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Hoses and umbilicals: Axial and bending stiffness |
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Hoses and umbilicals: Axial and bending stiffness |
The line type wizard derives stiffness data and sets compression is limited for hoses and umbilicals as follows.
For each type of hose the axial and bending stiffnesses are calculated as a function of inner diameter \begin{aligned} \text{axial stiffness} &= \begin{cases} 2.80{\times}10^6\, I\!D\ \text{ kN} &\text{for high pressure } (40\%-160\%) \\ 3.40{\times}10^4\, I\!D\ \text{ kN} &\text{for low pressure } \\ 6.56{\times}10^3\, I\!D\ \text{ kN} &\text{for fold-flat } \end{cases} \\ \\ \text{bending stiffness} &= \begin{cases} 3{\times}10^4\, I\!D^4\ \text{ kN m$^2$} &\text{for high pressure } (45\%-300\%) \\ 6{\times}10^2\, I\!D^3\ \text{ kN m$^2$} &\text{for low pressure } \\ 1{\times}10^3\, I\!D^3\ \text{ kN m$^2$} &\text{for fold-flat } \end{cases} \end{aligned}
For umbilicals, the axial stiffness has been estimated as a function of outer diameter \begin{aligned} \text{axial stiffness} &= 1.44{\times}10^6 O\!D \text{ kN} (15\%-415\%)\\ \text{bending stiffness} &= 3{\times}10^3 O\!D^3 \text{ kN} (55\%-240\%) \end{aligned}
As the bending stiffness is significant for both hoses and umbilicals, compression is not limited.