碳纤维梯度分布对水泥基材料热应力分布的影响

【作者】 张海涛；

【导师】 杨久俊；

【作者基本信息】 郑州大学 ， 材料学， 2006， 硕士

【摘要】 目前水泥基材料已成为应用量最大和使用最广泛的人造建筑材料。随着大量水泥基材料结构因使用环境、荷载等原因，其使用寿命大幅度降低，特别是道路混凝土，由于采用撒盐融雪化冰，加速了混凝土的破坏，耐久性较差。碳纤维水泥基材料是近年来在国内外发展较快的一种新型导电水泥基材料，利用其电热效应用于道路混凝土的融雪化冰。然而导电水泥基材料中发热层与非发热层之间会产生热应力，从而引起材料破坏，耐久性下降。本文引入组分梯度的概念，通过碳纤维梯度分布研究其对水泥基材料力学性能、导电性能及热应力分布的影响，得到如下结果： (1)碳纤维梯度分布，水泥基材料力学性能明显改善：研究结果表明，碳纤维梯度分布水泥基材料的3d和28d抗折强度显著高于碳纤维均匀分布和层状分布材料，其中碳纤维掺量为0.3％时，碳纤维梯度分布试件28d抗折强度与碳纤维层状分布、均匀分布试件相比分布提高。碳纤维梯度分布对水泥基材料的抗压强度影响不大。碳纤维水泥基材料的弹性模量随碳纤维掺量的增加而下降，其泊松比随碳纤维掺量的增加而增加； (2)碳纤维梯度分布，水泥基材料导电性能显著提高：当碳纤维掺量为0.3％和0.4％时，碳纤维梯度水泥基材料与均匀分布相比，其导电性能显著提高。当纤维掺量大于0.8％时，碳纤维梯度分布与均匀相比无明显变化。对不同碳纤维掺量水泥基材料的热工性能研究结果表明，其热膨胀系数随碳纤维掺量的增加而降低，导热系数随碳纤维掺量的增加而降低； (3)碳纤维梯度分布，水泥基材料热应力分布显著缓和：采用ansys9.0有限元软件对碳纤维层状分布和梯度分布试件在通电发热下应力场模拟分析表明，碳纤维层状分布和梯度：分布试件应力差(△s)分别为3.51912MPa和1.4247MPa，碳纤维梯度分布试件的△s为碳纤维层状分布的40.49％。在相同温度条件下对相同厚度不同长度碳纤维层状分布和梯度分布试件水泥基材料的层间热应力研究表明，其最大△s随试件尺寸的增加而增加。当试件长度大于更多还原

【Abstract】 Cement base material is the maximum and most widely used man-made building material in nowadays. It is easy damaged by the environment reason and over load. Especially the concrete used in highway, which is often face with the salt to melt snow. Carbon fiber reinforced cement material is the new way to melt snow, as the electrothermal it have, and is quickly developing technology in these years. However, the thermal stress caused by the joint between heating layer and no-heating layer would crack the bond and descend durability. In this paper, the concept of FGM is firstly applied in cement-based materials to study the effect of carbon fiber gradient distribution in cement-based materials on mechanical property, conductive property and thermal stress distribution.(1) The cement based material’s mechanical property is improved if carbon fiber gradient distribution. In this paper, we found that, the carbon fiber distribution in gradient have clearly higher flexural strength than distribution in uniform, but the compressive strength have not changed much. As the number of carbon fiber increased in the cement based material, its modulus of elasticity decrease, and poisson ratio raised.(2) The cement based material’s conductive property is improved if carbon fiber gradient distribution. When the usage of carbon fiber get to 0.3% and 0.4%, the carbon fiber gradient distribution on the cement material have obvious higher conductive property than the uniform one, but the conductive will keep the same level when the usage get to 0.8%. the research on thermal property indicated that, as the number of carbon fiber increased in the cement based material, its coefficient of thermal expansion decrease, same with coefficient of thermal conduction.(3)The cement based material’s thermal stress distribution is released if carbon fiber gradient. In this part, we use the software of finite element analysis, called ansys9.0, to imitation the field of stress caused by energized heat in the carbon fiber gradient distribution and uniform distribution on the cement based materials.更多还原