Non-Obstructive Particle Damping: New Experiences and Capabilities

Non-Obstructive Particle Damping (NOPD) technology is a passive vibration damping approach whereby metallic or non-metallic particles in spherical or powder form, of heavy or light consistency, and even liquid particles are placed inside cavities or attached to structures by an appropriate means at strategic locations, to absorb vibration energy. Numerous laboratory experiments and applications on hardware have been carried out at PWR-CP. Test results are summarized in the following paragraphs to provide an overview of the technique and the effectiveness of particles as a means for damping vibrations as well as for acoustic attenuation. Specific applications and capabilities are presented regarding some of the major test/development programs undertaken during the past years at PWR-CP. Nomenclature b = inverse of the amplitude of the relaxation time, effective damping parameter 2 0 ω = natural frequency ζ = damping ratio x = displacement F = force t = time A = amplitude of motion m = mass ( = Average displaced power per cycle cyc W )