RANSTEP - Reduced order Analysis using a Nonlinear STiffness Evaluation Procedure(LAR-17262-1)

A new implementation of reduced order finite-element-based analysis for solving geometrically nonlinear random vibration problems of complex structures has been developed. The implementation is given the acronym RANSTEP for Reduced order Analysis using a Nonlinear STiffness Evaluation Procedure. The nonlinear stiffness evaluation procedure allows computation of otherwise inaccessible modal nonlinear stiffness terms from commercial finite element programs. Some operations are performed outside the commercial codes and utilize in-house developed FORTRAN codes. Additionally Direct Matrix Abstraction Program (DMAP) alters and PYTHON scripts are used to facilitate implementations written about MSC.NASTRAN and ABAQUS, respectively. Two solutions procedures of different fidelity and computational cost are offered in each implementation. They are equivalent linearization and time numerical simulation. Aerospace uses include aircraft and spacecraft structural analysis.