双马树脂基复合材料低速冲击响应及冲击后压缩行为研究

Low velocity impact response and post impact compression behavior of BMI matrix composites

制备了新型聚醚砜(PES)点阵附载U3160的ES^(TM)-fabric织物,PES附载量分别为15(ES-15),25(ES-25),35(ES-35)g/cm^(2)。采用RTM工艺制备了ES^(TM)-fabric织物增强双马来酰亚胺树脂(牌号:6421)基复合材料(ES^(TM)-fabric/6421),对其进行动态力学热分析(DMTA),还进行了冲击阻抗及冲击后压缩性能研究,并利用荧光显微镜分析其增韧机理,同时研究对比了未增韧U3160织物增强6421树脂基复合材料(ES-0)的性能。DMTA分析结果显示,ES-0仅有一个源于BMI基体树脂的玻璃化转变温度(T_(g)),增韧后复合材料出现了两个T_(g):191~195℃的松弛峰源于增韧剂PES,230~250℃的松弛峰源于BMI基体树脂。低速冲击结果显示,ES-0试样的初始损伤载荷(DTL)降低非常显著。增韧复合材料的DTL远高于ES-0试样,且与最高峰值载荷相同;随着增韧剂增多,DTL增大,冲击损伤面积减小。荧光显微结果显示:ES-0试样的冲击损伤以分层破坏为主。增韧复合材料在压头下方产生了大量层内和层间基体裂纹,且冲击背面的铺层破裂更加严重,其锥形冲击损伤范围要小于ES-0试样。ES-0试样的冲击后压缩强度(CAI)为144.66 MPa,增韧复合材料ES-15,ES-25和ES-35的CAI值分别依次增大为205.85,265.74 MPa和275.14 MPa。ES-0试样经冲击后压缩破坏后结构中出现了大量分层,结构无显著的劈裂;ES-15试样存在大量的纤维铺层劈裂及显著的基体裂纹;ES-25试样和ES-35试样以铺层剪切破坏为主,这些损伤会吸收大量能量,从而导致高的CAI值。

A novel kind of lattice-distributed ES^(TM)-fabrics was developed by using polyethersulfone(PES)and U3160.The loading amounts of PES on ES^(TM)-fabrics are 15 g/cm^(2)(ES-15),25 g/cm^(2)(ES-25),35 g/cm^(2)(ES-35),respectively.ES^(TM)-fabrics reinforced BMI resin(trademarks:6421)matrix composites(ES^(TM)-fabric/6421)were prepared through RTM process.Dynamic mechanical thermal analyses(DMTA)and impact resistance as well as residual strength of ES^(TM)-fabric/6421 were studied and the toughened mechanism was analyzed by fluorescence microscope.An untoughened 6421 BMI resin matrix composite(ES-0)reinforced by neat U3160 fabrics was studied to compare performance of composites as well.The results of DMTA show that ES-0 has only one glass transition temperature(T_(g))representing pure BMI resin.The toughened composites exhibit two T_(g):the relaxation peak appearing at 230-250℃represents toughener PES phase and the relaxation peak appearing at 191-195℃represents BMI phase.The results of low velocity impact testing show that the initial damage threshold load(DTL)is decreased significantly.DTL of toughened composites is far greater than ES-0 sample,which is the same as maximum peak load.With the increase of PES loading in toughened composites,DTL are increased and the projected delaminated areas are decreased.Fluorescence microscopic results of the specimens after low velocity impact show that the major impact failure of ES-0 sample is delamination.The toughened composites exhibit a great deal of interlaminar and intralaminar matrix crack under the impactor as well as more serious ply splitting on the back surface of specimens,which conical damage is less than ES-0 sample.The compression strength after impact(CAI)of ES-0 sample was 144.66 MPa while CAIs of the toughened composites ES-15,ES-25 and ES-35 increased to 205.85 MPa,265.74 MPa along with 275.14 MPa,respectively.Fluorescence microscopic results of the CAI specimens reveal that ES-0 sample has massive delamination damage without ply splitting.A lot of ply splitting and obvious matrix cracks appear in ES-15 sample.The major impact failure of ES-25 and ES-35 samples is ply shear damage.These damage modes can absorb massive energy that lead to the higher CAI of the toughened composites.