Abstract
This study has examined the forming process and its characteristics of bell structures with the use of batch type foaming that the blowing agent of a supercritical fluid was used. In this study, various forming methods have been tried for bell structures together with a series of impact tests and acoustic tests of the structures, followed by evaluation of shock absorption and sound insulation for inclusion of particles. The trial succeeded in forming the bell structures including various kinds of balls by means of batch type foaming. As results, the following have been confirmed. (1) Bell structures exhibit shock energy absorption effect. (2) Bell structures exhibit sound insulation effect. (3) A simplified model to represent the motion of particles in the air gap of a bell structure and associated frictional force was shown, and a relationship between the air gap and particles that affects a damping characteristic was studied. The results suggest that the distance between the air gap inner wall and the particles makes a great contribution as an element for enhancing the damping characteristic.
