A study on damping characteristics of mechanical snubber

Design attenuation constant is one of the important elements for the aseismatic design of the piping system for nuclear power stations together with input earthquake motion and allowable stress. In Japan, the conservative value based on the recommended value of Hausner has been used. The elucidation of the damping characteristics of mechanical snubbers is very important for clarifying the damping characteristics and evaluating the aseismatic ability of piping system. In this study, the element test and the piping model test were carried out, and the equation for evaluating the damping effect of mechanical snubbers and the mechanical model representing their vibrational characteristics were proposed. The propriety of the equation for evaluation and the mechanical model was confirmed by the piping model test. The construction of two mechanical snubbers tested, the method and results of the element test, the analytical evaluation of the attenuation constant of piping system, the mechanical model of a mechanical snubber and the piping model test are reported. When exciting frequency was lower than the natural frequency of mechanical snubbers, the dynamic rigidity increased with the exciting frequency, and the reaction force was inertial mass type. When it was higher, the dynamic rigidity was constant, and the reaction force was spring type. (Kako, I.)