PREDICTION OF NEAR FIELD INTENSITY PATTERNS BASED ON MODAL DEFORMATION PATTERNS

Two computational methods for estimating the sound power radiated by mechanical structures are presented. The reported technique fills the gap between structural vibrations and radiated sound and facilitate the accurate assessment of noise reduction measures at the design stage. Both methods, which are based on a helmholtz integral formula, require a knowledge of the geometry and modal characteristics of a structure's vibration surfaces, so that the pressure on the surfaces can be computed. The first method is limited to flat surfaces and replaces the original source by a distribution of point sources which are easy to integrate over the radiating surface. The second method is more general and accurate but requires considerably more computing time since it includes a closed form integration of the associated surface integrals. This paper reviews some principles on acoustic radiation, the algorithms concerned are briefly mentioned, and verification experiments where close correlation was found between predicted and experimentally determined sound power levels, are presented. For the covering abstract of the conference see TRIS 451834. (TRRL)

• Supplemental Notes:
  • Vehicle Noise and Vibration. Papers read at the International Conference held at the Institution of Mechanical Engineers, London 5-7 June 1984.
• Corporate Authors:

  Mechanical Engineering Publications Limited

  P.O. Box 24, Northgate Avenue
  Bury St Edmunds, Suffolk IP32 6BW,   England 
• Authors:
  • Sas, P
  • VAN DE PONSEELE, P
  • Snoeys, R
• Conference:
  • Vehicle Noise and Vibration. Papers read at the International Conference held at the Institution of Mechanical Engineers, London 5-7 June 1984.
• Publication Date: 1984

Media Info

• Features: Figures; References; Tables;
• Pagination: p. 189-195

Subject/Index Terms

• TRT Terms: Acoustics; Algorithms; Conferences; Design; Estimating; Forecasting; Geometry; Mathematical models; Methodology; Motors; Noise control; Pressure; Shape; Sound; Sound level; Surfaces; Vehicle power plants; Vibration
• Uncontrolled Terms: Decreases; Geometry (Shape); Noise reduction
• Old TRIS Terms: Automobile engines
• ITRD Terms: 8525: Conference; 9009: Decrease; 9011: Design (overall design); 132: Forecast; 6473: Mathematical model; 9102: Method; 1334: Motor; 5412: Pressure; 9073: Shape; 6748: Sound; 6747: Sound level; 6438: Surface; 5558: Vibration
• Subject Areas: Design; Highways; Vehicles and Equipment;

Filing Info

• Accession Number: 00451854
• Record Type: Publication
• Source Agency: Transport Research Laboratory
• Files: ITRD, TRIS
• Created Date: May 31 1986 12:00AM