Indenter–Foam Dampers Inspired by Cartilage: Dynamic Mechanical Analyses and Design

Abstract

Articular cartilage is a thin layer of a solid matrix swollen by fluid, and it protects joints from damage via poroviscoelastic damping. Our previous experimental and simulation studies showed that cartilage-like poroviscoelastic damping could widen the range of damping methods in a low-frequency range (<100 Hz). Thus, the current study aimed to realize cartilage-like damping capacity by single- and two-indenter–foam poroviscoelastic dampers in a low-frequency range. Multiple single-indenter–foam dampers were designed by combining foam sheets with different pore diameters and indenters with different radii. Their damping capacity was investigated by dynamic mechanical analysis in a frequency range of 0.5–100 Hz. Single-indenter–foam dampers delivered peak damping frequencies that depended on the foam’s pore diameter and characteristic diffusion length (contact radii). Those dampers maximize the damping capacity at the desired frequency (narrowband performance). A mechanical model combined with simple scaling laws was shown to relate poroelasticity to the peak damping frequencies reasonably well. Finally, combinations of single-indenter–foam dampers were optimized to obtain a two-indenter–foam damper that delivered nearly rate-independent damping capacity within 0.5–100 Hz (broadband performance). These findings suggested that cartilage-like poroviscoelastic dampers can be an effective mean of passive damping for narrowband and broadband applications.

Characterization of drying-induced changes in moduli and internal stresses in a constrained gel using laser vibrometry

“…Vibration and wave-based characterization offers a viable alternative for soft materials. [20][21][22][23][24][25][26] For instance, laser vibrometry 21 is shown to characterize dynamic and viscoelastic properties of multiphasic biological tissues such as cartilage considerably faster than conventional techniques. 21 Studies utilized vibration techniques to understand parametric resonances in soft materials and water droplets; 27 develop variable stiffness artificial muscles for vibration absorption; 28 and achieve broadband vibration attenuation using soft materials.…”