碳—芳纶混杂二维编织复合材料冲击性能实验研究
发布时间：2018-11-24 10:55
【摘要】：为了充分利用二维编织物生产效率高、纤维空间弯曲扭转程度低、纤维性能损伤少、可设计性强等优点,通过设计碳纤维和芳纶纤维混杂结构,试图提高复合材料抗冲击性能。本课题首次以碳纤维和芳纶纤维二维编织物混杂铺层复合材料为研究对象,主要对碳-芳纶混杂二维编织层合复合材料的冲击性能及冲击后压缩性能进行实验研究,来探究混杂结构对冲击性能的影响。本文设计制备了层间混杂、夹芯混杂、非对称混杂三种碳-芳纶混杂二维编织复合材料层板以及用作对比的碳纤维二维编织复合材料层板。通过落锤低速冲击实验研究了混杂结构对其冲击载荷、冲击吸收能量、冲击损伤形貌等抗冲击性能的影响,且采用超声C扫描和B扫描成像揭示了层板内部冲击损伤,初步判断材料的抗冲击性能。发现碳纤维层板的峰值载荷最高,混杂结构层板峰值载荷稍有降低,然而,混杂结构层板的韧性指数均大于碳纤维层板;在三种混杂结构层板中,层间混杂层板同时具有较高的峰值载荷和韧性指数。超声C扫描和B扫描成像结果显示,碳纤维层板损伤深度最大,冲击背面出现纤维抽拔断裂;层间混杂层板损伤深度比碳纤维层板小,但冲击正面损伤范围大于碳纤维层板;而夹芯混杂层板出现最多的分层裂纹,非对称混杂层板出现内部分层现象,表明层间混杂结构能有效地平衡不均衡的层间弯曲应力,抵抗落锤的冲击。在此基础上,进行了面内轴向压缩实验和冲击后压缩实验,在实验过程中首次采用数字图像相关(DIC)方法获取试样面内轴向压缩全场应变。将冲击前后的压缩性能进行对比,分析得出剩余压缩性能较好的复合材料,从而得出具有较优抗冲击性能的混杂结构复合材料试样。压缩结果表明,在较高面内轴向压缩载荷下,载荷会偏离试样轴向(偏心),出现面外位移,并同时产生压缩应变和弯曲拉伸应变。碳纤维层板应变分布主要是弯曲拉伸应变,其它三种混杂结构层板应变分布主要是压缩应变,说明芳纶纤维增加了复合材料韧性,层板塑性增加,轴向压缩载荷偏离小。对比无冲击损伤面内轴向压缩和冲击后压缩结果,发现碳纤维层板压缩强度和压缩模量下降最少,对低速冲击损伤最不敏感,表现出较高的冲击损伤容限。在三种混杂结构中,层间混杂下降最少,DIC云图中弯曲拉伸应变最少、压缩载荷分配均匀,说明层间混杂能提供较好的抵抗弹性变形能力以及抗失效能力。
[Abstract]:In order to make full use of the advantages of high production efficiency of two-dimensional braided fabric, low bending and torsion degree of fiber space, less damage to fiber properties and strong designability, the hybrid structure of carbon fiber and aramid fiber was designed to improve the impact resistance of composites. For the first time, the impact properties and post-impact compression properties of carbon fiber and aramid fiber composites were studied in this paper, in which carbon fiber and aramid fiber two-dimensional braided hybrid laminated composites were used as the object of study, and the impact properties and post-impact compression properties of carbon-aramid fiber hybrid two-dimensional braided composites were studied. To explore the impact of hybrid structure on the impact properties. In this paper, three kinds of carbon-aramid hybrid two-dimensional braided composite laminates, interlaminar hybrid, sandwich hybrid, asymmetric hybrid, and carbon fiber two-dimensional braided composite laminates for comparison were designed and fabricated. The effects of hybrid structure on impact load, energy absorption and morphology of impact damage were studied by low speed impact test, and the impact damage of laminates was revealed by ultrasonic C scan and B scan imaging. The impact resistance of the material is preliminarily judged. It is found that the peak load of CFRP is the highest and the peak load of hybrid laminate is slightly reduced. However, the toughness index of CFRP is higher than that of CFRP. Among the three kinds of hybrid laminates, the interlaminar hybrid laminates have high peak load and toughness index at the same time. The results of ultrasonic C scan and B scan showed that the damage depth of carbon fiber laminates was the largest and the fiber pull-out fracture appeared on the back of the impact, and the damage depth of interlaminar hybrid laminates was smaller than that of carbon fiber laminates, but the range of impact front damage was larger than that of carbon fiber laminates. However, there are most delamination cracks in sandwich hybrid laminates and internal delamination in asymmetric hybrid laminates, which indicates that the interlaminar hybrid structures can effectively balance the uneven interlaminar bending stress and resist the impact of drop hammer. On this basis, in-plane axial compression experiments and post-impact compression experiments were carried out. In the process of the experiment, the in-plane axial compression full-field strain was obtained by digital image correlation (DIC) method for the first time. By comparing the compressive properties before and after impact, the composites with good residual compressive properties were obtained, and the hybrid composite specimens with better impact resistance were obtained. The compression results show that under higher in-plane axial compression load, the load deviates from the axial (eccentric) direction of the specimen, resulting in out-of-plane displacement, and the compression strain and the bending tensile strain are produced at the same time. The strain distribution of carbon fiber laminates is mainly flexural tensile strain, while the other three hybrid structures are mainly compressive strain, which indicates that aramid fiber increases the toughness of composites, increases the plasticity of laminates, and reduces the deviation of axial compression load. Compared with in-plane compression without impact damage and compression after impact, it is found that the compression strength and modulus of carbon fiber laminates decrease least, and they are the least sensitive to low-velocity impact damage, showing a higher impact damage tolerance. Among the three hybrid structures, the interlaminar hybrid decreases the least, the DIC cloud diagram shows that the bending tensile strain is the least, and the compression load distribution is uniform, which indicates that the interlaminar hybrid can provide better resistance to elastic deformation and failure resistance.
【学位授予单位】：天津工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB332
本文编号：2353418
[Abstract]:In order to make full use of the advantages of high production efficiency of two-dimensional braided fabric, low bending and torsion degree of fiber space, less damage to fiber properties and strong designability, the hybrid structure of carbon fiber and aramid fiber was designed to improve the impact resistance of composites. For the first time, the impact properties and post-impact compression properties of carbon fiber and aramid fiber composites were studied in this paper, in which carbon fiber and aramid fiber two-dimensional braided hybrid laminated composites were used as the object of study, and the impact properties and post-impact compression properties of carbon-aramid fiber hybrid two-dimensional braided composites were studied. To explore the impact of hybrid structure on the impact properties. In this paper, three kinds of carbon-aramid hybrid two-dimensional braided composite laminates, interlaminar hybrid, sandwich hybrid, asymmetric hybrid, and carbon fiber two-dimensional braided composite laminates for comparison were designed and fabricated. The effects of hybrid structure on impact load, energy absorption and morphology of impact damage were studied by low speed impact test, and the impact damage of laminates was revealed by ultrasonic C scan and B scan imaging. The impact resistance of the material is preliminarily judged. It is found that the peak load of CFRP is the highest and the peak load of hybrid laminate is slightly reduced. However, the toughness index of CFRP is higher than that of CFRP. Among the three kinds of hybrid laminates, the interlaminar hybrid laminates have high peak load and toughness index at the same time. The results of ultrasonic C scan and B scan showed that the damage depth of carbon fiber laminates was the largest and the fiber pull-out fracture appeared on the back of the impact, and the damage depth of interlaminar hybrid laminates was smaller than that of carbon fiber laminates, but the range of impact front damage was larger than that of carbon fiber laminates. However, there are most delamination cracks in sandwich hybrid laminates and internal delamination in asymmetric hybrid laminates, which indicates that the interlaminar hybrid structures can effectively balance the uneven interlaminar bending stress and resist the impact of drop hammer. On this basis, in-plane axial compression experiments and post-impact compression experiments were carried out. In the process of the experiment, the in-plane axial compression full-field strain was obtained by digital image correlation (DIC) method for the first time. By comparing the compressive properties before and after impact, the composites with good residual compressive properties were obtained, and the hybrid composite specimens with better impact resistance were obtained. The compression results show that under higher in-plane axial compression load, the load deviates from the axial (eccentric) direction of the specimen, resulting in out-of-plane displacement, and the compression strain and the bending tensile strain are produced at the same time. The strain distribution of carbon fiber laminates is mainly flexural tensile strain, while the other three hybrid structures are mainly compressive strain, which indicates that aramid fiber increases the toughness of composites, increases the plasticity of laminates, and reduces the deviation of axial compression load. Compared with in-plane compression without impact damage and compression after impact, it is found that the compression strength and modulus of carbon fiber laminates decrease least, and they are the least sensitive to low-velocity impact damage, showing a higher impact damage tolerance. Among the three hybrid structures, the interlaminar hybrid decreases the least, the DIC cloud diagram shows that the bending tensile strain is the least, and the compression load distribution is uniform, which indicates that the interlaminar hybrid can provide better resistance to elastic deformation and failure resistance.
【学位授予单位】：天津工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB332
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