The two-parameter Weibull model is used to describe the fiber strength distribution.The stress carried by the intact and fracture fibers on the matrix crack plane during unloading/reloading is determined based on the ...The two-parameter Weibull model is used to describe the fiber strength distribution.The stress carried by the intact and fracture fibers on the matrix crack plane during unloading/reloading is determined based on the global load sharing criterion.The axial stress distribution of intact fibers upon unloading and reloading is determined based on the mechanisms of fiber sliding relative to matrix in the interface debonded region.The interface debonded length,unloading interface counter slip length,and reloading interface new slip length are obtained by the fracture mechanics approach.The hysteresis loops corresponding to different stresses considering fiber failure are compared with the cases without considering fiber failure.The effects of fiber characteristic strength and fiber Weibull modulus on the fiber failure,the shape,and the area of the hysteresis loops are analyzed.The predicted quasi-static unloading/reloading hysteresis loops agree well with experimental data.展开更多
A shear-lag model is applied to study the stress transfer around a broken fiber within unidirectional fiber-reinforced composites(FRC) subjected to uniaxial tensile loading along the fiber direction.The matrix damage ...A shear-lag model is applied to study the stress transfer around a broken fiber within unidirectional fiber-reinforced composites(FRC) subjected to uniaxial tensile loading along the fiber direction.The matrix damage and interfacial debonding,which are the main failure modes,are considered in the model.The maximum stress criterion with the linear damage evolution theory is used for the matrix.The slipping friction stress is considered in the interfacial debonding region using Coulomb friction theory,in which interfacial clamping stress comes from radial residual stress and mismatch of Poisson's ratios of constituents(fiber and matrix).The stress distributions in the fiber and matrix are obtained by the shear-lag theory added with boundary conditions,which includes force continuity and displacement compatibility constraints in the broken and neighboring intact fibers.The result gives axial stress distribution in fibers and shear stress in the interface and compares the theory reasonably well with the measurement by a polarized light microscope.The relation curves between damage,debonding and ineffective region lengths with external strain loading are obtained.展开更多
基金Supported by the National Natural Science Foundation of China(51075204)the Graduate Innovation Foundation of Jiangsu Province(CX08B-133Z)the Doctoral Innovation Foundation of Nanjing University of Aeronautics and Astronautics(BCXJ08-05)~~
文摘The two-parameter Weibull model is used to describe the fiber strength distribution.The stress carried by the intact and fracture fibers on the matrix crack plane during unloading/reloading is determined based on the global load sharing criterion.The axial stress distribution of intact fibers upon unloading and reloading is determined based on the mechanisms of fiber sliding relative to matrix in the interface debonded region.The interface debonded length,unloading interface counter slip length,and reloading interface new slip length are obtained by the fracture mechanics approach.The hysteresis loops corresponding to different stresses considering fiber failure are compared with the cases without considering fiber failure.The effects of fiber characteristic strength and fiber Weibull modulus on the fiber failure,the shape,and the area of the hysteresis loops are analyzed.The predicted quasi-static unloading/reloading hysteresis loops agree well with experimental data.
文摘A shear-lag model is applied to study the stress transfer around a broken fiber within unidirectional fiber-reinforced composites(FRC) subjected to uniaxial tensile loading along the fiber direction.The matrix damage and interfacial debonding,which are the main failure modes,are considered in the model.The maximum stress criterion with the linear damage evolution theory is used for the matrix.The slipping friction stress is considered in the interfacial debonding region using Coulomb friction theory,in which interfacial clamping stress comes from radial residual stress and mismatch of Poisson's ratios of constituents(fiber and matrix).The stress distributions in the fiber and matrix are obtained by the shear-lag theory added with boundary conditions,which includes force continuity and displacement compatibility constraints in the broken and neighboring intact fibers.The result gives axial stress distribution in fibers and shear stress in the interface and compares the theory reasonably well with the measurement by a polarized light microscope.The relation curves between damage,debonding and ineffective region lengths with external strain loading are obtained.
