Experimental Study of Low-Cycle Fatigue and Recovery of Polymer Blends for Viscous Damping Walls

The viscoelastic materials used in traditional viscous damping walls (VDWs) typically exhibit high storage moduli, which tend to exacerbate the structural response of adjacent components during earthquakes. Furthermore, existing studies are mostly limited to small-strain characterization and lack investigation into the macroscopic mechanical recovery characteristics of materials under mainshock-aftershock sequences. To overcome these limitations, this study introduces silicone oil (SO) as a softener to prepare a novel viscoelastic polymer blend (PIB-B12-SO). Utilizing a customized self-stabilization dynamic sandwich-type shear (S-DSTS) device, the macroscopic dynamic mechanical behavior of the blend was systematically evaluated, focusing on its low-cycle fatigue and rest-recovery characteristics. The results indicate that the addition of SO effectively reduces the storage modulus and significantly enhances the loss factor of the blend. Notably, at a mixing ratio of 1:4 (SO: PIB-B12), the loss factor increased by 65.6% compared to pure PIB-B12. Furthermore, the introduction of SO effectively suppresses the degradation of the loss modulus under cyclic loading and promotes viscous recovery during the rest periods. The silicone oil blend modification successfully optimizes the macroscopic viscoelastic properties of PIB-B12, significantly enhancing the energy dissipation stability of the material under low-cycle fatigue and interval loading.