Elastic memory composites （EMCs） have great potential applications in future deployable space structures due to their high packaging strain and shape memory characteristics. Microbuckling of compressed fibers is the...Elastic memory composites （EMCs） have great potential applications in future deployable space structures due to their high packaging strain and shape memory characteristics. Microbuckling of compressed fibers is the primary deformation mechanism of such structures to receive a higher packaging strain than that of traditional fiber-reinforced composites. In order to have a better understanding of such deformation mechanism, the microbuckling model of EMC laminates under bending is analyzed firstly. Then the theoretical critical microbuckling parameters are predicted, which are compared with experimental observations and other models.展开更多
A two-dimensional linear spring model is established to study the microbuckling of a plane monomolecular layer adhering to a substrate. The model is for the layer subjected to a compressive load having an arbitrary an...A two-dimensional linear spring model is established to study the microbuckling of a plane monomolecular layer adhering to a substrate. The model is for the layer subjected to a compressive load having an arbitrary angle with the chemical bond of the layer. The effects of the load angle, the strength of adhesion and the bending stiffness and shearing stiffness (the capability of resisting transverse bending and in-plane shearing) of the layer on the minimal buckling force and the critical buckling mode are discussed. It is found that the minimal buckling force increases with increasing load angle and, for a given bending stiffness, increases with increasing strength of adhesion and decreasing shearing stiffness. Furthermore, a critical condition under which the buckling of the layer can just occur is obtained, which is helpful to avoid buckling in an engineering application.展开更多
Two grades of Dyneema composite laminates with the commercial designations of HB26 and HB50 were cut into blocks with or without an edge crack and compressed in the lon- gitudinal fiber direction. The cracked and uncr...Two grades of Dyneema composite laminates with the commercial designations of HB26 and HB50 were cut into blocks with or without an edge crack and compressed in the lon- gitudinal fiber direction. The cracked and uncracked specimens show similar compressive responses including failure pattern and failure load. The two grades of Dyneema composites exhibits different failure modes： a diffuse, sinusoidal buckling pattern for Dyneema HB50 due to its weak matrix constituent and a kink band for Dyneema~ HB26 due to its relatively stronger matrix constituent. An effective finite element model is used to simulate the collapse of Dyneema composites, and the sensitivity of laminate compressive responses to the overall effective shear modulus, interlaminar shear strength, thickness and imperfection angle are investigated. The change of failure mode from kink band to sinusoidal buckling pattern by decreasing the interlaminar shear strength is validated by the finite element analyses.展开更多
基金supported by the National Natural Science Foundation of China (Nos.10872025 and 10632020)the Ministry of Education of the People’s Republic of China (NECT)
文摘Elastic memory composites （EMCs） have great potential applications in future deployable space structures due to their high packaging strain and shape memory characteristics. Microbuckling of compressed fibers is the primary deformation mechanism of such structures to receive a higher packaging strain than that of traditional fiber-reinforced composites. In order to have a better understanding of such deformation mechanism, the microbuckling model of EMC laminates under bending is analyzed firstly. Then the theoretical critical microbuckling parameters are predicted, which are compared with experimental observations and other models.
基金The project supported by the National Distinguished Young Scientist Fund Cheung Kong Scholars Programme+1 种基金the National Natural Science Foundation of China (10272082, 10172068)Shanghai Post-doctoral Science Foundation
文摘A two-dimensional linear spring model is established to study the microbuckling of a plane monomolecular layer adhering to a substrate. The model is for the layer subjected to a compressive load having an arbitrary angle with the chemical bond of the layer. The effects of the load angle, the strength of adhesion and the bending stiffness and shearing stiffness (the capability of resisting transverse bending and in-plane shearing) of the layer on the minimal buckling force and the critical buckling mode are discussed. It is found that the minimal buckling force increases with increasing load angle and, for a given bending stiffness, increases with increasing strength of adhesion and decreasing shearing stiffness. Furthermore, a critical condition under which the buckling of the layer can just occur is obtained, which is helpful to avoid buckling in an engineering application.
基金supported by the National Natural Science Foundation of China (11242015,11172071)
文摘Two grades of Dyneema composite laminates with the commercial designations of HB26 and HB50 were cut into blocks with or without an edge crack and compressed in the lon- gitudinal fiber direction. The cracked and uncracked specimens show similar compressive responses including failure pattern and failure load. The two grades of Dyneema composites exhibits different failure modes： a diffuse, sinusoidal buckling pattern for Dyneema HB50 due to its weak matrix constituent and a kink band for Dyneema~ HB26 due to its relatively stronger matrix constituent. An effective finite element model is used to simulate the collapse of Dyneema composites, and the sensitivity of laminate compressive responses to the overall effective shear modulus, interlaminar shear strength, thickness and imperfection angle are investigated. The change of failure mode from kink band to sinusoidal buckling pattern by decreasing the interlaminar shear strength is validated by the finite element analyses.
