SubDyn issue when rigid links are connected to interface and cable

[ebranlard]

Bug description Loads and displacements are wrong when rigid links are connected between the interface node and nodes that have cables.

To Reproduce Use this test case. https://github.com/OpenFAST/r-test/main/f/SD-Loads/modules/subdyn/SD_Rigid2Interf_Cables

Expected behavior IntfZss is 4.6e6N where a value of 2.23e7N would be expected.

OpenFAST Version Dev version as of October 2021. Bug present ever since the rigid link feature was introduced (around OF 2.6).

[rafmudaf]

The test case references above that exposes the bug is now in the main branch at https://github.com/OpenFAST/r-test/tree/main/modules/subdyn/SD_Rigid2Interf_Cables

[RBergua]

I do believe the problem is related to defining one beam at the interface joint and, at least, one rigid link to that same interface joint. For example: If I define a rigid link that is used to connect a lumped mass to the interface joint, such a mass is somehow not taken into account. Despite SubDyn reporting the expected mass and inertia in the summary file.