How To Perform a Mode-Superposition Harmonic Analysis — Lesson 1

The harmonic response analysis determines the steady-state response of a structure that is subjected to loads that vary sinusoidally over time. This analysis enables us to verify whether the designs will successfully handle resonance, fatigue and other harmful effects of forced vibrations. There are two ways to solve harmonic response analysis: the full harmonic and mode superposition methods. In both methods, all loads must be sinusoidally time-varying and must have the same frequency. Nonlinearities are not permitted and transient effects are not calculated.

The mode superposition method adds up factored mode shapes from a modal analysis to calculate the structure’s response. This method is faster and less computationally intensive than the full harmonic method. The solution can be clustered about the structure’s natural frequencies, providing smoother results and more accurate tracing of the response curve. Any pre-stress effect and modal damping can be included.

Simulation Files

Download the accompanying geometry and archived files here. The student version of Ansys simulation software can be downloaded here.