砌浆层状复合材料珍珠层的应变率效应

Effect of strain rate on nacre with brick-and-mortar microstructure

为了分析具有砌浆结构的层状复合材料的应变率效应,以珍珠层为研究对象,采用纳米压入法测试珍珠层力学性能,利用连续刚度测量法得到不同加载速率下材料的硬度值和弹性模量。利用扫描电子显微镜观察珍珠层不同方向的砌浆微结构形貌,并结合微观结构对比分析不同压入深度和不同应变率两种工况下,珍珠层表层与横断面方向的力学性能。结果表明:在相同加载条件下,珍珠层表层方向的弹性模量小于其横断面方向的弹性模量,而表层方向硬度值则大于横断面方向的硬度值;当应变率恒定时,珍珠层弹性模量与硬度随压入深度增加而增加,当压入深度达到750nm后,弹性模量不再随压入深度变化而变化;当压入深度恒定时,硬度值、弹性模量和弹性回复率均随着应变率的增加而变大。

In order to study the strain rate sensitivity of laminate composites with brick-and-mortar microstructure,the mechanical properties of nacre were tested by nanoindentation test system.Continuous stiffness measurement（CSM）technique was adopted to obtain hardness and elastic modulus values under different strain rates.Scanning electron microscope（SEM）was used to observe the microstructure of nacre in different directions.The effects of indentation depths and strain rates on the mechanical properties of nacre both in the surface and the cross-section were investigated.Results show that,under the same loading condition,elastic modulus in the surface is lower than that in the cross-section,but hardness is higher,and under constant strain rate,elastic modulus and hardness of nacre are increased with the increase of indentation,and when indentation reaches 750 nm,the elastic modulus stays unchanged with indentation increasing,while when indentation is a constant,the hardness,elastic modulus and elastic recovery increase with the increase of strain rate.