RTM成型聚酰亚胺复合材料机匣安装边结构强度性能

Strength properties of flange structure of polyimide composite casing manufactured by RTM

针对复合材料机匣安装边结构,设计一种采用RTM工艺成型的T800级碳纤维增强聚酰亚胺树脂基复合材料层合结构试件;对其进行有限元数值仿真分析,当施加单向拉伸载荷时,计算得到的破坏载荷为21.7 kN,最大应变出现在安装边转角位置,说明转角区为试件承载时的薄弱区域。采用超声C扫描和光学显微镜对制备的试件转角区内部质量进行分析,结果表明:试件转角区整体内部质量良好,无明显分层缺陷,局部可见百微米级孔隙,主要集中在近表面和直角填塞区。试件平均拉伸破坏载荷为19.81 kN,与数值仿真结果相近;在25%破坏载荷条件下循环疲劳实验24000次后,拉伸破坏载荷仍为19.94 kN,说明疲劳实验对试件的承载能力没有影响;拉伸实验后部分试件转角区在显微镜下可见轻微分层和裂纹缺陷,但所有试件均未发生目视可见损伤,表明试件在出现分层缺陷后仍能继续承载。

According to the flanged structure of composite casing,a typical sample with laminated structure manufactured by RTM process was designed using T800 grade carbon fiber fabrics reinforced polyimide composite.The strength property under the uniaxial tension condition was simulated by finite element method,and the calculated fracture load was 21.7 kN.The maximum strain was appeared at the corner of flanged structure,indicated that the corner area of flanged structure was weak relatively.Ultrasonic C-scan and optical microscope methods were applied to analyze the internal quality of the corner area.The results show that the overall internal quality of the sample corner area is good without obvious delamination defects.However,some micro-pores enriched at near surface and the fill region are still visible.The measured average tensile fracture load is 19.81 kN,and that is very close to the calculated value.After cyclic loading with 25%of the fracture load for 24000 times,the residual tensile fracture load is still 19.94 kN,this result means fatigue test has no effect to the mechanical property of the samples.Little interlayer defects and cracks happened in several samples at the corner area,but no visual damage.It shows that the sample can still bear the load after the delamination defects appear.