Effect of gap and overlap on mode Ⅱ interlaminar fracture toughness of automated fiber placement prepreg laminates  

作　　者：Fan ZHANG Xin LIU Yaoyao YE Qisen CHEN Qiang XU Yunbo BI 

机构地区：[1]China State Key Laboratory of Fluid Power and Mechatronic System,School of Mechanical Engineering,Zhejiang University,Hangzhou 310027,China [2]Key Laboratory of Advanced Manufacturing Technology of Zhejiang Province,School of Mechanical Engineering,Zhejiang University,Hangzhou 310027,China

出　　处：《Chinese Journal of Aeronautics》2023年第6期390-401,共12页中国航空学报（英文版）

基　　金：the Fundamental Research Funds for the Central Universities, China (No. 2019FZA4001)

摘　　要：Automated Fiber Placement(AFP)technology facilitates the manufacturing process of composite structures with complex geometry owing to its high efficiency and accuracy.However.the unavoidable imperfections induced by the automated layup method bring challenges to the stability of the final mechanical properties of composites.The influence of AFP-induced gaps and overlaps on the modeⅡinterlaminar fracture process of oven-cured laminates is experimentally investigated and explicitly revealed.End-Notched Flexure(ENF)tests were performed to measure the interlaminar fracture toughness of unidirectional laminates under three different defect configurations,namely"Gap""Overlap"and"Gap&Overlap".A marginal decline(about-1.2%in non-precracked tests,-5.1%in precracked tests)and an obvious increase(about 15.2%in nonprecracked tests,5.2%in precracked tests)in fracture toughness were observed for the"Gap"group and the"Overlap"group,respectively.Fractographic studies which involve the metallographic observation and Scanning Electron Microscopy(SEM)observation revealed that the increases in fracture area and crack length helped improve the fracture toughness of the Overlap"group.However,the resin-rich area with high porosity induced by gaps was detrimental to the delamination resistance.To capture the interlaminar stress distribution local to imperfections,a three-dimensional numerical model was established.Gap defects facilitate the local delamination process,and the overlap defect postpones the damage onset and the propagation.

关 键 词：Automated Fiber Placement(AFP) Defects DELAMINATION Fracture toughness LAMINATES 

分 类 号：V262[航空宇航科学与技术—航空宇航制造工程] TB33[一般工业技术—材料科学与工程]