Joe Woosman
Member
Boyd,
I believe these other examples sound good to talk about but are ultimately confusing without a deeper knowledge of harmonics in materials. The roller coaster frame harmonic issue was further complicated by the restrictions to added weight to the structure. Compromises had to be made since they couldn't fill the tubes with concrete or some other optimal material.
Particle dampening has its place but its not in an application that has no weight restrictions. In a wing tip maybe, in a fancy barrel tuner maybe as well. From the studies I have read on particle dampening it seems to shine in an application where the particles are changing directions with the frequency. The particles carry a kinetic energy and impart that onto the part of the structure reversing direction in the wave, damping its motion. That's how I understood it anyway.
Someplace a while back I saw you posted a link to acoustic foam as a means of reducing the sound transmitted through a wall. This is the same sort of thing. The foam will prevent an erratic deflection of the sound waves but the waves will pass right through it without reducing it much at all. On the inside of the room we would have the perception that the sound has been reduced or absorbed but in fact it has not.
You are correct that adding oil and sand to a tube will reduce the "ting" to a thud. Filling it with concrete or lead will make for a duller thud.
I believe these other examples sound good to talk about but are ultimately confusing without a deeper knowledge of harmonics in materials. The roller coaster frame harmonic issue was further complicated by the restrictions to added weight to the structure. Compromises had to be made since they couldn't fill the tubes with concrete or some other optimal material.
Particle dampening has its place but its not in an application that has no weight restrictions. In a wing tip maybe, in a fancy barrel tuner maybe as well. From the studies I have read on particle dampening it seems to shine in an application where the particles are changing directions with the frequency. The particles carry a kinetic energy and impart that onto the part of the structure reversing direction in the wave, damping its motion. That's how I understood it anyway.
Someplace a while back I saw you posted a link to acoustic foam as a means of reducing the sound transmitted through a wall. This is the same sort of thing. The foam will prevent an erratic deflection of the sound waves but the waves will pass right through it without reducing it much at all. On the inside of the room we would have the perception that the sound has been reduced or absorbed but in fact it has not.
You are correct that adding oil and sand to a tube will reduce the "ting" to a thud. Filling it with concrete or lead will make for a duller thud.