A damage detection method for complicated beam-like structures is proposed based on the subsection strain energy method (SSEM), and its applicability condition is introduced. For a beam with the continuously varying...A damage detection method for complicated beam-like structures is proposed based on the subsection strain energy method (SSEM), and its applicability condition is introduced. For a beam with the continuously varying fiexural stiffness and an edge crack, the SSEM is used to detect the crack location effectively by numerical modal shapes. As a complicated beam, the glass fiber-reinforced composite model of a wind turbine blade is studied based on an experimental modal analysis. The SSEM is used to calculate the damage index from the measured modal parameters and locate the damage position in the blade model successfully. The results indicate that the SSEM based on the modal shapes can be used to detect the damages in complicated beams or beam-like structures for engineering applications.展开更多
On the base of controllable variable stiffness property,variable stiffness composites were the main components of functional materials in aerospace.However,the relatively low mechanical strength,stiffness range,and re...On the base of controllable variable stiffness property,variable stiffness composites were the main components of functional materials in aerospace.However,the relatively low mechanical strength,stiffness range,and response rate restricted the application of variable stiffness composite.In this work,the novel variable stiffness composite system with characteristics of repeatable high load bearing and response rate was successfully prepared via the double-layer anisotropic structure to solve the bottlenecks of variable stiffness composites.The novel variable stiffness composite systems were composed of variable stiffness layer of polycaprolactone(PCL)and the driven layer of silicone elastomer with alcohol,which continuously changed Young’s modulus from 0.1 to 7.263 MPa(72.63 times variation)in 200 s and maintained maximum weight of 11.52 times its own weight(8.5 g).Attributed to the relatively high variable stiffness range and load bearing value of variable stiffness composite system,the repeatable response process led to the efficient high load driven as“muscle”and diversified precise grab of objects with different shapes as“gripper”,owning widespread application prospects in the field of bionics.展开更多
A novel canonical Euler splitting method is proposed for nonlinear compositestiff functional differential-algebraic equations, the stability and convergence of themethod is evidenced, theoretical results are further c...A novel canonical Euler splitting method is proposed for nonlinear compositestiff functional differential-algebraic equations, the stability and convergence of themethod is evidenced, theoretical results are further confirmed by some numerical experiments.Especially, the numerical method and its theories can be applied to specialcases, such as delay differential-algebraic equations and integral differential-algebraicequations.展开更多
This paper presents the results of an experimental research on reinforced concrete beams strengthened with an external carbon fibre reinforced polymer(CFRP) layer under long-term load action that lasted for 330 d.We d...This paper presents the results of an experimental research on reinforced concrete beams strengthened with an external carbon fibre reinforced polymer(CFRP) layer under long-term load action that lasted for 330 d.We describe the characteristics of deflection development of the beams strengthened with different additional anchorages of the external carbon fibre composite layer during the period of interest.The conducted experiments showed that the additional anchorage influences the slip of the external layer with respect to the strengthened element.Thus,concrete and carbon fibre composite interface stiffness decreases with a long-term load action.Therefore,the proposed method of analysis based on the built-up-bars theory can be used to estimate concrete and carbon fibre composite interface stiffness in the case of long-term load.展开更多
基金supported by the National Basic Research Program of China (973 Program)(No. 2007CB714603)
文摘A damage detection method for complicated beam-like structures is proposed based on the subsection strain energy method (SSEM), and its applicability condition is introduced. For a beam with the continuously varying fiexural stiffness and an edge crack, the SSEM is used to detect the crack location effectively by numerical modal shapes. As a complicated beam, the glass fiber-reinforced composite model of a wind turbine blade is studied based on an experimental modal analysis. The SSEM is used to calculate the damage index from the measured modal parameters and locate the damage position in the blade model successfully. The results indicate that the SSEM based on the modal shapes can be used to detect the damages in complicated beams or beam-like structures for engineering applications.
基金the project of the National Key Research and Development Program of China(2018YFA0703300)the National Natural Science Foundation of China(52105302,52175271,52021003,and 91848204)+1 种基金the team of Innovation and entrepreneurship of Jilin Province(20210509047RQ,20210508057RQ)the Program for JLU Science and Technology Innovative Research Team(2017TD-04).
文摘On the base of controllable variable stiffness property,variable stiffness composites were the main components of functional materials in aerospace.However,the relatively low mechanical strength,stiffness range,and response rate restricted the application of variable stiffness composite.In this work,the novel variable stiffness composite system with characteristics of repeatable high load bearing and response rate was successfully prepared via the double-layer anisotropic structure to solve the bottlenecks of variable stiffness composites.The novel variable stiffness composite systems were composed of variable stiffness layer of polycaprolactone(PCL)and the driven layer of silicone elastomer with alcohol,which continuously changed Young’s modulus from 0.1 to 7.263 MPa(72.63 times variation)in 200 s and maintained maximum weight of 11.52 times its own weight(8.5 g).Attributed to the relatively high variable stiffness range and load bearing value of variable stiffness composite system,the repeatable response process led to the efficient high load driven as“muscle”and diversified precise grab of objects with different shapes as“gripper”,owning widespread application prospects in the field of bionics.
基金National Natural Science Foundation of China(Grant No.11971412)Key Project of Education Department of Hunan Province(Grant No.20A484)Project of Hunan National Center for Applied Mathematics(Grant No.2020ZYT003).
文摘A novel canonical Euler splitting method is proposed for nonlinear compositestiff functional differential-algebraic equations, the stability and convergence of themethod is evidenced, theoretical results are further confirmed by some numerical experiments.Especially, the numerical method and its theories can be applied to specialcases, such as delay differential-algebraic equations and integral differential-algebraicequations.
文摘This paper presents the results of an experimental research on reinforced concrete beams strengthened with an external carbon fibre reinforced polymer(CFRP) layer under long-term load action that lasted for 330 d.We describe the characteristics of deflection development of the beams strengthened with different additional anchorages of the external carbon fibre composite layer during the period of interest.The conducted experiments showed that the additional anchorage influences the slip of the external layer with respect to the strengthened element.Thus,concrete and carbon fibre composite interface stiffness decreases with a long-term load action.Therefore,the proposed method of analysis based on the built-up-bars theory can be used to estimate concrete and carbon fibre composite interface stiffness in the case of long-term load.