碳纤维复合绳芯拉挤工艺的实验及建模研究

发布时间：2018-05-22 13:26

本文选题：耐高温环氧树脂 + 碳纤维复合材料　；参考：《上海大学》2015年博士论文

【摘要】：随着人们对电力需求的增加,电力公司难以在原基础上通过增加传输线路的方式来增加电流以满足消费者需求,因此,需要对原使用的导线进行革新。碳纤维复合材料由于其优异的性能而广泛应用于航空航天、汽车以及基础设施等领域,有学者将玻璃/碳纤维复合材料应用于电力电缆行业,取得了良好的效果,能够用来替代传统的钢芯/殷钢芯铝绞线,这种混杂纤维增强芯比强度高、弧垂低、耐温性好,运行时能够通过增大电流的方式以满足用户使用要求。但是这种增强芯并非没有缺点,其在生产及安装过程中由于卷绕会产生内部缺陷,导致在使用的过程中发生灾难性断裂。为了增强复合芯导线的安全性能,可通过结构设计的变化,制备复合绳芯来降低内应力以及增加其韧性。本文就制备高可靠性碳纤维复合绳芯关键技术进行了实验及建模研究,主要内容如下:通过选择三种多官能团环氧树脂AG-70、AG-80、AFG-90,两种酸酐固化剂甲基六氢苯酐(MHHPA)和甲基纳迪克酸酐(MNA)以及促进剂组成六种树脂体系,对这六种体系进行详细的热分析,确定以AG-80为主体树脂,MHHPA为固化剂,将AG-80/MHHPA与促进剂和脱模剂进行多种配比下的热分析及凝胶性能测试,确定用于制备碳纤维复合绳芯的树脂基体组成及配比为:AG-80:MHHPA:2,4-EMI:INT-1890M=100:118.5:1.5:5。随后对确定的树脂基体进行非等温DSC测试,计算得到了其固化反应动力学方程,结果表明其反应符合两参数模型。通过测试不同温度下树脂基体的凝胶时间,建立了凝胶时间与设置温度之间的函数关系。通过DMA测试了树脂基体的粘弹性能,结果发现树脂基体的玻璃化转变温度随着测试频率的增加而增加,在测试温度范围内,树脂基体呈现出三个不同的状态。树脂基体的热膨胀性能测试结果表明在升温过程中的热膨胀系数也并非恒定不变,其数值是随着温度的不同而变化的。用非等温DSC方法研究了含/不含碳纤维的树脂基复合材料的放热性能,由于碳纤维的导热性能良好以及脱模剂的扩散作用,AMEI/CF体系比AMEI体系表观活化能低,动力学指前因子减小。通过外推法获得了AMEI/CF体系的特征温度,计算获得了两个体系的固化反应动力学方程,联合特征温度方程及凝胶时间与温度的函数关系可以对拉挤工艺参数的设置进行指导。对AMEI/CF体系进行了热失重测试,发现在300 oC以下时,碳纤维体积分数为58.8%的AMEI/CF体系稳定性最好。测试了不同碳纤维体积分数时的线膨胀系数,发现其随着温度的变化区别很大,当碳纤维体积分数含量为58.8%时,其线膨胀系数随着温度的变化波动最小。用DMA测试了AMEI/CF体系的粘弹性能,由于碳纤维的刚性作用,储能模量和损耗模量在玻璃态变化极小,而且其值比AMEI体系的值大得多。用数值模拟方法研究了拉挤工艺模具内碳纤维/树脂体系在非稳态情况下固化度及温度随时间的变化关系,由于孔直径(2mm)较小,且碳纤维传热性能好,发现在同一拉挤速度下,模具孔内截面上设定位置的三点温度变化趋势相同,而且温度差极小;在不同的拉挤速度下,孔内中心线的温度分布几乎相同。在30cm/min的拉挤速度下,距中心线不同距离处的固化度曲线几乎重合,在整个模具内固化度沿着牵引方向一直增大。用数值模拟方法分析了碳纤维复合芯在不同条件下的弯曲性能,发现在所给定的弯曲模式下,其应力及总位移与载荷呈线性关系,应力与样品长度呈线性关系,但是总位移与样品长度呈三次函数关系,应力及总位移与样品直径既不满足线性关系,也不满足三次函数关系,而是呈现指数函数关系,说明了应力及总位移与直径的关系更加复杂,同时给出了各种函数关系表达式。
[Abstract]:With the increase in demand for electricity, it is difficult for power companies to increase current by increasing transmission lines to meet consumer demand. Therefore, the original wire needs to be innovated. Carbon fiber composites should be widely used in aerospace, automotive, infrastructure and other fields because of its excellent performance. Some scholars have applied glass / carbon fiber composites to the power cable industry. It has achieved good results and can be used to replace the traditional steel core / aluminum strand of the Yin steel core. This hybrid fiber reinforced core has high strength, low sag and good temperature resistance. It can be used to meet the user's requirements by increasing the electric current in operation. In the process of production and installation, it can produce internal defects in the process of production and installation, resulting in disastrous fracture in the process of use. In order to enhance the safety performance of the composite core wire, the composite cords can be prepared to reduce the internal stress and increase its toughness by the change of the structure design. The key technology of fiber composite coring is studied and studied. The main contents are as follows: by selecting three kinds of multi-functional epoxy resin AG-70, AG-80, AFG-90, two kinds of anhydride curing agent methyl six hydrogen phthalic anhydride (MHHPA) and methyl Nadik anhydride (MNA) and accelerant to make up six kinds of resin systems, the six systems are analyzed in detail. It is determined that AG-80 is the main resin and MHHPA is a curing agent. The thermal analysis and gel performance test of AG-80/MHHPA with promoters and demoulding agents are used to determine the composition and ratio of the resin matrix used in the preparation of carbon fiber composite cords: AG-80:MHHPA:2,4-EMI:INT-1890M=100:118.5:1.5:5. is then used for the determination of the resin matrix. The kinetic equation of the curing reaction was obtained by the isothermal DSC test. The results showed that the reaction accorded with the two parameter model. By testing the gelation time of the resin matrix at different temperatures, the relationship between the gel time and the setting temperature was established. The viscoelastic properties of the resin matrix were tested by DMA. The results of the resin matrix glass were found. The transformation temperature increases with the increase of the test frequency. In the range of test temperature, the resin matrix presents three different states. The thermal expansion coefficient of the resin matrix shows that the thermal expansion coefficient is not constant during the heating process, and its numerical value varies with the temperature. The non isothermal DSC method is used to study the thermal expansion coefficient. The exothermic properties of the resin based composites containing / without carbon fiber are obtained. Due to the good thermal conductivity of carbon fibers and the diffusion of demoulding agents, the AMEI/CF system is lower than the apparent activation energy of the AMEI system and the kinetic pre finger factor decreases. The characteristic temperature of the AMEI/CF system is obtained by extrapolation, and the curing reaction of the two systems is calculated. The dynamic equation, the combined characteristic temperature equation and the function relationship between the gel time and the temperature can guide the setting of the pultrusion process parameters. The thermal weight loss test of the AMEI/CF system was carried out. It was found that the AMEI/CF system with the volume fraction of carbon fiber with the volume fraction of 58.8% was the best when the volume fraction of carbon fiber was below 300 oC. The coefficient of linear expansion is found to be very different with the change of temperature. When the volume fraction of carbon fiber is 58.8%, its linear expansion coefficient fluctuates with the change of temperature. The viscoelastic properties of the AMEI/CF system are measured with DMA. Because of the rigidity of carbon fiber, the energy storage modulus and loss modulus are very small in the glass state, and their values are more than AMEI. The value of the system is much larger. Numerical simulation is used to study the relationship between the curing degree and the temperature of the carbon fiber / resin system in the pultrusion mold under the unsteady state. The three point temperature change of the set position on the section of the die is found at the same pultrusion speed, because of the smaller hole diameter (2mm) and the good heat transfer performance of the carbon fiber. The trend is the same, and the temperature difference is very small. At different pultrusion speed, the temperature distribution of the center line in the hole is almost the same. At the pultrusion speed of 30cm/min, the curing degree curve at different distance from the center line almost coincides, the solid degree in the whole die has been increased along the traction direction. The carbon fiber composite is analyzed by the numerical simulation method. The bending behavior of the core under different conditions is found to have a linear relationship between the stress and the total displacement under the given bending mode. The stress is linear with the length of the sample, but the total displacement has three functional relations with the length of the sample. The stress and the total displacement do not satisfy the linear relationship with the sample diameter and do not meet the three function relations. It shows exponential function relationship, which shows that the relationship between stress and total displacement and diameter is more complicated. At the same time, expressions of various functional relations are given.
【学位授予单位】：上海大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TB33;TM205

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