Engaging Energy Based Structural-Acoustic Simulations in Multi-Discipline Design 2009-01-2198

In order to be effective and maximize the weight and cost savings when designing for noise and vibration attributes, the structural-acoustics design effort must be concurrent with the efforts of other engineering disciplines (i.e. durability, crashworthiness, etc.). In this manner, it will be possible to account for the effects of structural changes across disciplines and improve the NVH performance while the structure is being configured rather than attempting to improve NVH characteristics after the structural design has been completed. Two key enablers must be available in order to perform such multi-discipline design: (i) the structural-acoustics simulations must use a finite element model similar to the simulations of all other disciplines in order to have commonality between design variables and simulation models; (ii) a flexible Multi-discipline Design Optimization (MDO) capability must be available for driving simultaneously multiple separate optimization analyses, facilitating the exchange of data among the disciplines, and accounting for impact of changes introduced by a particular discipline to all others. In this paper, the Energy Finite Element Analysis (EFEA) is employed for performing energy based vibro-acoustic analysis within a finite element framework. A software implementation of the Target Cascading (TC) method is utilized for driving the MDO analysis. It allows for solving simultaneously multiple individual optimizations for each discipline with separate objective functions and constraints, while at the same time pursuing an overall system level weight or cost objective. A case study is presented for the multi-discipline design analysis of a scale aircraft structure (NASA aluminum test-bed cylinder) under crash, pressurization, structure-borne noise, and air-borne noise considerations. In order to demonstrate the importance of the multi-disciplinary design, the results from the system level optimum configuration are compared with results obtained from individual single discipline design efforts.