Nanoindentation was used to investigate the strain rate sensitivity and indentation creep behaviors of aged Polymethyl methacrylate (PMMA). Results show that the change law of strain rate sensitive index is found consistent with $R_{h_{ev}}+R_{h_v}$ vs. aging time. This phenomenon illustrates the strain rate sensitivity of continuum solids results from their inherent time-dependent deformation properties.

中文翻译：

---

老化PMMA压痕应变速率敏感性的研究

纳米压痕用于研究老化的聚甲基丙烯酸甲酯（PMMA）的应变速率敏感性和压痕蠕变行为。结果表明，应变率敏感指数的变化规律与${\mathrm{[R}}_{H_{Ëv}}+{\mathrm{[R}}_{H_v}$与老化时间。这种现象说明了连续体固体固有的随时间变化的变形特性导致的应变率敏感性。