二维三轴编织复合材料的开孔静力学性能及失效行为

Open-Hole Static Properties and Failure Behaviors of Two-Dimensional Triaxial Braided Composites

为考察典型二维三轴编织复合材料(2DTBC)在开孔条件下的静力学性能及失效机理,采用机器人辅助二维三轴编织及真空树脂灌注工艺成型制备了2DTBC试样,并分别考察了其在开孔拉伸(OHT)、开孔压缩(OHC)、单钉单剪(SBS)及单钉双剪(SBD)四种典型开孔静力测试下的力学响应及失效行为。结果表明:较传统层合板而言,2DTBC的开孔性能保持率显著提高,轴向及横向开孔拉伸强度保持率分别达到94.77%和96.88%,轴向及横向开孔压缩强度保持率分别达到93.25%和82.74%。OHT试样的失效模式表现为纤维束断裂、纤维束拉拔损伤、基体破坏和界面分层损伤。OHC试样的失效模式表现为纤维束屈曲失效、分层损伤和基体破坏。SBS及SBD试样的失效模式主要表现为螺钉连接处的分层、纤维束开裂及基体破坏,且试样在达到载荷峰值后没有立即失效,表现出了较好的能量吸收能力。

In order to investigate the statics properties and failure mechanism of typical two-dimensional triaxial braided composite(2DTBC)under open hole conditions,samples were prepared by robot-assisted two-dimensional triaxial braided composites and vacuum resin perfusion process.The mechanical responses and failure behaviors were investigated under four typical openhole static tests,namely,open-hole tensile test(OHT),open-hole compression test(OHC),single bolted single shearing test(SBS)and single bolted double shearing test(SBD).Results show that compared with the traditional laminates,2DTBC has significantly improved the retention rate of strength after opening hole.The retention rates of axial and transverse open hole tensile strength were 94.77%and 96.88%,and the retention rates of axial and transverse open hole compressive strength were 93.25%and 82.74%,respectively.The failure modes of OHT samples are fiber bundle fracture,fiber bundle pulling damage,matrix failure and interface delamination damage.The failure modes of OHC samples include buckling failure of fiber bundles,delamination damage and matrix failure.The failure modes of SBS and SBD samples are mainly manifested as delamination of screw joints,fiber bundle cracking and matrix destruction.Moreover,the sample does not fail immediately after reaching the peak load,showing good energy absorption capacity.