Performance evaluation of friction dampers considering different metal pairs and loading rates

Metal friction dampers are widely applied for structural energy dissipation and shock absorption, and their dynamic performance needs further study. Cyclic loading tests were conducted on 30 specimens to evaluate the effects of loading sequence and rate under high speed (20 mm/s ∼ 60 mm/s) and low speed (0.2 mm/s ∼ 3 mm/s). The friction pairs included five types: brass-hot rolled steel with untreated surfaces (B-HS), brass-hot rolled steel with polished surfaces (B-PHS), brass-stainless steel (B-SS), stainless steel-hot rolled steel with untreated surfaces (SS-HS), and stainless steel-hot rolled steel with polished surfaces (SS-PHS). The test results showed that all specimens exhibited plump rigid-plastic hysteresis behavior under different loading rates, and the mechanical indices of the specimens met the discreteness requirements of FEMA-356. The loading rates obviously influenced the normal force loss and friction coefficient of the friction interfaces. The static friction coefficients for the five metal friction pairs were recommended, and analytical models of the dynamic friction coefficient concerning loading rate were established. It was suggested that the B-HS, B-PHS, SS-HS, and SS-PHS friction pairs should be pre-friction within the travel range before use, and the friction coefficient of the B-SS and SS-HS friction pairs should be calibrated after the first loading.