Noise Control Solutions

DTI’s proprietary Stand-Off Damping Systems provide extremely high levels of damping performance while being weight-efficient and easy to install. Our systems suppress noise, vibrations, and high-cycle fatigue damage due to resonance response. We deliver superior levels of structural damping – especially relative to temperature – with minimal weight addition.

Common applications include aircraft fuselage skin, aerospace structures, marine hulls, and heavy off-road equipment.

DTI’s Constrained Layer Damping Systems vary from relatively simple designs for consumer appliances to multi-material designs for extended operating temperature ranges to very complex, lightweight designs for aerospace applications. Regardless of the application, our Constrained Layer Damping Systems are flexible, meet flammability and outgassing requirements, and can utilize a wide variety of materials –  including steel, aluminum, titanium, and carbon fiber composites.

DTI’s unique Damping Links are extremely effective for attenuation of a resonance response.  Our design and analysis approach allows us to locate the links according to the modal displacement of the structure in order to induce the strain into the viscoelastic material and not the structure.

DTI’s Tuned Vibration Absorbers are a cost-effective solution for situations when a noise or forced-vibration issue occurs for a single frequency. While TVAs have been used for many years in noise and vibration applications, there have been performance limitations and high installation costs associated with this approach. DTI has solved these problems with advanced manufacturing technologies. Our proprietary TVAs are designed to stay “tuned” across a wide range of operating conditions and harsh environments. Also, the manufacturing methodology eliminates the need to tune each TVA by hand, thereby decreasing costs and enabling use of full arrays of TVAs, when required.

DTI’s De-Coupled Mass Acoustic Barrier system consists of a mass layer that is decoupled from the base structure with a compliant spacer layer. The resultant solution creates a double-walled effect which improves performance at mid-to-high frequencies without a significant mass addition.  The system performs better at high frequencies than a single-walled system of the same mass.  Our Decoupled Mass Acoustic Barrier system provides a lightweight solution to significantly attenuate high frequency acoustic energy.

Turbo-prop aircraft typically are louder – and exhibit significantly more vibration – than jet aircraft.  In this particular case, the aircraft was being developed as a business aircraft, so it was extremely important that the turbo-prop noise and vibration be minimized.  The key goal for the project was to achieve interior sound pressure levels similar to a typical jet aircraft.

DTI designed and produced pre-cut kits consisting of an array of Tuned Vibration Absorber (TVA) units, which were then applied to a number of fuselage skin bays in the aircraft. The TVAs were located at approximately the center of the bay where bay stiffness is minimal and arrays were tuned  for 2ndBPF effects. Each TVA weighed only 0.17 lb.

The TVAs were installed in tandem with a special DTI  K1405 Standing Off Damping System, having a “tall” Stand-Off  Layer which was also applied to the aircraft fuselage  skin for enhanced stiffness (to minimize forced vibration from BPF events) and attenuation of turbulent boundary layer noise. The TVAs screwed onto a TVA mount (about the size of a U.S. quarter) that was bonded to the fuselage skin via quick-cure structural adhesive.  The SODS parts were cut with an access hole for the TVA mount.  The TVAs included a cover assembly designed to protect the TVAs from interference from thermal acoustic blankets or wiring harnesses, etc. in the aircraft.

The TVAs were injection-molded using a proprietary DTI VEM displaying very stable properties with respect to temperature. This approach ensured that the TVAs remain tuned as temperature fluctuates during the aircraft flight envelope.

Sound pressure level goals for the aircraft were achieved.  The TMD array yielded (-5 dBA) benefit  for 2ndBPF @ 200 Hz. The SODS  yielded (-3.0 dBA) benefit for TBL  noise > 300 Hz.

Crucial to this project was DTI’s ability to economically manufacture the TVA units already-tuned, which alleviated the need for expensive manual tuning.  DTI’s know-how  in terms of VEM selection, control of the dynamic mechanical properties of our VEMs, as well as our understanding of adhesion and general manufacturing experience, resulted in a very successful countermeasure.