【作者】 张群；

【导师】 李炜；

【作者基本信息】 东华大学 ， 数字化纺织工程， 2012， 硕士

【摘要】 纤维增强复合材料具有良好的比刚度、比强度和阻尼特性且密度低,已经作为一种主要的结构材料应用于航天、舰船、汽车等工程领域。复合材料的阻尼一般比大多数常见的金属高1到2个数量级,但一般也不超过2%,在工程应用中仍然偏低,需要对其进行阻尼改性处理。本课题通过制备混杂纤维复合材料和结构阻尼复合材料的方式提高复合材料的阻尼性能,并将这两种阻尼改性方法结合起来设计出新型结构阻尼复合材料。本文采用手糊模压工艺制备碳纤维／凯夫拉纤维混杂复合材料,使用动态热机械分析技术测试复合材料的损耗因子来评价材料的阻尼性能,研究了混杂比、铺层顺序和混杂方式对复合材料阻尼性能和力学性能的影响。研究结果表明：在CF/KF夹芯混杂复合材料中,面层纤维的种类和铺层数量对材料的力学性能和阻尼性能有着重要的影响。碳纤维分布于面层时,混杂复合材料具有高模量、低阻尼的特点。凯夫拉纤维分布于面层时,混杂复合材料具有低模量、高阻尼的特点。CF/KF混杂复合材料的弯曲模量随着碳纤维相对体积分数的增加而呈上升的趋势。在CF/KF层间混杂复合材料中,混杂界面数越多,混杂复合材料的阻尼性能越好。本文还研究了频率和振幅对复合材料阻尼性能的影响。结果表明：频率对复合材料的阻尼性能有较大的影响。随着频率的增加,复合材料的阻尼性能越好。振幅对复合材料阻尼性能的影响非常小。本文采用共固化工艺制备结构阻尼复合材料,研究了温度、阻尼层、阻尼层厚度和阻尼层穿孔对复合材料性能的影响。研究结果表明：粘弹性阻尼材料作为特定的铺层直接嵌入到复合材料结构中去,与复合材料共固化成型,可有效提高复合材料的阻尼性能,同时使模量有一定程度的下降。树脂和粘弹性阻尼层的界面结合情况良好,阻尼层不容易脱落。阻尼层在不同温度下的动态力学性能决定了共固化阻尼复合材料的阻尼性能。阻尼层厚度的增加可以显著提高复合材料的阻尼性能,同时会导致复合材料弯曲性能的降低。阻尼层经穿孔处理后,复合材料的阻尼性能略有下降,这种方式可以有效降低阻尼改性过程中力学性能的牺牲。最后,本文将两种阻尼改性方式结合起来,设计出新型结构阻尼复合材料。一种方法是对复合材料进行约束阻尼处理,这种方法可以有效提高复合材料的阻尼性能,且不会牺牲材料的刚度,但是增加了一定的厚度和重量。另一种方法是在含有粘弹性阻尼层的碳纤维复合材料中插入一定量的凯夫拉纤维铺层,可以显著提高复合材料的阻尼性能。更多还原

【Abstract】 Fiber reinforced composites have good specific stiffness, specific strength, damping property and low density. As structural materials, composites have been used in aerospace, ships, automobile and other engineering fields. Damping properties of composites are 10-100 times higher than most of common metals, but not exceeding 2%. They need damping modification treatment. This paper improved damping properties of composites by fabricating hybrid fibers composites and structural damping composites, designed new structural damping composites.Carbon fiber/Kevlar fiber hybrid composites are prepared by wet hand lay-up and heat pressing. We tested loss factor by thermal dynamic mechanics analysis technique to evalute damping properties of composites, and studied the influences of the hybrid ratios, stacking sequences and hybrid modes on the damping and mechanical properties of hybrid composites. The results show that the category and quantity of outermost fibers have significant influence on the damping and mechanical properties of composites. When carbon fiber works as surface layer, composites have higher bending properties and lower damping properties. When Kevlar fiber works as surface layer, composites have lower bending properties and higher damping properties. Bending modulus of CF/KF hybrid composites are on the rise with carbon fiber volume fraction increasing. The more hybrid interface number, the better damping properties of interply hybrid composites.This paper studied the influences of frequency and amplitude on the damping and mechanical properties of composites. The results show the loss factor is on the rise with test frequency increasing and amplitude has little influence on damping properties.We fabricated structural damping composites by the co-curing process, studied the influences of moulding process, temperature, damping layer, damping layer thickness and perforated damping layer on structural damping composites. The results show viscoelastic damping layer can be embeded into composites as specific layer and co-cured with composites. It can improve damping properties of composites and decrease modulus of composites. Resin and viscoelastic damping layer have well combined interface. Damping properties of co-cured damping composites depend on dynamic properties of damping layer at different temperatures. The increase of damping layer thickness can improve damping properties of structural composites and reduce bending properties of composites. Prforated damping layer decreases damping properties of composites while the bending properties of composites have an improvement.Finally, we combined two damping modification methods and designed new structural damping composites. One method is conducted by constraint damping treatment on composites. This method improves damping properties efficiently and doesn’t decrease stiffness, but increases some thickness and weight. Other method is embeding Kevlar fiber layers into structural composites with interleaved viscoelastic damping layer. This method can improve damping properties efficiently.更多还原