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Today’s sailors are asked to perform ever-increasing tasks and thus need to be at peak performance. Restful sleep is essential to achieving this peak performance, yet the close working quarters inside submarines can be detrimental to sleep cycles. Therefore, the use of materials to bolster the natural sleep cycle for more restorative rest is desired. Additionally, sound damping materials can be used to reduce mechanical or other noises onboard Navy submarine and surface ship platforms.

Texas Research Institute Austin, Inc. (TRI Austin), developed a noise control material (Figure 1) that possesses the required physical and environmental properties for internal shipboard applications while meeting the stringent fire, smoke, and toxicity (FST) requirements of MIL-STD-2031 entitled “Fire and Toxicity Test Methods and Qualification Procedure for Composite Materials Used In Hull, Machinery, and Structural Applications Inside Naval Submarines”, see Table 1 below. 

Table 1. MIL-STD-2031 Test Results for TRI Austin’s Sound Damping Material
Figure 1. Quiet Bunks Sound Damping Material that meets MIL-STD-2031
Table 2. Mechanical Properties

The material system was tested for Sound Transmission Loss at ETS-Lindgren Acoustic Research Laboratory in Cedar Park, TX (a NVLAP-accredited laboratory, Scope of Accreditation under Lab Code 100286-0).  At one inch thickness, the material achieved an excellent Sound Transmission Class (STC) of 35 (per ASTM E413) and Outdoor/Indoor Transmission Class (OITC) 31 (per ASTM E1332) in Sound Transmission Loss testing (per ASTM E90). 

ETS-Lindgren Acoustic Research Laboratory Sound Transmission Loss (ASTM E90) Test Results – Results Summary Table

Our new sound damping material is cost effective and easy to use.  This new material can be clad/co-cured in metal or composite skins.  Low temperature cure (200° F) enables the material to be fabricated in place on a submarines and surface ships. 

The material’s low density lends itself to weight-sensitive applications.  The material properties and density are shown in Table 2.  Applications include aerospace, maritime, automotive, and architectural products. 

Figure 3. Sound Transmission Loss Test Results (ASTM E90)
Figure 2. Sound Transmission Loss Test Results (ASTM E90)

We are evaluating various commercial markets for this material including: construction in apartments, office spaces, and industrial applications.

For example, sound damping screens in welding areas that would also have FST properties are straightforward applications where roll-in screens can be used to reduce sound and risk of fire.

NOTES
(b) – Specimen TL within 10 dB of facility flanking limits.  No correction applied.  Value represents lower bound of specimen TL in this band.
(c) – Specimen TL corrected for sound transmission through laboratory filler wall per ASTM E90-09 (2016) Section 7.3.1.6
(d) – Specimen TL too close to laboratory filler wall.  Specimen TL corrected per ASTM E90-09 (2016) Section 7.3.1.7.  Value represents lower bound for TL in this band.
(e) – Uncertainty in this band exceeds limits of ASTM E90-09 (2016) Section A2.2.

 

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