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- Mar 23, 2000
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Ah! Finally found the other thread I was looking for-
Simulation of blade properties
In many cases in these threads guys are making the assumption that the pivot point associated with the crossguard (or just behind- Cliff called this the "dynamic balance point") is at the same location as the harmonic node or COP. I gather this makes things much easier for calculations and such, but this is by no means absolute. The COP must always (obviously) be on the blade. The forward pivot point corresponding to the cross may well be off the end of the blade. I have such a sword.
Bors
All objects when excited sympathetically or by force will vibrate at a natural frequency or set of natural frequencies the lowest of which is the fundamental frequency. These frequencies are associated with a standing wave pattern. Standing waves are described as reflected waves from one end of the medium that interferes with the incident wave and establishes specific points (nodes) along the medium that have the appearance of standing still. These patterns are only created at specific frequencies and are known as “Harmonic Frequencies” or simply harmonics. Frequencies other than these result in irregular non-repeating wave patterns.
Holding a sword vertical and striking the pommel or handle, we establish a harmonic pattern in the blade. Within the pattern we see two interference points or “Nodes” one is located in the upper third portion of the blade the other is located near the guard. The one in the upper third is often call the “sweet spot” or more commonly the center of percussion (COP).
Can you post a pic of the blade?
You wouldn't by chance happen to have a video of you sword vibrating?
The reason I ask is I don't believe it can (or will favor such a pattern).
At the lowest frequency the quite zones will be precisely at each end. The sword/flat bar will have a continuos arc in it. This frequency is generally not favored but can be induced. This is the lowest frequency any bar, sword ect. will vibrate at.
The next frequency up will move the quite zones inward creating the COP and the lower zone at the handle. This typically is called the "fundamental frequency" or the lowest frequency the sword will "favor".