Design Minimization of Noise in Stiffened Cylinders Due to Tonal External Excitation

Cunefare, Kenneth A.; Crane, Scott P.; Engelstad, Stephen P.; Powell, E. A.

doi:10.2514/2.2471

Cited by 18 publications

(21 citation statements)

References 7 publications

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“…In Fig. 10b, a sinusoidal variationin stiffness properties around the circumference is evident for both cases (this result has also been found in earlier work by the authors in which the same cylinder was optimized using shell element thicknesses as the design variables 11 ). For case I, the stringers were nominally 90% of original size and for case II were 87% of original size.…”

Section: Single Frequency Beam Shape Optimizationsupporting

confidence: 63%

“…We have also shown in other work that even when we begin with an off-resonance starting point, the algorithm still tends to locate similar optimal designs as found when we begin on-resonance. 11 In later work we plan to discuss multifrequency optimization in which we reduce all of the peaks in a prescribed frequency band and at each iteration recompute the structural and acoustic natural modes and optimize, always following the peaks in the bandwidth. This is called peak tracking.…”

Section: Single Frequency Beam Shape Optimizationmentioning

confidence: 99%

“…The present work is part of an ongoing research program to develop and validate a robust computationaltool to minimize noise transmission into stiffened cylinders through the modi cation of the structural design. 4,10,11 Existing analysis tools have been utilized to solve the coupled structural acoustic problem, and a UNIX shell script maintains control and coordinates the iterative design process, integrating the programs. The present study is an application of this tool, in which the stiffener cross section dimensions and overall sizing is modi ed to achieve the improved interior noise environment.…”

Section: Introductionmentioning

confidence: 99%

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Stiffener Shape Design to Minimize Interior Noise

Engelstad

Cunefare

Powell

et al. 2000

Journal of Aircraft

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Results of a research program to develop computational methods to minimize noise transmission into aircraft fuselage interiors are discussed. A design tool to perform a constrained optimization of the acoustic environment within a vibrating structure is developed utilizing nite element methods and boundary element methods (FEM/BEM), and its application to aircraft cabin noise problems is studied. The results of a study to optimize the cross section shapes of frames and stringers of an idealized aircraftlike stiffened cylinder are reviewed. The structure is optimized for minimum noise at speci ed points in the interior, as a result of a single frequency (tonal) exterior acoustic disturbance. For the cylinder and excitation frequency studied, it has been found that spatially varying the stiffener sizes over the cylinder is more important than optimizing the shape of the cross sections. Because FEM/BEM methods are only reliable for lower frequencies, the problems studied are applicable to low-frequency tonal noise such as seen in turboprop aircraft. Nomenclature vectors of lower and upper bounds F(b)= objective function f 0 = initial value of objective function p i (b) = complex acoustic pressure at node i S = scale factor design variable v = normal velocity of shell structure, or acoustic velocity at shell wall W = structural weight W max = constrained maximum weight x i , y i = coordinate design variables at node i

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Section: Single Frequency Beam Shape Optimizationsupporting

confidence: 63%

Section: Single Frequency Beam Shape Optimizationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Stiffener Shape Design to Minimize Interior Noise

Engelstad

Cunefare

Powell

et al. 2000

Journal of Aircraft

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“…With respect to these results, they emphasized the particular value of structural-acoustic optimization in passive noise control. In references [13,14], they presented the results of optimal geometry and cross-sectional shapes of frames and stringers. A reduction of 8)6 dB was gained mainly by optimizing the geometry of the sti!ening structures over the cylinder.…”

Section: Introductionmentioning

confidence: 99%

Experimental Verification of Structural-Acoustic Modelling and Design Optimization

Marburg

Beer

Gier

et al. 2002

Journal of Sound and Vibration

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“…An interesting study of optimally distributed damping material on a circular plate has been provided by Wodtke and Lamancusa. 56 More realistic applications were discussed by Cunefare and Engelstad et al [10][11][12] Their example, a cylinder clamped at both ends and acoustically excited by a monopole source from outside appears roughly similar to an aircraft fuselage. However, investigation of shell thickness optimization as well as optimal positioning of stringers and frames for stiffening look reasonable to conclude for more complex aircraft constructions.…”

Section: Introductionmentioning

confidence: 96%

Investigation and Optimization of a Spare Wheel Well to Reduce Vehicle Interior Noise

Marburg

Hardtke

2003

J. Comp. Acous.

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Optimization of structures with the intention to reduce noise emission has become an efficient tool during the past decade. Various approaches and applications have been published and will be briefly reviewed in this paper. Then, the structural component model of a spare wheel well and the fluid model of a sedan cabin are described. The noise transfer function is defined as the sound pressure level in vicinity of the driver's ear due to a harmonic force excitation at engine supports. The frequency range of 0-100 Hz is considered. In a first investigation, it is tested whether stiffening of the entire structural component really decreases the noise transfer function. It can be seen that this stiffening mainly affects noise emission in the upper frequency range. In a contribution analysis, i.e. analysis of the surface contribution to the noise at the driver's ear, the original model and the stiffened model are compared. This contribution analysis includes frequency ranges by summation of contribution and/or contribution levels. Modification of the structure by design variables consists of modification of the shell geometry, i.e. curvature. Two regions are selected at the bottom of the wheel well. Optimization of 30 design variables leads to a gain of 1.15 dB in the objective function being the root mean square value of the sound pressure level at the driver's ear. Finally, we discuss the results. In most papers on structural acoustic optimization, higher decreases have been reported. An explanation is provided, why this was not possible for the structure that has been investigated here. The new shape, however, seems to be a reasonable choice.

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Design Minimization of Noise in Stiffened Cylinders Due to Tonal External Excitation

Cited by 18 publications

References 7 publications

Stiffener Shape Design to Minimize Interior Noise

Stiffener Shape Design to Minimize Interior Noise

Experimental Verification of Structural-Acoustic Modelling and Design Optimization

Investigation and Optimization of a Spare Wheel Well to Reduce Vehicle Interior Noise

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