Bridging Effect and Efficiency of Partly-Cured Z-pin Reinforced Composite Laminates

摘要

To study the bridging effect of partly-cured Z-pin,Z-pins with different curing degrees are manufactured by controlling pultrusion parameters.A unit cell is selected to analyze the stress of Z pinned laminates and the quantitative relationship between the maximum bridging force and Z-pin diameter,embedded length,interfacial shear strength and tensile strength is acquired.The Z-pin "bridging law" test and Z-pin tensile test are carried out to study the effect of Z-pin's curing degree on bridging effect,and the bridging efficiency is defined to evaluate the reinforcement effect of Z pin.The mode I interlaminar fracture toughness (Gic) is measured by the double cantilever beam test.The experimental results show that Z-pin's co-curing with laminate matrix can improve the bridging force significantly and the fitting results show a linear relationship between Z-pin curing degree and interfacial shear strength.The three-dimensional images of the surface of pullout Z-pins indicate that the failure mode changed from totally interfacial debonding to a mixed mode.Finally,the reinforcement by partly-cured Z-pin can be used to further enhance the interlaminar toughness.Compared with completely-cured Z-pin,GIc of Z-pin with 67.6％ curing degree increases by 47.0％.