Appendix F: Unsupported BDF Content

In general terms, a BDF used for a SOL 400 Nastran implicit nonlinear transient analysis would be suitable to define a nonlinear flexible body. Any temporarily unsupported content can be found in the Known Issues listing for the nonlinear flexible body feature in the release guide. Other considerations are described below:

Linear only elements like TRIA6 or CQUAD8 elements are not supported for nonlinear flexbody. If the BDF contains TRIA6 or CQUAD8 elements, then it is strongly recommended to add "NLMOPTS, SPROPMAP, 2" in the main bulk section of the BDF to convert these linear only elements to advanced nonlinear elements. For more details see the description of SPROPMAP (Secondary Property Map) under the NLMOPTS (Nonlinear Multiple Options) entry in the MSC Nastran Quick Reference Guide. An example of adding NLMOPTS into BDF is shown below.

Adams does not automatically add "NLMOPTS, SPROPMAP, 2" when it encounters TRIA6 and CQUAD8 elements in the model because this option affects all elements in the model (this option is not specific to TRIA6 and CQUAD8 elements), converting them to advanced nonlinear elements and this may not be the intention of the Adams user.

Nonlinear flexible body definitions do not support modeling techniques in the BDF which would result in MSC Nastran SOL400 to perform some analysis iterations in order to arrive at a proper initial condition. Examples include the use of BOLT elements and contact representations where there is initial penetration between the contact surfaces. Since BOLT elements require this analysis iteration to resolve the preload, Adams will issue an error message when BOLTs are present in the BDF. In the case of contacts, an analysis iteration is activated by the BCTABLx,0 card in bulk data section and optional BCONTACT=0 card incase control. If present in the BDF, Adams will comment them out and issue a warning message: