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DynaRod - Dynamic Rod Deflection Simulator   


Dynamic Deflection is an opposite word to Static Deflection, and implies something which is moving with flexure.  

Static Deformation, or Static Deflection, which was described by Everett Garrison first, uses such mathematics that calculates moment and acquires stress value from the moment, like structure engineering.  The mathematics does not assume that a rod to be deflected while calculating the moment figure.  As the stress value is the result of division of the moment by section modulus, it does not imply anything related with rod deflection, easiness of bending due to the nature of its material.  So, it has a little difficulty to understand which kind of rod could be resulted when we design the rod by the method.

Garrison's method, however, which was established in the days of slide rule, still has a value in the rod design among contemporary rod makers.  I also studied this method and received its benefits when I started rod making.  It is also true that  several questions were  being felt while using it.

At first, the method was difficult to imagine the resulted rod by looking at the stress curve.  Another point is that the math is always the same even if I use different kind of bamboo from Tonkin, for instance, Japanese specie, Madake or Hachiku.  Actually, such bamboo's are softer than Tonkin.  It means that the math does not take the difference of rod blank material  into account.  The only material related factor is the weight of bamboo which will generate moment.

Aside those questions, several trials were made to draw a rod deflection from the calculated result via Garrison's math but all the efforts were in vain.  The rod deflected in an odd fashion.

Then, the author got away the great Garrison's method once, and started to walk through the rules of physics from the beginning.  What is the reason why a rod bends?   Why a rod is not broken even if  it is bent?  Why a rod recoils?  etc., etc..  Everything was questioned.  The physics text book of high school gave me an appropriate level of difficulties and understandings for such as velocity, acceleration, equal velocity movement, equally accelerated movement, inertia, force of inertia, air resistance, elasticity, modulus of elasticity, mass, gravity, weight, flexural rigidity, moment, stress, strain, flexure, etc., etc..   Oh, what a stress it was to study all of these by my tired brain!

Here today, at last, I completed usable level of simulator.  It will try to answer to the questions of how to give a certain load to a rod, which kind of force will act to a rod, how a rod will bend under a given load, how to reflect the difference of blank materials, how a taper differs when it is hollow made or in different cross sections, how moment would vary in a rod movement, how the change is reflected to the bend, how to treat convergence problem in calculation, etc., etc..  Many of those questions were resolved in this simulator.

DynaRod implemented not only such described physics rules as above, but several considerations of rod design and rod making as the author was eventually the person who makes bamboo rods.

In addition to designing Fly rod, DynaRod can also design Lure rod and Boat rod.   All the necessary information of Guide set are pre-defined in the tables by the author.

Hoping it becomes an easy to use contemporary rod design tool and rod casting simulator.

Max Satoh      January 15, 2006