Hi,
I am currently working on a rail project and i’m having a problem with the formula of cubic parabola. I would appreciate if you could give me any tips/advice.
Here is my problem:
For the spirals i have to use the cubic parabola type.
C3d 2014 supports the formula for cubic parabola, but the simplified one: y=(x^3) / (6*R*L)
Unfortunately this formula is not acceptable for my client .
The formula that needs to be applied is: y=(x^3) / [6*R*l* (cos^(3) τ)]
Have anyone faced a similar situation before?
I am wondering if there is a way to modify the current equation of cubic parabola, or if a third-party plug-in is developed for that purpose.
Thank you in advance.
Forgive me as I've never used a "cubic parabola" before (or spirals in C3D) but the only real difference I see between the two formulas is instead of L, you've got (cos(3)*t). So is that just more accurate than L? Meaning is L that number but rounded? If so, can't you somehow adjust the rounding that the formula uses?
Don Ireland
Engineering Design Technician
Don:
I think you may have overlooked something. I believe that is a lowercase "L" he typed in that one formula. All I know about it, but it must be somewhat significant.
Bill
I would like to thank you very much for your prompt responses. Time is very critical for us, so in order to make myself more clear, i am attaching images explaining all about the equation (in English).
As mentioned before, Civil 3d uses the simplified formula to solve cubic parabola, but for my client the only acceptable equation is the complicated one (in the green box).
And i am still wondering:
Have anyone faced a similar situation before?
Is there a way to modify the current equation of cubic parabola in civil 3d?
Or is it possible a third-party plug-in to have been developed for that purpose?
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