The indentation technique is widely used in measuring the mechanical properties of soft matter at the microscale or nanoscale,but still faces challenges by these unique properties as well as the consequent strong surf...The indentation technique is widely used in measuring the mechanical properties of soft matter at the microscale or nanoscale,but still faces challenges by these unique properties as well as the consequent strong surface adhesion, including the strong nonlinear effect, unclear judgment of the contact point, difficulties in estimating the contact area, and the risk of the indenter piercing the sample. Here we propose a two-step method to solve these problems: lay a hard film on a soft matter, and obtain the viscoelastic properties of this soft matter through the indentation response of this composite structure. We first establish a theoretical indentation model of the hard film-soft substrate system based on the theory of plates, elastic-viscoelastic correspondence principle and Boltzmann superposition principle. To verify the correctness of this method, we measure the mechanical properties of the methyl vinyl silicone rubber(MVSR) covered by a Cu nanofilm. Finally, we test the effectiveness and error sensitivity of this method with the finite element method(FEM). The results show that our method can accurately measure the mechanical properties of soft matter, while effectively circumventing the problems of the traditional indentation technique.展开更多
目的探索基于原子力显微镜(atomic force microscope,AFM)压痕技术确定大鼠小梁网组织弹性模量的方法,为揭示小梁网组织力学特性与小梁网通道房水外流阻力之间的关系等研究奠定基础。方法首先利用大鼠眼球组织切片获取大鼠小梁网组织与...目的探索基于原子力显微镜(atomic force microscope,AFM)压痕技术确定大鼠小梁网组织弹性模量的方法,为揭示小梁网组织力学特性与小梁网通道房水外流阻力之间的关系等研究奠定基础。方法首先利用大鼠眼球组织切片获取大鼠小梁网组织与毗邻组织之间的距离信息和结构信息;其次利用AFM压痕实验获取角膜-角巩膜缘-小梁网-巩膜方向的弹性模量与相对位置的关系;最后综合对比以确定小梁网组织测试区域。结果探索了一种基于原子力显微镜压痕实验定位小梁网组织并获取该组织弹性模量的方法,利用该方法获取了大鼠眼球鼻侧、颞侧、上侧、下侧4个位置处的小梁网组织弹性模量范围为300~600 Pa。结论本研究给出了一种基于AFM压痕技术确定大鼠小梁网组织弹性模量的方法,该方法提供了AFM测试环境下小梁网组织区域的位置参考,优势在于可快速定位到大鼠小梁网组织区域。展开更多
Cast irons with some kinds of cementite with different chromium and vanadium contents were character- ized. Fracture toughness was determined by using an indentation technique, along with microhardness and elastic mod...Cast irons with some kinds of cementite with different chromium and vanadium contents were character- ized. Fracture toughness was determined by using an indentation technique, along with microhardness and elastic modulus. The results show that at the load of 1 N, microhardness of the cementite with 5.1% Cr is 10.53 GPa, the microhardness for cementite with 9.2% Cr increased to 11.25 GPa and for cementite with 4.5% V the microhard- ness is 9.18 GPa. The cementite with 9.2% Cr presented the highest elastic modulus of 230.4 GPa and the cement- ire with 4% V presented the lowest value of 201.32 GPa. Cementite with 5.1% Cr presented higher fracture tough- ness than cementite with 9.2% Cr; however, cementite with 4.5% V presented the highest fracture toughness of 2.74 MPa ·m1/2 and the lowest brittleness index of 3.35 μm-1/2.展开更多
基金the National Natural Science Foundation of China(Grant Nos.11432014,11521202,11672301,and 11890681).
文摘The indentation technique is widely used in measuring the mechanical properties of soft matter at the microscale or nanoscale,but still faces challenges by these unique properties as well as the consequent strong surface adhesion, including the strong nonlinear effect, unclear judgment of the contact point, difficulties in estimating the contact area, and the risk of the indenter piercing the sample. Here we propose a two-step method to solve these problems: lay a hard film on a soft matter, and obtain the viscoelastic properties of this soft matter through the indentation response of this composite structure. We first establish a theoretical indentation model of the hard film-soft substrate system based on the theory of plates, elastic-viscoelastic correspondence principle and Boltzmann superposition principle. To verify the correctness of this method, we measure the mechanical properties of the methyl vinyl silicone rubber(MVSR) covered by a Cu nanofilm. Finally, we test the effectiveness and error sensitivity of this method with the finite element method(FEM). The results show that our method can accurately measure the mechanical properties of soft matter, while effectively circumventing the problems of the traditional indentation technique.
文摘目的探索基于原子力显微镜(atomic force microscope,AFM)压痕技术确定大鼠小梁网组织弹性模量的方法,为揭示小梁网组织力学特性与小梁网通道房水外流阻力之间的关系等研究奠定基础。方法首先利用大鼠眼球组织切片获取大鼠小梁网组织与毗邻组织之间的距离信息和结构信息;其次利用AFM压痕实验获取角膜-角巩膜缘-小梁网-巩膜方向的弹性模量与相对位置的关系;最后综合对比以确定小梁网组织测试区域。结果探索了一种基于原子力显微镜压痕实验定位小梁网组织并获取该组织弹性模量的方法,利用该方法获取了大鼠眼球鼻侧、颞侧、上侧、下侧4个位置处的小梁网组织弹性模量范围为300~600 Pa。结论本研究给出了一种基于AFM压痕技术确定大鼠小梁网组织弹性模量的方法,该方法提供了AFM测试环境下小梁网组织区域的位置参考,优势在于可快速定位到大鼠小梁网组织区域。
文摘Cast irons with some kinds of cementite with different chromium and vanadium contents were character- ized. Fracture toughness was determined by using an indentation technique, along with microhardness and elastic modulus. The results show that at the load of 1 N, microhardness of the cementite with 5.1% Cr is 10.53 GPa, the microhardness for cementite with 9.2% Cr increased to 11.25 GPa and for cementite with 4.5% V the microhard- ness is 9.18 GPa. The cementite with 9.2% Cr presented the highest elastic modulus of 230.4 GPa and the cement- ire with 4% V presented the lowest value of 201.32 GPa. Cementite with 5.1% Cr presented higher fracture tough- ness than cementite with 9.2% Cr; however, cementite with 4.5% V presented the highest fracture toughness of 2.74 MPa ·m1/2 and the lowest brittleness index of 3.35 μm-1/2.
