多孔棉布-酚醛轴承保持架的应变速率敏感性

为了分析研究多孔棉布-酚醛轴承保持架的应变速率敏感性，使用纳米压痕仪测量其在应变速率为0.01～ 0.05 s?1时的硬度和弹性模量，通过Kelvin-Voigt模型对材料的黏弹性进行分析，研究了材料在不同应变速率下的应变硬化效应和应变局部软化效应. 研究结果表明:随着应变速率提高，多孔棉布-酚醛材料的硬度和弹性模量先增加后减小；当应变速率从0.01 s?1增加到0.05 s?1，多孔棉布-酚醛材料硬度和弹性模量的增加与材料的应变硬化现象有关；当应变速率从0.05 s?1增加到0.30 s?1，蠕变位移显著增加，接触刚度快速降低，形变以热的形式消耗在压头与材料的接触界面，压头接触区材料从黏弹性向黏性转变，局部材料黏度降低，硬度和弹性模量快速减小；多孔棉布-酚醛的硬度和弹性模量随应变速率的变化是应变硬化效应和应变局部软化效应竞争的结果. 

Strain Rate Sensitivity of Porous Cotton-Phenolic Bearing Retainer

In order to study the strain rate sensitivity of porous cotton cloth-phenolic bearing retainer, the hardness and elastic modulus of the porous cotton cloth-phenolic bearing retainer were measured by nanoindenter when the strain rate ranged from 0.01 s?1 to 0.05 s?1. And then the viscoelastic properties of the materials were analyzed by Kelvin-Voigt model. The strain hardening effect and strain local softening effect of the material under different strain rates were studied. The results show that with the increase of strain rate, the hardness and elastic modulus of porous cotton cloth-phenolic material first increase and then decrease. When the strain rate increases from 0.01 s?1 to 0.05 s?1, the increase of hardness and elastic modulus of porous cotton cloth-phenolic material is related to the strain hardening phenomenon of the material. When the strain rate increases from 0.05 s?1 to 0.30 s?1, the creep displacement increases significantly, the contact stiffness decreases rapidly, the deformation is consumed in the contact interface between the indenter and the material in the form of heat, the material in the contact area of the indenter changes from viscoelasticity to viscosity, the local material viscosity decreases, and the hardness and elastic modulus decrease rapidly. The change of hardness and elastic modulus of porous cotton cloth-phenolic aldehyde with strain rate is the result of the competition between strain hardening effect and strain local softening effect.