This report documents the results of Task 14, "Structural Acoustic Prediction and Interior Noise Control Technology". The task was to evaluate the performance of tuned foam elements (termed Smart Foam) both analytically and experimentally. Results taken from a three-dimensional finite element model of an active, tuned foam element are presented. Measurements of sound absorption and sound transmission loss were taken using the model. These results agree well with published data. Experimental performance data were taken in Boeing's Interior Noise Test Facility where 12 smart foam elements were applied to a 757 sidewall. Several configurations were tested. Noise reductions of 5-10 dB were achieved over the 200-800 Hz bandwidth of the controller. Accelerometers mounted on the panel provided a good reference for the controller. Configurations with far-field error microphones outperformed near-field cases.Mathur, G. P. and Chin, C. L. and Simpson, M. A. and Lee, J. T. and Palumbo, Daniel L. (Technical Monitor)Langley Research CenterAIRCRAFT NOISE; ACOUSTIC ATTENUATION; MATHEMATICAL MODELS; TECHNOLOGY UTILIZATION; CONTROLLERS; AIRCRAFT STRUCTURES; NOISE REDUCTION; ACCELEROMETERS; FLIGHT TESTS; FUSELAGES; SOUND TRANSMISSION; FINITE ELEMENT METHOD

Multidisciplinary Design and Optimization of Aerospace Composite Materials is a collection of ten SAE technical papers focusing on the design analysis of aerospace composite structures from the perspective of various disciplines. The book concentrates on the following aspects: • Analytical methods for weight design of aircraft structures, including a parametric geometry model capable of generating dedicated models for both aerodynamic and structural solvers. • Methodologies for evaluating the structural performance of carbon/epoxy composite panels. • An aerodynamic design of flexible wings made of composite structures. • Thermal design and analysis of composite enclosures. • Methodologies for analyzing the acoustic performance of composite structures, including the design optimization method to evaluate the acoustic performance in terms of transmission loss (TL) of various composite panels. • The lightening effect on composites, presenting a theoretical method to compute the electrical current propagating through composite structures due to lightning strikes. • The issue of fire resistance as most polymer resins are flammable once the respective ignition temperatures are reached. • A probabilistic-based reliability analysis of the composite structures. The method is demonstrated on a graphite/epoxy composite space habitat subjected to the debris attacks. • A sustainability analysis of aircraft composite materials, including improved durability, less maintenance, and lower energy consumption.

The book describes analytical methods (based primarily on classical modal synthesis), the Finite Element Method (FEM), Boundary Element Method (BEM), Statistical Energy Analysis (SEA), Energy Finite Element Analysis (EFEA), Hybrid Methods (FEM-SEA and Transfer Path Analysis), and Wave-Based Methods. The book also includes procedures for designing noise and vibration control treatments, optimizing structures for reduced vibration and noise, and estimating the uncertainties in analysis results. Written by several well-known authors, each chapter includes theoretical formulations, along with practical applications to actual structural-acoustic systems. Readers will learn how to use vibroacoustic analysis methods in product design and development; how to perform transient, frequency (deterministic and random), and statistical vibroacoustic analyses; and how to choose appropriate structural and acoustic computational methods for their applications. The book can be used as a general reference for practicing engineers, or as a text for a technical short course or graduate course.