solvent)—were varied as also the temperature and pH. BET and TEM were used to measure nanosize. Diffuse reflectance spectroscopy and also qualitative optical absorption led to identical particle size estimate. The variation of process parameters was used to study the effect and interdependence of process parameters. Artificial Neural Networks was used to rigorously analyze the process. Although this led to confirmation of interdependence of parameters, the presence of a single overwhelming solvent variable was also established. Then the optimal process was used to synthesize more nanopowder. To produce bulk nanocomposite the nanopowders were sintered by varying the temperature and time period. The sintered lithoids were probed with a vickers hardness tester to measure elastic modulus, hardness, and fracture toughness. The results showed high elastic modulus, modest hardness, and very high fracture toughness.