Stockbridge Dampers

Stockbridge dampers are placed on power lines and light poles to prevent oscillation through resonance. The stockbridge damper is also considered a tuned-mass damper.  You will note that the tuned mass dampers allow the mass to flex up and down, it is not just a weight attached to the powerline.

• What is the purpose of a stockbridge damper?

• What would happen if they were not on?
• Where should these be placed in order to be the most effective? 
• What does it mean by a tuned mass damper?

Students could: 

• Observe this concept in class by oscillating a thick rope by hand or with a mechanical oscillator with string. Then put a small mass at a node, then move to an antinode to see what place is the most effective. (Students should see that dampers are not very effective on the node, and rather effective everywhere else. The mass, and how the mass is mounted also makes a difference. That is the tuned aspect of the tuned mass damper.)
• Extend this thinking into the Tacoma Bridge, and how we use bridge dampers today to prevent it from happening again. 
• Create an argument explaining how this concept also applies to breaking a wine glass with your voice.

• RWDI | Why Dampers Are Important to Reduce Motion on Bridges: This video explains how bridges are affected by motion and how a bridge damping system can improve its performance by counteracting the motion from external forces like wind or pedestrian-induced motion and vibration.
• Slate Magazine | What’s That Thing Hanging From Lampposts and Power Lines?: This is an overview on what stockbridge dampers are and how they work.