Materials with the same elastic modulus E and representative stress and strain （σr,εr） present similar indentation-loading curves, whatever the value of strain hardening exponent n. Based on this definition, a goo...Materials with the same elastic modulus E and representative stress and strain （σr,εr） present similar indentation-loading curves, whatever the value of strain hardening exponent n. Based on this definition, a good approach was proposed to extract the plastic properties or constitutive equations of metals from nanoindentation test combining finite element simulation. Firstly, without consideration of strain hardening, the representative stress was determined by varying assumed representative stress over a wide range until a good agreement was reached between the computed and experimental loading curves. Similarly, the corresponding representative strain was determined with different hypothetical values of strain hardening exponent in the range of 0-0.6. Through modulating assumed strain hardening exponent values to make the computed unloading curve coincide with that of the experiment, the real strain hardening exponent was acquired. Once the strain hardening exponent was determined, the initial yield stress ay of metals could be obtained by the power law constitution. The validity of the proposed methodology was verified by three real metals： AISI 304 steel, Fe andA1 alloy.展开更多
通过对平纹编织C/SiC复合材料经向和纬向截面的扫描电子显微镜(Scanning Electron Microscope,SEM)照片的精确测量,获取了纤维束的几何参数和波动曲线,以四参数正弦函数为拟合函数,得到了纤维束纵、横截面的参数化曲线方程。并通过建立...通过对平纹编织C/SiC复合材料经向和纬向截面的扫描电子显微镜(Scanning Electron Microscope,SEM)照片的精确测量,获取了纤维束的几何参数和波动曲线,以四参数正弦函数为拟合函数,得到了纤维束纵、横截面的参数化曲线方程。并通过建立的代表特征体元(representative volume element,RVE)得到纤维体积含量的计算值与试验测定值相比较,来检验模型的精确性。以MSC.PATRAN为平台,采用六面体单元进行分网,得到了RVE的三维有限元模型。通过在RVE模型中预制孔洞的方法,计算了平纹编织C/SiC复合材料的有效弹性模量,其中轴向拉伸模量与轴向剪切模量的计算值与试验值吻合较好,其它3个有效弹性模量还有待试验值的检验。展开更多
A structural composite is a material system consisting of two or more phases on a macroscopic scale, whose mechanical performance and properties are designed to be superior to those of constituent materials acting ind...A structural composite is a material system consisting of two or more phases on a macroscopic scale, whose mechanical performance and properties are designed to be superior to those of constituent materials acting independently. Fiber reinforced composites (FRP) are slowly emerging from the realm of advanced materials and are replacing conventional materials in a variety of applications. However, the mechanics of FRPs are complex owing to their anisotropic and heterogeneous characteristics. In this paper a representative volume model has been considered and a finite element model incorporating the necessary boundary conditions is developed using available FEA package ANSYS to predict the elastic property of the composite. For verification, the numerical results of elastic properties are compared with the analytical solution and it is found that there is a good agreement between these results.展开更多
基金Project （51171125） supported by the National Natural Science Foundation of China Project （20110321051 ） supported by the Science and Technology Key Project of Shanxi Province, China
文摘Materials with the same elastic modulus E and representative stress and strain （σr,εr） present similar indentation-loading curves, whatever the value of strain hardening exponent n. Based on this definition, a good approach was proposed to extract the plastic properties or constitutive equations of metals from nanoindentation test combining finite element simulation. Firstly, without consideration of strain hardening, the representative stress was determined by varying assumed representative stress over a wide range until a good agreement was reached between the computed and experimental loading curves. Similarly, the corresponding representative strain was determined with different hypothetical values of strain hardening exponent in the range of 0-0.6. Through modulating assumed strain hardening exponent values to make the computed unloading curve coincide with that of the experiment, the real strain hardening exponent was acquired. Once the strain hardening exponent was determined, the initial yield stress ay of metals could be obtained by the power law constitution. The validity of the proposed methodology was verified by three real metals： AISI 304 steel, Fe andA1 alloy.
文摘通过对平纹编织C/SiC复合材料经向和纬向截面的扫描电子显微镜(Scanning Electron Microscope,SEM)照片的精确测量,获取了纤维束的几何参数和波动曲线,以四参数正弦函数为拟合函数,得到了纤维束纵、横截面的参数化曲线方程。并通过建立的代表特征体元(representative volume element,RVE)得到纤维体积含量的计算值与试验测定值相比较,来检验模型的精确性。以MSC.PATRAN为平台,采用六面体单元进行分网,得到了RVE的三维有限元模型。通过在RVE模型中预制孔洞的方法,计算了平纹编织C/SiC复合材料的有效弹性模量,其中轴向拉伸模量与轴向剪切模量的计算值与试验值吻合较好,其它3个有效弹性模量还有待试验值的检验。
文摘A structural composite is a material system consisting of two or more phases on a macroscopic scale, whose mechanical performance and properties are designed to be superior to those of constituent materials acting independently. Fiber reinforced composites (FRP) are slowly emerging from the realm of advanced materials and are replacing conventional materials in a variety of applications. However, the mechanics of FRPs are complex owing to their anisotropic and heterogeneous characteristics. In this paper a representative volume model has been considered and a finite element model incorporating the necessary boundary conditions is developed using available FEA package ANSYS to predict the elastic property of the composite. For verification, the numerical results of elastic properties are compared with the analytical solution and it is found that there is a good agreement between these results.
