考虑纤维损伤的大孔口层合板缝合补强等效力学模型

Equivalent model of stitching reinforcement on composite laminates with a large hole considering fiber damage

针对含大孔口层合板(层合板宽度D与开孔半径R的比例D/R<6)缝合补强,考虑缝合线对面内纤维造成弯曲、断裂及针脚处夹杂和富树脂区的影响,利用有限元软件建立了大孔口层合板缝合补强模型。在拉伸载荷作用下,计算了不同缝合参数(针距、行距、边距、缝合线直径、缝合线张力)对层合板力学性能的影响。并将不同缝合参数对面内纤维造成的损伤等效为孔径的扩展,建立其等效开孔无边缘效应层合板有限元模型,得出了缝合补强时不同缝合参数对层合板整体承载能力的影响规律。针距越小,层合板承载能力越低;当针距小于3.14mm时,随着边距的增大,层合板承载能力单调减小;当针距介于3.14mm与6mm之间时,随着边距的增大,层合板承载能力呈现出类似于正弦函数的变化形式,且整体趋势增大;当针距大于6mm时,随着边距的增大,层合板承载能力单调增大;当中心圆孔的0°与90°位置存在针脚缺陷时,易造成层合板提前破坏。

Taking into account the effect of the stitching threads on the bending and breaking of the in-plane fibers,the inclusion of stitch holes and resin-rich zones,the research focuses on the stitching reinforcement for the composite laminates containing a large hole(The ratio of laminate’s width D and diameter R of the open-hole D/R<6).The finite element simulating calculation was carried out on the stitching reinforcement for composite laminates containing a large circular hole.On the tensile load,the effects of different stitch parameters(stitching needle distance,row spacing,edge distance,diameter and tension)on the mechanical properties of the laminate were calculated.And the damage caused by different stitch parameters to the in-plane fibers is regarded as equivalent to the expansion of the diameter of the hole.The finite element model of the equivalent modal without edge effect laminates was established,and the principle of the influences on the overall mechanical properties of the laminate by different stitch parameters was investigated.The less distance of the stitching needle,the poorer the mechanical properties of the laminates.When the stitching needle distance is less than 3.14 mm,the mechanical properties of the laminate decrease monotonically with the increase of the edge distance.When the stitching needle distance is between 3.14 mm and 6 mm,with the increase of the edge distance,the mechanical properties of the laminate present a trend similar to sine function,and the overall trend is increasing.When the needle distance is more than 6 mm,with the increase of the edge distance,the mechanical properties of the laminates increase monotonically.At the positions of 0°and 90°of the central hole,the defect of the stitch holes causes the early failure of the laminates easily.