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![orcaflex 2rd limiting stress orcaflex 2rd limiting stress](https://www.researchgate.net/profile/Yangye-He/publication/337515496/figure/fig4/AS:829970846871552@1574891878039/OrcaFlex-effective-tension-time-series-at-s92m_Q320.jpg)
The von Mises stress varies across the cross section, so its value is reported at a specified cross section position, $(R,\theta)$. For example, the bending stress is calculated as $|\vec3$ stress matrix. We use the same formulae for stress calculation as for linear stiffness. If the pipe has nonlinear stiffness then OrcaFlex cannot, in general, accurately calculate pipe stresses. These assumptions mean that the stress calculations are only valid for pipes such as steel or titanium risers, not for composite flexible risers, ropes chains, etc. However the effect of dynamic variations in pressure, for example from the passage of the wave, are not included.
![orcaflex 2rd limiting stress orcaflex 2rd limiting stress](https://www.orcina.com/webhelp/OrcaFlex/Content/image/StressJointFigure2.png)
The hoop stress due to static internal and external pressure at the current $Z$-level is included, and is calculated using the standard Lamé equation for thick walled cylinders.Although this is not strictly the case, the shear stress is normally negligible so this simplifying assumption is reasonable. For the purpose of calculating the components of the stress matrix, the shear stress is assumed to be uniformly distributed across the cross section.Internal pressure in the line generates wall tension in the line as it would do in a sealed cylinder.Scaling is done either by the stress loading factors, or will be done automatically if homogeneous pipe additional bending stiffness is in use. The loads (tension, bend moment, shear and torque) which are used in stress calculations are scaled before being used.The stresses included are those due to tension, bending, shear and hoop stress.At each point along the line all the loads are taken by a single simple cylinder of the specified stress OD and stress ID and made of a homogeneous material.The stress calculations make the following assumptions (for terminology see the pipe stress calculation topic): Stress and strain results are available at mid-segment points and at line ends.