Electrical-mechanical coupling behaviors and thermal-resistance effects of 3D braided composites under external loads are important for structural health monitoring(SHM). Electrical conductivity and electrical-mechani...Electrical-mechanical coupling behaviors and thermal-resistance effects of 3D braided composites under external loads are important for structural health monitoring(SHM). Electrical conductivity and electrical-mechanical coupling behaviors of 3D braided carbon fiber/epoxy composites under uniaxial tension were reported. It was found that the transverse resistance decreased and the axial resistance increased with the increasing braiding angle. The fractional change in resistance increased linearly as the strain was below 1.0%, and the nonlinearity appeared when the strain exceeded 1.0%. The negative temperature coefficient(NTC) effect was observed before the glass transition temperature Tg of epoxy resin, while there was a positive temperature coefficient(PTC) effect after Tg.展开更多
Polymer matrix types of fiber hybrid composites are key factors to improve ballistic impact damage tolerances.Here we report ballistic penetration damages of Kevlar/ultra-high molecular weight polyethylene(UHMWPE)hybr...Polymer matrix types of fiber hybrid composites are key factors to improve ballistic impact damage tolerances.Here we report ballistic penetration damages of Kevlar/ultra-high molecular weight polyethylene(UHMWPE)hybrid composites with thermoplastic polyurethane(PU)matrix.The hybrid composites were penetrated by fragment-simulating projectiles(FSPs)using an air gun impact system.The effects of stacking sequences on the ballistic performance of hybrid composites were analyzed.Two types of specific energy absorption(the energy absorption per unit area density and the energy absorption per unit thickness)were investigated.It was found that the main damage modes of PU hybrid composites were fiber breakage,matrix damage,fiber pullout and interlayer delamination.The instantaneous deformation could not be used as a reference index for evaluating the ballistic performance of the target plate.The energy absorption process of the PU hybrid composites showed a nonlinear pattern.The hybrid structure affected the specific energy absorption of the materials.展开更多
This paper reports the structural effects of three-dimensional(3-D)angle-interlock woven composite(3DAWC)undergoing three-point bending cyclic loading from experimental and finite element analysis(FEA)approaches.In ex...This paper reports the structural effects of three-dimensional(3-D)angle-interlock woven composite(3DAWC)undergoing three-point bending cyclic loading from experimental and finite element analysis(FEA)approaches.In experiment,the fatigue tests were conducted to measure the bending deflection and to observe the damage morphologies.By the FEA approach,a micro-structural unit-cell model of the 3DAWC was established at the yarn level to simulate the fatigue damage.The stress degradation at the loading condition of constant deformation amplitude was calculated to show the degradation of mechanical properties.In addition,the stress distribution,fatigue damage evolution and critical damage regions were also obtained to qualitatively reveal the structural effects and damage mechanisms of the 3DAWC subjected to three-point bending cyclic loading.展开更多
基金National Natural Science Foundation of China(No.51875099)。
文摘Electrical-mechanical coupling behaviors and thermal-resistance effects of 3D braided composites under external loads are important for structural health monitoring(SHM). Electrical conductivity and electrical-mechanical coupling behaviors of 3D braided carbon fiber/epoxy composites under uniaxial tension were reported. It was found that the transverse resistance decreased and the axial resistance increased with the increasing braiding angle. The fractional change in resistance increased linearly as the strain was below 1.0%, and the nonlinearity appeared when the strain exceeded 1.0%. The negative temperature coefficient(NTC) effect was observed before the glass transition temperature Tg of epoxy resin, while there was a positive temperature coefficient(PTC) effect after Tg.
基金National Natural Science Foundation of China(No.51875099)。
文摘Polymer matrix types of fiber hybrid composites are key factors to improve ballistic impact damage tolerances.Here we report ballistic penetration damages of Kevlar/ultra-high molecular weight polyethylene(UHMWPE)hybrid composites with thermoplastic polyurethane(PU)matrix.The hybrid composites were penetrated by fragment-simulating projectiles(FSPs)using an air gun impact system.The effects of stacking sequences on the ballistic performance of hybrid composites were analyzed.Two types of specific energy absorption(the energy absorption per unit area density and the energy absorption per unit thickness)were investigated.It was found that the main damage modes of PU hybrid composites were fiber breakage,matrix damage,fiber pullout and interlayer delamination.The instantaneous deformation could not be used as a reference index for evaluating the ballistic performance of the target plate.The energy absorption process of the PU hybrid composites showed a nonlinear pattern.The hybrid structure affected the specific energy absorption of the materials.
基金supported by the National Natural Science Foundation of China(Grant Nos.11072058 and 11272087)the Foundation for the Author of National Excellent Doctoral Dissertation of China(Grant No.201056)+2 种基金Shanghai Rising-Star Program(Grant No.11QH1400100)the Fundamental Research Funds for the Central Universities of ChinaSpecial Excellent Ph.D International Visit Program by Donghua University(Grant No.102552011003)
文摘This paper reports the structural effects of three-dimensional(3-D)angle-interlock woven composite(3DAWC)undergoing three-point bending cyclic loading from experimental and finite element analysis(FEA)approaches.In experiment,the fatigue tests were conducted to measure the bending deflection and to observe the damage morphologies.By the FEA approach,a micro-structural unit-cell model of the 3DAWC was established at the yarn level to simulate the fatigue damage.The stress degradation at the loading condition of constant deformation amplitude was calculated to show the degradation of mechanical properties.In addition,the stress distribution,fatigue damage evolution and critical damage regions were also obtained to qualitatively reveal the structural effects and damage mechanisms of the 3DAWC subjected to three-point bending cyclic loading.
