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FP_101198334-Participant
4-Participant
January 5, 2024
Question

Issue with odesolve boundary conditions

  • January 5, 2024
  • 1 reply
  • 1270 views

Hello everyone

 

I have been trying to study the dynamic response of a vertical cylindric pile partly submerged in the sea and resting on the seabed, using Mathcad Prime 8.0. I have implemented the 1D dynamic beam equation as described at https://en.wikipedia.org/wiki/Euler%E2%80%93Bernoulli_beam_theory

 

The pile is free at the top, held laterally in place at height H and simply supported at the base (with a lateral spring). I have defined the following boundary conditions. w and v are deflection and curvature. The units look correct to me. Besides, making the sheet unitless does not solve the problem.

FP_10119833_0-1704456420551.png

Could anyone point me towards the solution or shed more light on what is meant by "inconsistent conditions" ? I have attached the spreadsheet and datafile for some trials.

One issue I see with the file is that I(x) and q(x) have discontinuities so Mathcad may have difficulties evaluating I''(x) over the complete interval.

 

Best regards

 

François

1 reply

L
LucMeekes23-Emerald IV
23-Emerald IV
January 5, 2024

It will not solve the error, but your second de contains w(x) before and after the =.

I guess one or the other should be a derivative of w(x)....

 

What may help to prevent the error is if you (can) split the problem into partial solutions for each of the turning points that you've hidden in the functions q(x) and mu(x).

 

Success!
Luc

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