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
A modified Swift type flow stress—strain relation was presented in order to describe the uniaxial tension test curve reasonably. The FLD-strain （forming limit diagram made up of limit strain） of 5754O aluminum allo...A modified Swift type flow stress—strain relation was presented in order to describe the uniaxial tension test curve reasonably. The FLD-strain （forming limit diagram made up of limit strain） of 5754O aluminum alloy sheet was calculated based on the two flow stress—strain relations using Yld2000-2d yield function. By comparing the theoretical and experimental results, it is found that the calculated FLD-strain based on the modified Swift flow stress—strain relation can reasonably describe the experimental results. However, though the common Voce flow stress—strain relation can describe the deformation behavior during homogenous deformation phase accurately, the FLD-strain calculated based on it is obviously lower than the experimental result. It is concluded that the higher the hardening rate of sheet metal is, the higher the forming limit is. A method for determining the reasonable flow stress—strain relation is recommended for describing the material behavior during inhomogenous phase and the forming limit of sheet metal.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。
基金Project(51005010)supported by the National Natural Science Foundation of China
文摘A modified Swift type flow stress—strain relation was presented in order to describe the uniaxial tension test curve reasonably. The FLD-strain （forming limit diagram made up of limit strain） of 5754O aluminum alloy sheet was calculated based on the two flow stress—strain relations using Yld2000-2d yield function. By comparing the theoretical and experimental results, it is found that the calculated FLD-strain based on the modified Swift flow stress—strain relation can reasonably describe the experimental results. However, though the common Voce flow stress—strain relation can describe the deformation behavior during homogenous deformation phase accurately, the FLD-strain calculated based on it is obviously lower than the experimental result. It is concluded that the higher the hardening rate of sheet metal is, the higher the forming limit is. A method for determining the reasonable flow stress—strain relation is recommended for describing the material behavior during inhomogenous phase and the forming limit of sheet metal.
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.
