基于形状记忆合金(Shape Memory Alloy,简称SMA)的优良特性,以及其在结构振动控制、减震隔震中的应用,针对2 mm SMA丝进行了力学性能试验。通过改变2 mm SMA丝的循环次数、加载速率、加载幅值等参数,探究2 mm SMA丝各相变应力、等效阻...基于形状记忆合金(Shape Memory Alloy,简称SMA)的优良特性,以及其在结构振动控制、减震隔震中的应用,针对2 mm SMA丝进行了力学性能试验。通过改变2 mm SMA丝的循环次数、加载速率、加载幅值等参数,探究2 mm SMA丝各相变应力、等效阻尼比、单圈循环耗能、残余应变、极限应力应变等力学性能的变化情况。试验表明:循环次数和加载幅值是影响2 mm SMA丝力学性能的主要参数,随着循环次数的增加,2 mm SMA丝的各项力学性能不断降低,最后趋于稳定状态;随着幅值的增加,单圈循环耗能增幅最大,耗能能力不断增强;2 mm SMA丝的极限应力-应变曲线与经典应力-应变曲线的加载段基本吻合。展开更多
Mine overburden dumps have posed significant safety issues in the operations of various unit operations of open pit min-ing especially the external dumps. The external dumps are composed of a mixture of fragmented roc...Mine overburden dumps have posed significant safety issues in the operations of various unit operations of open pit min-ing especially the external dumps. The external dumps are composed of a mixture of fragmented rocks and loose soil. Their charac-teristic is comparable to heavily discontinuous solid mass. The conventional approach of limit equilibrium methods provide safety factors for the slope but nothing about the stress-strain characteristics of the large dump mass. The designs of dump location and their respective geometry are integrated for the know-how of the stability characteristics of these dumps. The discrete element method uses a circular disk to represent the granular solid mass and their interactions are described by the Newton’s third law of motion. The displacement is described by the sliding of the circular disk. This work is focused on the modeling efficiency of the discrete element methods to represent the behaviour of mine dump masses with the specified joint plane for the limit equilibrium method. The advantage of the work lies on the ease of information retrieval at any point at the dump mass concerning the stress and strain histories, displacement, failures etc. which when integrated produces a better understanding of the stability of the dump masses.展开更多
We proposed a bilinearity constitutive curve model of fiber reinforced polymer(FRP) confined concrete which includes a parabola in the first stage and a straight line in the second stage. The FRP-confined concrete has...We proposed a bilinearity constitutive curve model of fiber reinforced polymer(FRP) confined concrete which includes a parabola in the first stage and a straight line in the second stage. The FRP-confined concrete has powerful confinement status and weak confinement status leading to different equations of parabola. We analyzed the impacts of factors such as confinement ratio and restrain stiffness on confined concrete compressive strength,ultimate strain and other control parameters through finite element analysis. The results show that the confinement ratio determines the confinement status,and the increase of the confinement ratio has a limited capacity to increase the compressive strength. The deformation of confined concrete is influenced by restrain stiffness. The stronger the restrain stiffness is,the less the lateral deformation is and the greater ultimate axial strain will be. The consideration of equivalent section coefficient kse is needed in the non-circular section confined concrete. We analyzed the results and proposed boundary values of strong and weak confinement styles,a peak/inflection point stress and strain model,and a compressive strength and ultimate strain model.展开更多
文摘基于形状记忆合金(Shape Memory Alloy,简称SMA)的优良特性,以及其在结构振动控制、减震隔震中的应用,针对2 mm SMA丝进行了力学性能试验。通过改变2 mm SMA丝的循环次数、加载速率、加载幅值等参数,探究2 mm SMA丝各相变应力、等效阻尼比、单圈循环耗能、残余应变、极限应力应变等力学性能的变化情况。试验表明:循环次数和加载幅值是影响2 mm SMA丝力学性能的主要参数,随着循环次数的增加,2 mm SMA丝的各项力学性能不断降低,最后趋于稳定状态;随着幅值的增加,单圈循环耗能增幅最大,耗能能力不断增强;2 mm SMA丝的极限应力-应变曲线与经典应力-应变曲线的加载段基本吻合。
文摘Mine overburden dumps have posed significant safety issues in the operations of various unit operations of open pit min-ing especially the external dumps. The external dumps are composed of a mixture of fragmented rocks and loose soil. Their charac-teristic is comparable to heavily discontinuous solid mass. The conventional approach of limit equilibrium methods provide safety factors for the slope but nothing about the stress-strain characteristics of the large dump mass. The designs of dump location and their respective geometry are integrated for the know-how of the stability characteristics of these dumps. The discrete element method uses a circular disk to represent the granular solid mass and their interactions are described by the Newton’s third law of motion. The displacement is described by the sliding of the circular disk. This work is focused on the modeling efficiency of the discrete element methods to represent the behaviour of mine dump masses with the specified joint plane for the limit equilibrium method. The advantage of the work lies on the ease of information retrieval at any point at the dump mass concerning the stress and strain histories, displacement, failures etc. which when integrated produces a better understanding of the stability of the dump masses.
基金Funded by the Science and Technology Plan Project (No. 62065) of Guangzhou.
文摘We proposed a bilinearity constitutive curve model of fiber reinforced polymer(FRP) confined concrete which includes a parabola in the first stage and a straight line in the second stage. The FRP-confined concrete has powerful confinement status and weak confinement status leading to different equations of parabola. We analyzed the impacts of factors such as confinement ratio and restrain stiffness on confined concrete compressive strength,ultimate strain and other control parameters through finite element analysis. The results show that the confinement ratio determines the confinement status,and the increase of the confinement ratio has a limited capacity to increase the compressive strength. The deformation of confined concrete is influenced by restrain stiffness. The stronger the restrain stiffness is,the less the lateral deformation is and the greater ultimate axial strain will be. The consideration of equivalent section coefficient kse is needed in the non-circular section confined concrete. We analyzed the results and proposed boundary values of strong and weak confinement styles,a peak/inflection point stress and strain model,and a compressive strength and ultimate strain model.