Sound Transmission into Shells Doubly Excited by Incident Waves and by Arbitrary Surface Forcing Functions.
Abstract
We develop the fundamental exact analytical and computational model required to study the transmission of incident plane sound waves into submerged elastic cylindrical shells subjected to arbitrary loads on their outer surface. We use the superposition principle in this linear problem to separate the contributions to the internally transmitted field caused by the incident wave from that of the surface load. This basic model uses the exact (2-D) formulation of elastodynamics to describe the shell motions, and that of general linear acoustics to describe the wave motion in the inner and outer fluids. We display the isobaric contours of the internally transmitted pressure fields, exhibiting their caustics and their progressive development as the frequency is increased within the band 0<k3a<10. The contour plots are generated for all the possible combinations of loading and insonification conditions with a view toward computing an advantage ration which measures the gains that would result from sensing the internally transmitted field, rather than the field external to the shell. This advantage ratio is shown always to be greater than unity and; in many cases, much greater than unity. We performed a detailed computational study to quantitatively determine the effect of shell thickness, stiffness, and general material composition, on the sound fields transmitted into the loaded shells. This analysis makes the work valid for various metals and for shell relative-thickness between 1% and 20%, which is a range covering most practical cases.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 15, 1985
- Accession Number
- ADA159936
Entities
People
- G. C. Gaunaurd
- J. Barlow
Organizations
- Naval Ordnance Laboratory