Minimum weight design of helically and hoop wound toroidal hydrogen storage tanks with variable slippage coefficients

This article determines the optimal winding parameters for helically and hoop overwound toroidal hydrogen storage tanks, based on the application of variable slippage coefficients. First, an optimality condition between helical winding angle and hoop‐to‐helical thickness ratio is derived from the minimum strain energy density criterion. The winding angle distributions are then obtained with the aid of the optimality condition, taking into account the shell thickness variation along the meridional direction. The general criteria for fiber trajectory stability on a torus are presented, and the relationship for the slippage coefficient and the helical winding angle is formulated according to the windability and manufacturability. The helical winding angle and thickness at the equator are considered as design variables, whereas the minimum weight acts as the objective function. A design example with a toroidal hydrogen storage tank is outlined to demonstrate the favorable performance of the present method. The results show that the present method using variable slippage coefficients leads to a better distribution of the fiber stress in the toroidal shell and an efficient utilization of the laminate strength. The obtained winding parameters can thus be regarded as optimal for filament‐wound toroidal hydrogen storage tanks. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers     

纤维缠绕复合材料压力容器CAD/CAE/CAM一体化研究

本文用APDL参数设计语言编制的程序可同时进行压力容器缠绕过程的动态仿真模拟及应力分析,可将实际缠绕参数直接用于应力分析,分析后得到的仿真数据可直接用于数控缠绕机进行生产,实现了纤维缠绕复合材料压力容器CAD/CAE/CAM一体化.本文用微分几何理论推导出纤维缠绕复合材料压力容器的非测地线缠绕轨迹、包角方程及绕丝头运动方程.在应力分析过程中考虑了几何非线性和物理非线性.采用叠层的增量本构关系,以分段线性表示单层非线性应力-应变曲线,对损伤后引起的刚度降低进行了实验研究,实验特别研究了面内剪切破坏和层间剪切破坏对纵向弯曲刚度的影响.结果表明纤维缠绕复合材料压力容器损伤后,弯曲刚度的降低是影响轴向变形的重要因素.     

复合材料球形气瓶非测地线缠绕线型设计和强度分析

碳纤维复合材料球形气瓶因其较高的比强度、比刚度和抗疲劳性,被广泛应用于航空航天及民用工业领域。基于微分几何理论,推导出满足球形气瓶缠绕基本原理的落纱点轨迹方程,给出缠绕线型轨迹和缠绕角应该满足的稳定缠绕条件,并对缠绕轨迹进行仿真。考虑球壳的变曲率特点,针对球形气瓶缠绕层进行变厚度、变角度的精细化有限元建模,对工作压力下的气瓶内衬和缠绕层各向应力分布进行数值模拟和分析,并预测了气瓶的爆破压强。结果表明,优化设计得到的缠绕线型参数既能满足缠绕工艺的基本要求,又有效提高了球形气瓶的结构力学性能。研究成果对复合材料球形压力容器的设计制造具有重要的意义。     

球型封头压力容器的结构层次设计及缠绕成型工艺的研究

通过对实际球型封头压力容器产品的研制,阐述了球型封头压力容器结构层次的设计方法,介绍了在缠绕成型工艺中出现的问题及解决方法。     

不等极孔压力容器缠绕线型的理论分析与计算

对在压力容器缠绕成型中,同一个纵向缠绕层中两端封头采用不同的缠绕角缠绕进行缠绕线形的理论分析与计算。     

FWRP压力容器的可靠性设计研究

纤维缠绕聚合物基复合材料(FWRP)压力容器在航空航天及民用领域的应用是当前研究热点。减轻结构重量对于性能和成本都具有非常重要意义。为实现FWRP压力容器结构设计和安全评定的高目标,引入可靠性理论,应用统计学原理,基于应力-强度干涉模型,以同一失效概率为标准进行FWRP压力容器结构设计,以取代现应用的传统安全系数法设计。采用无碱无捻玻璃纤维-环氧树脂材料体系,应用同一缠绕工艺制备8个压力容器。试验得到纤维强度、缠绕角、几何尺寸、爆破压力等随机变量特征值。其结构可靠性设计值(纤维缠绕壁厚)与试验结果基本吻合,并显著小于常规设计值。将各设计变量随机分布特征值与压力容器结构设计相结合,实现安全与经济的有效统一,为可靠性设计在FWRP压力容器上的应用与发展提供了依据。     

固体发动机纤维缠绕壳体的成型工艺设计及试验

采用网格理论对缠绕壳体进行了工艺参数的设计计算,计算出缠绕工艺参数,结合微机控制缠绕软件编制程序,提出了强度设计、线型控制、变形校核三位一体的设计思想,确定了缠绕工艺设计的内容、计算方法及所需和所应产生的参数结构,对包络线轨迹进行平滑处理,控制缠绕线型,用实验进行壳体筒身段的强度设计和变形(强度)校核,结果表明理论分析与实验结果能够较好地相互吻合,壳体的爆破压强误差较小,其值小于5%.     

Transient Simulation of Hollow‐Fiber Membrane Filtration with Nonuniform Permeability Distribution

Transient simulation of filtration in hollow‐fiber membranes with nonuniform permeability distribution was conducted. The diversity of permeability distributions caused different initial flux and transmembrane pressure distributions. Manipulating the permeability distribution enables a hollow‐fiber membrane to achieve its maximum volumetric flow rate. During solid‐liquid separation, the inter‐adjustment between flux and cake distributions improved their uniformities simultaneously. The reciprocal of the volumetric flow rate of the membranes all increased linearly with water production. Severely nonuniform permeability distribution caused low water production. The numerical results could be applicable to account for the non‐ideal performance of industrial hollow‐fiber membrane modules.     

封头缠绕技术改进新策略

描述了带封头容器纤维缠绕排线的不对称现象，找出形成原因及防止办法。     

纤维缠绕环形压力容器复合材料结构设计

本文在环形容器复合材料缠绕原理的基础上,从环形容器工作下的受力状态分析入手,推导出环形容器的受力方程;根据环形容器双螺旋缠绕测地线方程,结合相关工艺参数,进行复合材料结构铺层设计,确定出优化缠绕线型的切点数。根据该理论,通过编写VB程序,实现纤维缠绕环形容器复合材料纤维层的计算机参数化设计。     

ANALYSIS OF A GEODESIC DOME SOLAR FRUIT DRYER

This paper analyzes use of geodesic domes as low cost and practical solar energy drying systems, especially for developing countries. A geodesic dome solar fruit dryer was designed, constructed and tested for drying grapes. The structure was constructed using wooden members, covered with transparent tedlar plastic and a black absorber inner shell. Fresh air is heated in the space between the outer shell and the absorber sheet. The hot air then passes through the fruits on the trays and exits from the top. The dryer was tested for drying grapes under two different modes, namely natural convection and forced air flow. In addition, theoretical results were obtained by thermal-electrical simulation and considering the heat and mass transfer phenomena between the air and the grapes.     

ANALYSIS OF A GEODESIC DOME SOLAR FRUIT DRYER

This paper analyzes use of geodesic domes as low cost and practical solar energy drying systems, especially for developing countries. A geodesic dome solar fruit dryer was designed, constructed and tested for drying grapes. The structure was constructed using wooden members, covered with transparent tedlar plastic and a black absorber inner shell. Fresh air is heated in the space between the outer shell and the absorber sheet. The hot air then passes through the fruits on the trays and exits from the top. The dryer was tested for drying grapes under two different modes, namely natural convection and forced air flow. In addition, theoretical results were obtained by thermal-electrical simulation and considering the heat and mass transfer phenomena between the air and the grapes.     

方形截面纤维表面气溶胶粒子多机理过滤性能数值分析

采用数值方法求解绕方形截面纤维流场,考虑粒子布朗扩散、拦截效应和惯性碰撞捕集机理的联合作用,用布朗动力学方法研究方形截面纤维的过滤性能,考察了纤维迎风角(θ)、填充率(C)和过滤风速(u?)对捕集效率、质量因子及粒子沉积分布的影响。结果表明,小粒子的扩散捕集或大粒子的惯性捕集在方形纤维表面的粒子沉积行为均表现出显著的局部沉积特征,且与粒子捕集机理和迎风角有关。方形纤维质量因子的分析结果表明,在高填充率下,方形纤维的过滤压降虽高于圆截面纤维,但具有较高的捕集效率,综合过滤性能仍明显优于圆截面纤维,但在低填充率下,方形纤维综合过滤性能劣于圆截面纤维。     

基于非测地线理论五坐标缠绕的实验研究

本文分析了4坐标缠绕对纤维缠绕构件机械性能和质量的影响,提出摆角坐标B轴的意义,并针对椭球压力容器这种典型的回转体芯模,研究了具体的各坐标机器路径。为了解决4坐标纤维缠绕过程中纤维在封头处的扭曲、堆积现象,进行了5坐标纤维缠绕实验研究。通过4坐标和5坐标的一个标准缠绕线型,分析和对比纱线的变化情况。实验表明,5坐标缠绕较好地解决了封头处纤维堆积问题。     

纤维缠绕压力容器最佳预应力与缠绕张力关系研究

为提高纤维缠绕压力容器的结构效率,对压力容器纤维缠绕预应力及其内衬形式之间的关系进行了研究,应用压力容器设计的弹性及半弹性分析方法,推导出纤维缠绕张力及其界面最佳预应力之间关系的表达式。     

Preparation of poly(lactic acid) fiber by dry–jet–wet spinning. II. Effect of process parameters on fiber properties

The dry–jet–wet spinning process was employed to spin poly(lactic acid)(PLA) fiber by the phase inversion technique using chloroform and methanol as solvent and nonsolvent, respectively, for PLA. The as spun fiber was subjected to two‐stage hot drawing to study the effect of various process parameters, such as take‐up speed, drawing temperature, and heat‐setting temperature on the fiber structural properties. The take‐up speed had a pronounced influence on the maximum draw ratio of the fiber. The optimum drawing temperature was observed to be 90°C to get a fiber with the tenacity of 0.6 GPa for the draw ratio of 8. The heat‐setting temperature had a pronounced effect on fiber properties. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3774–3780, 2006     

Stochastic simulation of the influence of fibre path variability on the formation of residual stress and shape distortion

A stochastic cure simulation approach is developed and implemented to investigate the influence of fibre misalignment on cure. Image analysis is used to characterize fiber misalignment in a carbon non‐crimp fabric. It is found that variability in tow orientation is significant with a standard deviation of 1.2°. The autocorrelation structure is modeled using the Ornstein‐Uhlenbeck sheet and the stochastic problem is addressed by coupling a finite element model of cure with a Monte Carlo scheme. Simulation of the cure of an angle shaped carbon fiber‐epoxy component shows that fiber misalignment can cause considerable variability in the process outcome with a coefficient of variation in maximum residual stress up to approximately 2% (standard deviation of 1 MPa) and qualitative and quantitative variations in final distortion of the cured part with the standard deviation in twist and corner angle reaching values of 0.4° and 0.05° respectively. POLYM. COMPOS., 38:2642–2652, 2017. © 2015 The Authors Polymer Composites published by Wiley Periodicals, Inc. on behalf of Society of Plastics Engineers     

玻璃钢弯管缠绕机的设计

设计了一种玻璃钢弯管缠绕机。弯管模往复摆动 ,供料系统的吐丝头绕管模旋转 ,形成缠绕运动。该机基本实现了测地环形缠绕和管壁厚度均匀     

玻璃纤维缠绕容器的水压应变测试及分析

简要介绍了直径0．50m的球形及柱形玻璃纤维缠绕压力容器的结构设计；试验研究了在1、2、3、4、5、6和OMPa水压试验条件下，2个球形及2个柱形容器外表面有代表性的7个和9个测点的压力应变；结果表明带金属内衬的纤维缠绕压力容器制造工艺稳定，在6MPa水压时承力纤维的最大应变还不到其极限应变的1／20，说明这类容器的承压潜力巨大。