钢丝缠绕增强塑料复合管强度分析与优化设计

【作者】 林秀锋；

【导师】 郑津洋；

【作者基本信息】 浙江大学 ， 化工过程机械， 2006， 硕士

【摘要】 钢丝缠绕增强塑料复合管(以下简称PSP管)是一种性能优良的新型复合管。它以高强度钢丝左右螺旋缠绕成型的网状骨架为增强体,以高密度聚乙烯为基体,并用高性能的粘结树脂层将钢丝网骨架与内外层高密度聚乙烯紧密地连接在一起。这种独特的结构不仅使PSP管集钢管的高强度与塑料管的耐腐蚀性两种优点于一体,还克服了金属板骨架增强塑料复合管易脱层等缺陷。PSP管生产效率高,综合性能优越,具有广阔的应用前景。 目前,对PSP管的研究大多停留在生产、安装及应用等方面,对其强度分析及优化设计的研究尚未见文献报导。本文首次对其力学性能展开系统的理论研究,通过建立PSP管力学模型,分析PSP管的强度及其失效形式,并在此基础上对PSP管进行结构优化设计。本文所作的主要工作如下: (1)建立PSP管力学模型,计算其相应的弹性常数。将PSP管简化为内层、复合层、外层三层结构组成的力学模型,其中复合层由上下两层单层板组成;参考回形模型、串并联模型以及Halpin-Tsai经验公式计算得到单层板弹性常数;采用P.C.Chou多层板宏观模量分析方法计算得到复合层弹性常数;并对PSP管整体弹性特性进行研究。结果表明,通过钢丝缠绕增强,PSP管环向刚度有较大提高,而其轴向刚度相对提高较小。 (2)PSP管在不同载荷作用下的应力分析和抗外压性能分析。分别采用三层模型和整体模型对在内压作用下的PSP管弹性阶段进行应力分析;通过割线模量法分析材料塑性对管材性能的影响,得到PSP管弹塑性内压-应变曲线,揭示了管材从弹性变形到塑性变形的全过程,与实验值对比发现所进行的应力分析能较好地预测PSP管的变形情况。分析弯矩对管材的影响,讨论了内压与弯矩联合作用下PSP管的应力应变。研究PSP管的抗外压性能,给出了PSP管外压失稳的临界压力计算式,计算值与试验值对比表明,所得公式能较好地预测其失稳压力,说明所建模型及有关分析是合理的。 (3)PSP管常温下的短期爆破强度分析。采用细观力学分析方法得到单层板主方向上的强度性能;比较不同的强度失效准则后,以最大应力(变)强度准更多还原

【Abstract】 Plastic pipe reinforced by cross helically wound steel wires (PSP), which has excellent performance, is a new type of plastic-matrix steel composite pipe. PSP is composed of steel wire twined skeleton as the enhanced body and high density PE as the base. The enhanced body and the base are cohered together with a kind of high quality resin. Because of the unique structure, PSP not only integrates the advantages of high load-applying of steel pipes and good corrosion resistance of plastic pipes, but also overcomes drawbacks of plastic-matrix metal composite pipes, for example, delaminating easily under long-time alternating stress. With the high productivity and excellent performance, PSP could be used widely in various fields.Up to now, researching on PSP is only about its manufacture, assembly and application. At the same time, its mechanical properties have not been reported in literatures. So, mechanical properties of PSP, such as the stress-strain, failures and strength etc., are studied systematically in this dissertation for the first time. Based on the structural model, the failure modalities, strength and optimization of PSP are discussed. The main research results are as follows:(1) Based on the micro mechanics, the elastic parameters of PSP are obtained. The structural model of PSP consists of three continuous layers, i.e., inner PE layer, composite layer and outer PE layer. The composite layer is comprised by two monolayer plates. Elastic parameters of the monolayer were obtained with rectangle, series and parallel models and semi-rational formula of Halpin-Tsai. Then elastic constants of the composite layer and the whole pipe are calculated on the method of P.C.Chou about macro elastic modulus of Multi-Layer Boards. The results show that the hoop rigidity of PSP is enhanced obviously by steel skeleton and the axis rigidity of PSP doesn’t change much.(2) Stress analysis under different loads and performance analysis of external pressure are studied. Using secant method, elastic and elastic-plastic deformationsunder internal pressure were studied. Stress analysis of PSP under bending moment and internal pressure was also discussed. An equation was deduced to evaluate the external pressure resistivity of PSP. Good agreement between theoretical results and experimental data shows that the presented model can well predict stresses and strains of PSP, and the equation can be used to calculate the critical buckling pressure of PSP.(3) Short-time burst strength at room temperature of PSP was studied. Strength characters of monolayer in principal direction were obtained by micro mechanics. Maximum strain theory and maximum stress theory are considered as the failure criteria of the monolayer. Equations for burst strength of PSP were gained according to the failure of steel wires. The experimental results show that, calculated results are close to experimental data, their relative error is within -4.7%~6.9%, and the formula can be used for predicting the short-time burst strength well.(4) The method of parametric unitary optimization of PSP is presented in this dissertation. Influences of different design variables on strength and cost of PSP are analyzed. Based on the method of strength analysis, physical dimensions of PSP, i.e., winding angle, number of steel wires, diameter of steel wire, position of composite layer and wall thickness of PSP, are optimized. The cost can be decreased by 1.2% and 5.2% or burst pressure can be increased by 30.9% and 40.9% in virtue of optimization.更多还原