针刺/缝合多尺度联锁复合材料Ⅱ型层间力学行为

Mode Ⅱ interlaminar mechanical behavior of needled/stitched multiscale interlocking composites

针刺/缝合多尺度联锁复合材料具有优异的层间性能,在航天热结构复合材料中得到越来越多的应用,然而,缝合工艺对于针刺复合材料双切口层间剪切(DNS)性能的影响还不清楚。以石英缎纹基布、石英斜纹半切布为原料,设计制备了3种缝合矩阵、4种缝合纤维束的石英纤维增强树脂基针刺/缝合多尺度联锁复合材料,测试并分析了复合材料的DNS性能。采用Micro-CT对织物内部结构进行表征,同时通过扫描电镜(SEM)观察试样断口形貌,阐明层间增强机制。使用内聚力模型(Cohesive zone model,CZM)结合Abaqus软件进一步探究针刺/缝合多尺度联锁复合材料的DNS行为,预测材料的极限破坏强度。研究结果表明:缝合工艺的引入极大地改善了复合材料的层间性能,其DNS的破坏载荷最大可达到32.73 MPa,相比针刺复合材料提升了86.46%。针刺/缝合多尺度联锁复合材料DNS的主要破坏方式是基体开裂、纤维束的脆性断裂和拔出。同时,模拟结果和针刺/缝合多尺度联锁复合材料的DNS实验结果吻合较好,误差最大不超过8%,证明本文建立的内聚力模型能够有效预测针刺/缝合多尺度联锁复合材料的层间剪切性能。

Needled/stitched multi-scale interlocking composites have excellent interlaminar properties and are increasingly used in aerospace thermal structure composites.However,the effect of stitch technology on double incision interlaminar shear(DNS) performance of needle composites remains unclear.Using quartz satin fabric and quartz twill half-cut fabric as materials,quartz fiber-reinforced resin-based needle/stitch multi-scale interlocking composites with three kinds of stitch pattern and four kinds of stitch fiber bundles were designed and prepared.The DNS performance of the composite was tested and analyzed.The internal structure of the fabric was characterized by micro-CT,and the fracture morphology of the sample was observed by scanning electron microscopy(SEM) to clarify the mechanism of interlayer strengthening.The DNS behavior of needled/stitched multiscale interlocking composites was further investigated by cohesive zone model(CZM) and Abaqus software,and the ultimate failure strength was predicted.The results show that the introduction of stitch technology greatly improves the interlamellar properties of the composite,and the maximum failure load of DNS reaches 32.73 MPa,which is 86.46% higher than that of the needled composite.The main failure modes of multi-scale interlocking composite DNS are matrix cracking,brittle fracture and pulling out of fiber bundle.At the same time,the simulation results are in good agreement with the DNS experimental results of needled/stitched multi-scale interlocking composites,and the maximum error is less than 8%,which proves that the cohesion model established in this paper can effectively predict the interlaminar shear performance of needled/stitched multi-scale interlocking composites.