一种厚度无关的复合材料Ⅰ型分层扩展桥接律构建方法
A novel approach to construct a thickness-independent bridging law for large scale bridging in type Ⅰ delamination of composites
高佳乐 1荣俊杰 1席近远 1校金友 1文立华 1侯晓2
作者信息
- 1. 西北工业大学 航天学院,西安 710072
- 2. 中国航天科技集团有限公司,北京 100048
- 折叠
摘要
大范围纤维桥接是复合材料分层扩展中的一种重要的增韧机制,通常用R曲线和桥接牵引-分离定律表征.然而R曲线和桥接牵引-分离定律都与结构厚度有关,需用不同厚度试件分别进行实验测量.近期的研究指出:桥接现象的厚度相关性实质上是由于不同厚度结构弯曲刚度不同所造成的;将裂纹张开的转角引入,构建的桥接牵引-分离转角关系与厚度无关.但是,现有的构造方法需要试件预埋光纤测量应变,试验过程复杂.本文通过弹性约束梁模型解析推导双悬臂梁预制裂纹尖端张开位移和转角,并结合J-积分法构建桥接牵引-分离转角关系,通过实验验证该关系是厚度无关的.进一步基于这种厚度无关的桥接律,提出了一种根据单一厚度试验数据逆推其他任意厚度R曲线与桥接牵引-分离定律的方法.通过不同厚度的碳纤维/环氧树脂、芳纶纤维/环氧树脂复合材料层合板双悬臂梁试验,证明逆推出来的R曲线和桥接牵引-分离关系曲线与用试验直接测量的曲线吻合很好.本文方法基于解析模型,仅需测量载荷-位移曲线即可,避免了裂纹长度的测量以及不同厚度的多次试验,简化了试验流程,为复合材料结构性能表征提供了有力工具.
Abstract
Large-scale fiber bridging plays a crucial role in enhancing the toughness of composite structures during delamination,typically analyzed through the R-curve and the bridging traction-separation law.These metrics,however,are influenced by the specimen's thickness,necessitating separate experimental evaluations for each thickness variation.Recent research indicates that this thickness-dependency originates from the varying bending stiffness across structures of different thicknesses.By incorporating the crack opening angle,a thickness-independ-ent traction-separation and angle relationship was developed.Existing methods for establishing this relationship require embedding optical fibers to gauge the internal strain,complicating the experimental procedure.This study introduced an elastic restraint beam model to get analytical solution of the double cantilever beam(DCB)test,based on which the pre-crack tip opening displacement and deflection angle were derived.These equations,com-bined with the J-integral method,formed a thickness-independent bridging traction-separation and angle relation-ship.Experimental validation confirmed the thickness-independence of the derived bridging law.Furthermore,an iterative method was proposed to inversely calculate the R-curves and bridging traction-separation laws for any thickness based on data from a single thickness DCB experiment.Experiments on carbon fiber/epoxy resin and aramid fiber/epoxy resin composite laminates of varying thicknesses demonstrated the accuracy of the inversely deduced curves compared to direct measurements.The present method is based on an analytical model and re-quires only the measurement of load-displacement curves,avoiding the need to measure crack length and conduct multiple experiments with different thicknesses.This simplifies the experimental process and provides a powerful tool for characterizing the performance of composite material structures.
关键词
复合材料结构Ⅰ型分层/DCB试验/纤维桥接/R曲线/J-积分法Key words
type Ⅰ delamination of composite structures/DCB test/fiber bridging/R curve/J-integral method引用本文复制引用
基金项目
国家自然科学基金重点项目(52090051)
国家自然科学基金青年项目(12102349)
出版年
2024
NETL
NSTL
万方数据