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Non-linear Elastic

To specify non-linear elastic behaviour, rather than inputting a single value of Young’s modulus you input instead a direct stress-strain (σ-ε) relationship. This defines both non-linear bending and non-linear axial response. You are still required to input a (single) value for shear modulus – the option to specify non-linear torsional response is not available with this format, but this option in any event has limited usage. Note also that you cannot combine non-linear bending response with linear axial behaviour, and vice versa.

What actually happens in this case is that Flexcom transforms the direct stress-strain relationship into moment/curvature and axial force/axial strain curves for each element of the set in question, based on I and A values for that set. Thereafter the operation is the same as for the Flexible Riser format. Note however that non-linear bending response with the Rigid Riser format is (necessarily) Symmetric by the above definition.

Refer to Non-linear Material Force Term for further information on how the Flexcom solver accounts for non-linear materials in the equilibrium equations.