Experimental and Analytical Study on the High Strain Rate Dynamic Mechanical Properties of Single-Crystal Silicon for Representative Crystal Orientations

As the most commonly used substrate material in microelectromechanical systems (MEMS), the quasistatic mechanical properties of single-crystal silicon (SCS) have been widely studied. However, there is a lack of data and insufficient research on its mechanical characteristics under high strain rates, which limits the expansion of silicon-based MEMS applications. Herein, the dynamic mechanical behavior of SCS under high strain rates is investigated using split Hopkinson pressure bar experiments conducted on samples with three different crystal orientations. The results indicate that the ultimate strength of all three crystallographic orientations significantly increases with the strain rate, demonstrating a clear strain rate sensitivity. Among them, the <111> orientation exhibits the highest ultimate strength across all strain rates, while the <100> orientation shows the lowest. Additionally, compared to quasistatic loading, the elastic modulus of SCS experiences a reduction of over 50% at high strain rates. This study offers a basis for future efforts in establishing rate-dependent constitutive models for SCS, optimizing the design of silicon-based MEMS structures, and broadening the application scope of silicon-based MEMS.