Improving the delamination bridging performance of Z-pins through the use of a ductile matrix
Improving the delamination bridging performance of Z-pins through the use of a ductile matrix
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DOI：
10.1016/j.compositesa.2022.107241
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发表时间：
2022-10
期刊：
影响因子：
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通讯作者：
E. Santana de Vega;G. Allegri;B. Zhang;I. Hamerton;S. Hallett
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文献类型：
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作者：
E. Santana de Vega;G. Allegri;B. Zhang;I. Hamerton;S. Hallett
本文提出了一个表征的影响，改变聚合物基体的Z针通过厚度增强预浸料基层压板。考虑增加断裂伸长率的四种基质系统，即：1）低玻璃化转变温度（LTG）环氧树脂; 2）高玻璃化转变温度（HTG）环氧树脂; 3）双马来酰亚胺三嗪（BT）; 4）双马来酰亚胺（BMI）。最后一个矩阵是在市售Z销中使用的矩阵。本文讨论了用前三种基体材料制造T300碳纤维Z销的方法。BT树脂被视为生产工艺的基准。进行了初步筛选的模式II桥接性能的通过厚度钢筋制造使用的三个矩阵系统。介绍了一种基于丙烯酸玻璃载体的新型实验装置，该装置允许将贯穿厚度的钢筋的失效模式可视化。初步测试显示，与基于BMI的基线对应物相比，具有最高断裂伸长率的候选物LTG Z-pin的工作失效增加了7倍。然后将LTG Z销插入准各向同性E玻璃环氧树脂层压板中，并在整个模式混合范围内表征其桥接性能。实验结果表明，LTG Z-pins提供的峰值模式I层间断裂韧性的数量级为40 kJ/m2，相比之下，由BMI Z-pins产生的28 kJ/m2。此外，LTG引脚从完全拔出到断裂的转变发生在模式混合度为0.55时，而BMI Z引脚在模式混合度为0.2时开始失效。LTG Z销的上级桥接性能与成分基体的延展性和韧性增强相关。
This paper presents a characterisation of the effect of varying the polymer matrix in Z-pin through-thickness reinforcement in pre-preg based laminates. Four matrix systems of increasing elongation at break are considered, namely: 1) a low glass-transition temperature (LTG) epoxy; 2) a high glass-transition temperature (HTG) epoxy; 3) a bismaleimide triazine (BT); 4) a bismaleimide (BMI). The last matrix is that used in commercially available Z-pins. The manufacturing of T300 carbon-fibre Z-pins employing the first three matricesviamicro-pultrusion is discussed. The BT resin is considered as a benchmark for the manufacturing process. A preliminary screening of the mode II bridging performance of through-thickness reinforcement manufactured using the three matrix systems is carried out. A novel experimental set-up based on an acrylic glass carrier, which allows the failure mode of the through-thickness reinforcement to be visualised, is introduced. The preliminary tests reveal a 7-fold increase of work-to-failure for the candidates with the highest elongation at break, LTG Z-pins, compared to their baseline BMI-based counterparts. LTG Z-pins were then inserted in quasi-isotropic E-glass epoxy laminates and their bridging performance characterised across the full mode-mixity range. The experimental results indicate that LTG Z-pins provide a peak mode I interlaminar fracture toughness of the order of 40 kJ/m2, compared to the 28 kJ/m2yielded by BMI Z-pins. Moreover, the transition from full pull-out to rupture for the LTG pins occurs at a mode-mixity of 0.55, whereas BMI Z-pins start failing at a mode-mixity of 0.2. The superior bridging performance of the LTG Z-pins is correlated with the enhanced ductility and toughness of the constituent matrixviadetailed fractographic observations.