Conversion from Nastran to SLDPRT is not supported yet :(

MSC Nastran is a multidisciplinary structural analysis application used by engineers to perform static, dynamic, and thermal analysis across the linear and nonlinear domains, complemented with automated structural optimization and award winning embedded fatigue analysis technologies, all enabled by high performance computing.

Engineers use MSC Nastran to ensure structural systems have the necessary strength, stiffness, and life to preclude failure (excess stresses, resonance, buckling, or detrimental deformations) that may compromise structural function and safety. MSC Nastran is also used to improve the economy and passenger comfort of structural designs

A SLDPRT file contains a 3D part created in the SOLIDWORKS design software.

Multiple SLDPRT parts can be independently modified and combined into a single SLDASM assembly file. If one SLDPRT part belongs to several assemblies, then after modifying it, the changes will appear in all assemblies.

SLDPRT are proprietary files with closed specifications. Nevertheless, some APIs (like CAD Exchanger SDK) provide the facility to read and convert them to other formats.

In addition to SOLIDWORKS software, SLDPRT files are supported by Autodesk Fusion 360.