Study on Damping Capacities of Nodular Cast Iron Dense Bar Produced By Horizontal Continuous Casting

摘要

Damping capacities of the annealed nodular cast iron dense bar produced by horizontal continuous casting were measured by Dynamic Mechanical Analyzer. The relation of damping capacities with vibration amplitude, frequency and temperature was analyzed to investigate the damping mechanism of the alloy. The results show that the damping capacities increase with increasing temperature and frequency. The internal friction spectra exhibits two internal friction peaks at about 40°C and 150°C and caused by Snoek relaxation and Snoek-Koster relaxation, respectively. The maximum damping capacity can be obtained at about 63Hz. The damping is positive amplitude-dependent, whereas critical amplitude exists where the damping increases dramatically. The temperature-dependent damping results from the superposition effect of point-defect damping, grain boundary damping and interface damping, while dislocation damping is predominant in the frequency dependent damping. The amplitude dependent damping can be interpreted by G-L theory.