Experimental Investigation on Dynamic Characteristics of NOPD Thin-Wall Frame Structure

The free vibration experiments for the NOPD frame structure were performed to investigate the dynamic characteristics of the frame. The influences of factors such as particle filling ratio, particle filling scheme and vibration direction of the frame on the damping effect are discussed by means of test data. Test results indicate that the particle filling ratio is a principal influencing factor for the damping effect of the frame. Under the same particle filling scheme and filling ratio, the damping increments for out plane vibration of the frame with smaller structural rigidity are normally larger than those for in plane vibration with larger structural rigidity. Within the three schemes of particle filling, the most prominent damping improvement exists in the particle-in-beam scheme under the same filling ratio and the corresponding maximum damping increment reaches 218% for out plane vibration. To obtain the most significant particle damping effect, the most effective scheme of particle filling is to put particles into the cavities of components with large vibration displacement.