Tensile properties and failure mechanism of carbon fiber reinforced epoxy composite with resin rich defects
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摘要: 对含有因局部纤维断裂形成的富树脂缺陷的碳纤维/环氧树脂复合材料拉伸性能进行研究,分析缺陷位置与试样拉伸性能的对应关系发现:当富树脂缺陷大小相同位置不同,拉伸强度从高到低分别是:缺陷位于试样1/3处,缺陷位于试样几何中心时,缺陷位于试样1/2处的边缘时。当缺陷位于同一位置时,拉伸强度随缺陷尺寸的增大而降低。通过计算机断层扫描技术(CT)检测缺陷实际尺寸位置,采用有限元仿真技术建立含缺陷的碳纤维/环氧树脂复合材料拉伸强度性能预测模型,预测结果与实验值的误差小于10%,说明了该有限元模型的可靠性,并结合模拟结果分析复合材料的失效机制。
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关键词:
- 有限元仿真 /
- 碳纤维/环氧树脂复合材料 /
- 富树脂缺陷 /
- 失效机制 /
- 拉伸强度
Abstract: The tensile properties of carbon fiber reinforced epoxy composite with resin rich defects caused by local fiber fracture were studied. The corresponding relationship between defect location and tensile properties was analyzed. It is found that the maximum and minimum tensile strength are observed when the defect is located at 1/3 of the sample and 1/2 of the edge of the sample, respectively whilst the intermediate strength is seen at geometric center of the sample provided the same defect size. When the defect is in the same position, the tensile strength decreases with the increase of defect size. The actual size and location of defects are detected by computed tomography (CT), and the tensile strength prediction model of carbon fiber reinforced epoxy composite with defects is established by using finite element simulation. The error between the simulation values and the experimental values is less than 10%, which shows the reliability of the finite element model. Moreover, the failure mechanism of the composites is analyzed with the simulation results. -
图 3 CF/EP复合材料中缺陷尺寸CT扫描结果与设计值:(a) 缺陷孔径CT检测结果与设计值;(b) 缺陷孔厚CT检测结果与设计值;(c) 缺陷埋深CT检测结果与设计值;(d) 缺陷尺寸CT检测结果与设计值的误差
Figure 3. CT scanning results and design values of defect size in CF/EP composite: (a) CT detection results and design values of defect diameter; (b) CT detection results and design values of defect hole thickness; (c) CT detection results and design value of defect buried depth; (d) Error between CT detection result and design value of defect size
图 7 含缺陷CF/EP复合材料拉伸强度实验值和模拟值:(a) 1#试样实验结果与模拟结果的位移-载荷曲线;(b) 1#~7#试样拉伸强度实验值和模拟值及实验值和模拟值之间的误差
Figure 7. Experimental and simulated values of tensile strength of CF/EP composite with defects: (a) Displacement-load curve of 1# sample experimental results and simulated results; (b) Experimental value and simulated value of tensile strength of sample 1#-7# and error between them
图 10 CF/EP复合材料2#试样拉伸断口SEM图像:((a)~(d)) 距缺陷分别为0.5 mm、1.5 mm、2 mm和2.5 mm的4个位置的SEM图像;((e), (f)) 图10(a)~10(c) 中横向纤维断裂和纤维束拔出断裂SEM图像;((g), (h)) 图10(d)中横向纤维处与轴向纤维处的SEM图像
Figure 10. SEM images of tensile fracture of 2# sample of CF/EP composite: ((a)~(d)) Four positions with a distance of 0.5 mm, 1.5 mm, 2 mm and 2.5 mm from the defect, respectively; ((e), (f)) Transverse fiber fracture and fiber bundle pull-out fracture in Fig.10(a)~10(c); ((g), (h)) Transverse fiber and the axial fiber in Fig.10(d)
表 1 CF/EP复合材料1#~7#试样中缺陷描述和各试样的图标
Table 1. Description of defects in 1#-7# sample of CF/EP composite and icons of each sample
Numbering Defect description Defect diagram 1# A circular defect of R=2 mm at the geometric center of the sample 2# A circular defect of R=4 mm at the geometric center of the sample 3# Semi-circular defect of R=4 mm at the center of one side of the sample 4# A circular defect of R=4 mm at the center of one side of the sample 5# A circular defect of R=2 mm located at 1/3 of the sample 6# A circular defect of R=4 mm located at 1/3 of the sample 7# No defects Note: R—Radius. 表 2 环氧树脂模拟参数
Table 2. Simulation parameters of epoxy resin
Property Value Young’s modulus/GPa 3.78 Poisson’s ratio 0.38 Tensile strength/MPa 80 Compressive strength/MPa 247 Shear strength/MPa 58 表 3 环氧树脂塑性段数据
Table 3. Data of plastic section of epoxy resin
Yield stress/GPa Plastic strain 1 0.19977 0 2 0.29768 0.0024741 3 0.3956 0.01144 4 0.50167 0.32359 5 0.6023 0.080176 6 0.69749 0.17182 7 0.79812 0.32922 8 0.90419 0.59919 9 0.95587 0.79942 10 1.0021 1.0046 表 4 CF/EP复合材料模拟参数
Table 4. Simulation parameters of CF/EP composite
Property Value Meridional Young's modulus E1/GPa 68 Latitudinal Young's modulus E2/GPa 66 Transverse Young's modulus E3/GPa 42 Poisson's ratio 0.25 In-plane shear modulus G12=G13/GPa 5.4 Out-plane shear modulus G23/GPa 4.5 Longitudinal tensile strength/MPa 686 Longitudinal compressive strength/MPa 401 Transverse tensile strength/MPa 610 Transverse compressive strength/MPa 400 Longitudinal shear strength/MPa 117 Transverse shear strength/MPa 117 表 5 含缺陷CF/EP复合材料拉伸强度实验值与模拟值
Table 5. Experimental and simulated values of tensile strength of CF/EP composite with defects
Numbering 1# 2# 3# 4# 5# 6# 7# Experimental tensile strength/MPa 644.5 576.8 668.3 598.2 638.7 478.7 697.1 Simulated tensile strength/MPa 693.1 612.9 717.6 648.1 708.1 507.4 742.8 表 6 CF/EP复合材料1#~7#试样应力-应变分布云图
Table 6. Stress and strain distribution patterns of 1#-7# sample of CF/EP composite
Defect diagram
Stress and strain distribution patternStress distribution Strain distribution Stress distribution Strain distribution Stress distribution Strain distribution Stress distribution Strain distribution Stress distribution Strain distribution Stress distribution Strain distribution Stress distribution Strain distribution -
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