缠绕角对钢丝增强氟塑料软管组件应力水平的影响分析

运用有限元方法建立了钢丝增强氟塑料软管组件的参数化有限元模型,并运用该模型计算分析了钢丝缠绕角对软管组件应力水平的影响,得出了内管和增强钢丝的最大应力随缠绕角的变化规律。分析发现,内管的应力水平对缠绕角的变化极其敏感,钢丝缠绕角的轻微偏离会导致内管应力水平的大幅增加,因此在生产中须严格控制增强钢丝的缠绕角。     

工艺参数及使用条件对钢丝增强氟塑料软管组件应力水平的影响分析

运用有限元方法建立了钢丝增强氟塑料软管组件的参数化有限元模型,并应用该模型计算分析了工艺参数(内管厚度与增强钢丝缠绕角)和使用条件对软管组件应力水平的影响,得出了内管和增强钢丝的最大应力、应变随工艺参数和使用条件的变化规律,为该类软管的工艺参数优化、失效分析与预防提供了参考。     

影响高压钢丝缠绕液压软管接头总成性能的结构与工艺因素

分析了影响高压钢丝缠绕软管总成性能的因素,提出了扣压工序是影响总成质量的主要因素,并给出了设计软管总成的关键结构及有拳计算公式。     

缠绕张力对环缠绕复合材料气瓶应力的影响

提出了一种等效降温法,将缠绕张力产生的预应力等效模拟为复合材料层降温产生的预应力,通过理论推导得到了缠绕预应力与复合材料层降温量之间的计算公式,基于等效降温法并利用通用有限元软件研究了缠绕张力对环缠绕复合材料气瓶应力的影响。结果表明：随着缠绕预应力的增大,环缠绕复合材料气瓶内胆工作应力减小、复合材料层工作应力增大;缠绕张力预应力较大时会抵消自紧工艺效果,气瓶工作应力和纤维应力比主要受缠绕张力影响,在进行有限元应力分析和纤维应力比计算时应考虑缠绕张力作用。     

双折线式多层缠绕卷筒参数化建模与仿真分析

以太原重型机械集团有限公司1 300 t桥式起重机中的双折线式多层缠绕卷筒为研究对象,应用三维设计软件NX中草图、特征表达式等功能,实现双折线式多层缠绕卷筒及其螺旋线参数化建模。通过修改不同的参数值,快速实现折双折线式多层缠绕卷筒结构的自动更新。在参数化模型的基础上,结合多体动力学仿真程序Adams,建立起升钢丝绳模型,对双折线式多层缠绕卷筒钢丝绳缠绕过程进行动力学仿真,分析研究缠绕过程中钢丝绳缠绕及受力情况,校核验证双折线式多层缠绕卷筒的设计合理性,确保钢丝绳能够平稳缠绕到卷筒上,且受力均匀,为结构设计提供参考与依据。     

复合材料缠绕层缺陷深度对CNG-2气瓶强度影响的研究

通过创建一种特殊的模型路径叠加分析方法,利用有限元技术,研究和探讨了具有给定缺陷长度和不同缺陷深度的CNG-2气瓶的应力状态改变及状态叠加方法.通过重点研究不同缺陷深度对CNG-2气瓶内胆强度的影响,发现缠绕层缺陷深度变化对于缺陷局部附近的气瓶内胆强度和使用安全性有重要影响,而远离缺陷部位的内胆简体的性能几乎不受缠绕层缺陷深度的影响.     

SMA丝缠绕角对扭力驱动器驱动性能影响的试验研究

在智能结构的驱动系统研究中,形状记忆合金(SMA)以其独特的力学性能倍受关注。将含有预拉伸变形的SMA丝与薄壁圆管复合,能够构成具有扭转变形输出或转矩输出功能的驱动器,为飞行器翼面操纵系统等提供新的设计思路。在SMA扭力驱动器中,SMA丝的缠绕角是影响驱动器驱动能力的一个重要参数。针对缠绕角分别为40°、45°、55°、60°和75°的一组驱动器,采用试验手段,获得了自由状态、完全约束状态和弹性约束等三种状态下,上述驱动器的温度－缠绕角－扭转角(或转矩)等多组关系曲线,得到了当缠绕角为60°时,驱动器有最大扭转角和最大转矩的试验结果。研究结果对深入探索SMA扭力驱动器的力学模型和驱动器结构参数的优化具有重要的参考价值。     

并联机床整机组合设计的实现方法研究

并联机床整机组合设计是并联机床数字化快速开发平台的一个重要组成部分 ,其主要任务是实现从简单的运动学模型到具有实际意义的机床模型的过渡。本文提出了自动完成并联机床组合设计的替换方法 ,建立了一个相对完整的整机组合设计理论体系 ,并阐明了替换方法中替换基准的含义以及替换方法的局限性和应用时的注意事项     

应力水平对桥机金属结构优化及可靠性的影响

桥机金属结构优化设计的最优解往往把强度、刚度和稳定性的许用值用到极限,这样不能确保结构是否安全。引入了应力水平来定量的衡量桥机的设计裕度,用可靠度来衡量结构是否安全,分别采用不同的应力水平进行桥架的优化设计,然后通过蒙特卡洛法计算最优解的可靠度水平,获得了应力水平对桥机金属结构优化及可靠性的影响规律:桥机金属结构的重量随着应力水平的降低近似线性递增;结构的可靠度随着应力水平的降低不断提高,但提高的幅度越来越小,即提高设计裕度换取较高可靠度的回报率越来越低。     

Influence of tool steel properties on surface quality after electrical discharge machining by wire electrode

The International Journal of Advanced Manufacturing Technology - The paper describes the results of experimental research focused on the identification of the influence of properties of selected...     

The measurement of the axial internal stress in steel wire

Apparatus is described for the measurement of the approximate axial internal stress distribution in wires typically 0·3–0·4 mm diameter. A sensitive optical system measures the change of length of the wire as its diameter is reduced at a rate of about 0·3 μm per minute by dissolution in 0·012 M nitric acid maintained at a constant temperature. The change of area of cross section of the wire is deduced from measurement of its electrical resistance. The adoption of a continuous thinning process makes it possible to measure the internal stress at the original wire surface. The method is not able to take account of the effect on the axial strain of the relief of circumferential and radial stresses. This leads to the axial stress being underestimated by about 30%. Internal stress measurements are reported on patented and drawn steel wire which confirm the wide range of internal stress intensity that can be generated in this material by changing and drawing conditions.     

预应力钢绞线磁谐振应力监测试验研究

预应力钢绞线是混凝土结构的关键受力构件,其有效预应力一旦损失严重,将威胁结构安全。为了精准监测钢绞线应力状态,基于磁谐振原理和磁弹效应,提出预应力钢绞线磁谐振应力监测方法。设计了双线圈磁谐振传感器,分析了测试频率选择方法,搭建了钢绞线应力监测系统。为验证该方法的可行性,对不同设计拉力的镀锌钢绞线和涂环氧树脂钢绞线试件进行了应力监测试验。试验结果表明：不同批次的钢绞线对应的感应电压随拉力的变化趋势相似;感应电压和钢绞线应力非线性相关,三次拟合优度R~2均大于0.96,灵敏度可达0.064 79%/kN;依据拟合结果和测得感应电压计算钢绞线应力,得到在高荷载情况下钢绞线应力测试误差集中小于4%,为预应力钢绞线监测提供了新方法。     

Influence of impingement angle on solid particle erosion of carbon fabric reinforced polyetherimide composite

Polyetherimide (PEI) composite reinforced with plain weave carbon fabric (CF) (40% by volume) was developed and characterized for physical and mechanical properties. The erosive wear behaviour of PEI and its composite was evaluated using silica sand particles at a constant impact velocity but varying angles of impingement. It was confirmed that though all the mechanical properties of PEI improved substantially by CF reinforcement, the erosion resistance (W_R) deteriorated by a factor of almost four–six times at all angles of impingement. Both materials showed minimum wear at normal incidence (90° impingement). In spite of the fact that PEI is not a very ductile polymer (elongation to break-60%), it showed maximum wear at 15° which is a characteristic of ductile and semi-ductile mode of failure. The composite (elongation to break-1%) also showed highest wear at 30° (impingement at 15° was not studied). These phenomena were explained using scanning electron micrographs of the eroded surfaces.     

双幅板压制滑轮对钢丝绳疲劳寿命的影响

1引言 双幅板压制滑轮直接采用圆形钢板压制成带有二分之一绳槽形状的单片幅板,然后将2个单片幅板相对合拢,把胀管插入轮辐的预留孔,应用胀管铆接技术使幅板牢固地连成一体,再在轮缘绳槽部位装上工程塑料的绳槽衬。它是在注塑尼龙滑轮和轧制滑轮基础上发展起来的一种结构独特的新型滑轮。具有延长钢丝绳使用寿命、精度高和制造周期短等优点。     

Experimental and theoretical stress analysis of multi-mitred lined glass reinforced plastic pipe bends

Strain distributions in five right angled multi-mitred composite pipe bends have been measured while subjected to in-plane flexure, out-of-plane flexure and internal pressure, each type of loading being applied separately. Strains were restricted to the linear regime and were less than 0.2%. Each bend and associated straight tangent pipes consisted of a PVC lining wrapped with E-glass chopped strand mat layers impregnanted with polyester resin. Results were compared with theoretical estimates using existing conventional and finite element analyses. The pipes had a nominal inside diameter and an equivalent bend radius of 250 mm     

Effect of surface treatment on mechanical properties of glass fiber/stainless steel wire mesh reinforced epoxy hybrid composites

This paper investigates the effect of surface treatment for glass fiber, stainless steel wire mesh on tensile, flexural, inter-laminar shear and impact properties of glass fiber/stainless steel wire mesh reinforced epoxy hybrid composites. The glass fiber fabric is surface treated either by 1 N solution of sulfuric acid or 1 N solution of sodium hydroxide. The stainless steel wire mesh is also surface treated by either electro dissolution or sand blasting. The hybrid composites are fabricated using epoxy resin reinforced with glass fiber and fine stainless steel wire mesh by hand lay-up technique at room temperature. The hybrid composite consisting of acid treated glass fiber and sand blasted stainless steel wire mesh exhibits a good combination of tensile, flexural, inter-laminar shear and impact behavior in comparison with the composites made without any surface treatment. The fine morphological modifications made on the surface of the glass fiber and stainless steel wire mesh enhances the bonding between the resin and reinforcement which inturn improved the tensile, flexural, inter- laminar shear and impact properties.     

The erosion of carbon fibre reinforced plastic by repeated liquid impact

The erosion of unidirectional carbon fibre reinforced plastic by repeated impact with a liquid jet, has been studied at velocities of up to 90 m/s. The long fibre axis was in the plane of impact. The resistance to erosion is better for type 2 fibre composites than for type 1, but in absolute terms not particularly high; it is virtually independent of fibre volume loading and decreases very rapidly with increasing impact velocity. A certain number of impacts is needed before damage is observed. Then individual fibres are cracked and removed from the surface, and pits develop. It is suggested that failure is started by transverse compression fatigue of the fibres. The performance of composites in which the fibres are end-on to the water jet is better.