A Mechanical Power Flow Capability for the Finite Element Code NASTRAN
Abstract
Structure-borne sound is the vibrational energy which travels through dynamically loaded mechanical systems. This vibrational energy is radiated eventually into an acoustic medium as noise. An example cited by Wohlever and Bernhard1 is an airplane wing loaded by engine vibrations. The vibrational energy travels along the wing ot he fuselage and is radiated as sound into the cabin. The identification of power flow paths in dynamically loaded structures is an important, but currently unavailable, capability for the finite element analyst. For this reason, methods for calculating power flows and mechanical intensities, and in finite element models are developed here. Formulations for calculating input and output powers, power flows, mechanical intensities, and power dissipations for beam, plate, and solid element types are derived. NASTRAN is used to calculate the required velocity, force, and stress results of an analysis, which a post-processor then uses to calculate power flow quantities. The SDRC I-deas Supertab module is used to view the final results. Test models include a simple truss and a beam-stiffened cantilever plate. Both test cases showed reasonable power flow fields over low to medium frequencies. Future work will include testing with more complex models, developing an interactive graphics program to view easily and efficiently the analysis results, applying shape optimization methods to the problem with power flow variables as design constraints, and adding the power flow capability to NASTRAN.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 01, 1989
- Accession Number
- ADA212202
Entities
People
- Stephen A. Hambric