All composite mdata files stored in your Helius PFA materials directory are saved with the N/m/K unit system. However, when preparing your FEA model in Autodesk Inventor Nastran, the N/m/K units may not be the most appropriate. To run Helius PFA with Autodesk Inventor Nastran, you must define the units via the PARAM, UNITS entry. For example:
PARAM, UNITS, IN-LBF-BTU-SECThe PARAM, UNITS entry will tell Helius PFA the unit system to use to compute constitutive relations and stresses. If the unit system chosen is different that the N/m/K system used to store material data, Helius PFA will make the appropriate conversions. Refer to the UNITS parameter in the Autodesk Inventor Nastran Reference Guide for more information.