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Originally Posted by windyridge50
I think you have to think of mass, stiffness and damping as three independent variables. Obviously a heavy tripod is preferable, as for any given force input the resultant acceleration will be less, also a stiffer tripod is good for the same reason that for a fixed force input the displacement will be less. So I agree with you on this.
However once the tripod is in motion the vibration is controlled by damping. the normal way of expressing damping is by the use of a term called tan d (d is really delta but I can't get the symbol here) where tan d is the ratio of the imaginary to real component of the complex Young's modulus (E) where E*= E'+jE" and tan d=E"/E'. A structure with a tan d of 2 is called "dead beat" and for any given energy input will come to rest in less than one cycle of vibration, typical welded steel structures will have a tan d around 0.001.
Damping may be of the coulomb friction type (two bits of metal rubbing together, say in a bolted joint,) or may be tuned to a specific application by the use of a viscoelastic polymer treatment.
The general solution for any vibrating system, treated as a "lumped parameter" system is covered by a second order differential equation, but for higher frequencies, where "wave effects" can throw up a number of nasties in a "distributed system" a one-dimensional solution of the three dimensional wave equation provides a much more precise answer.
Hope this helps :-)
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Fascinating stuff. Would it make sense to fill the legs of a triopd with a foam substance? Obviously this could only be done for the lower sections, but for a two section tripod it would be feasible.
Also bracing seems not to be used these days. But would some form of bracing between the legs help? I'm thinking about something light such as elastic bungee straps linked to each leg via a hook and linked together via a central ring. Obviously this would be slightly fiddly to set up, but would not add much weight.
Leif