SUMMARY

A third-generation of in-line, liner-style hydraulic suppressors was developed that takes advantage of advancements of syntactic foam technology. The chemistry of the developed liner was varied so that the acoustic properties of the foam could be retained when repetitively exposed to the extremes of the hydraulic environment. The developed liner uses microspheres that can be charged to an elevated initial microsphere pressurization which results in an increased acoustic performance at elevated system pressures. The developed liner also addresses the limitations of the first and second-generation liner-style suppressors in terms of initial volume fraction of microspheres, allowing for enhanced acoustic performance over broad pressure ranges.

Acoustic diffusers, necessary for bladder-style in-line hydraulic suppressors, were considered for use with liner-style hydraulic suppressors. It was found that acoustic suppressors are not appropriate for use in liner-style suppressors due to the possible dimensional changes of the liner under hydrostatic loading.

Testing indicates that increasing the initial microsphere pressurization and the initial volume fraction of microspheres significantly increases the acoustic performance of the suppressors. Additional testing indicates that the host matrix composition can be refined so that the acoustic performance is stable over multiple exposures to elevated temperature and pressure. Using the results of the testing, a suggestion for an improved formulation of syntactic foam is made.