Newly developed specification and test methods for syntactic foam buoyancy material for deep ocean manned submersible vehicles

Syntactic foam buoyancy material is a critical item in the performance of deep ocean manned vehicles. The only known specification for syntactic buoyancy material for high hydrostatic pressures is MIL-S-24154A(SHIPS). This MIL spec dates back to 1967 with the last amendment dated 1991 and it does not incorporate the latest advances in the testing of syntactic materials nor the knowledge and experience base which has been obtained as a result of its use over the last 20 years. This paper presents the syntactic buoyancy material specification developed by the Woods Hole Oceanographic Institution for the manned submersible vehicle Alvin. The specification incorporates the best testing practices of syntactic materials for use in submersible vehicles to insure the required performance of deep water buoyancy material. In addition, this paper presents a method for utilizing an acoustic emission testing technique to determine the depth at which structural breakdown of the syntactic material occurs.