For over thirty years, DTI has delivered lightweight noise and vibration control solutions with proven results in complex applications and extreme environments found in commercial aircraft, private jet, spacecraft, satellite, and defense applications.
Aircraft Noise Reduction
DTI's world-renown passive damping solutions are trusted by major aviation manufacturers to enhance comfort for passengers and crew.
Commercial & Defense Structural Integrity
Our solutions extend structural integrity for aircraft and spacecraft, preventing structural failure caused by damaging vibrational energy.
Spacecraft &Satellite Solutions
Our products enhance structural design of satellites and spacecraft, protecting crew and sensitive instrumentation from harmful vibrations.
CASE STUDY: Aircraft Fuselage Skin
Turbulent boundary layer noise is caused by excitation of resonance response of aircraft fuselage skin panels typically in the 500 Hz to 4000 Hz frequency range, which is near the sweet spot for human hearing. Some of those resonances are very profound in terms of acoustic radiation efficiency.
Fuselage skin typically exhibits fairly low levels of damping and those panels also have significant area, which makes them particularly efficient for acoustic radiation.
In this application, there is no better countermeasure for resonance response than damping. The application site temperatures at cruise range from (-30 F) to (-20 F) in a nominal business jet aircraft – and often from (-15 F) to (0 F) in large commercial transport aircraft.
DTI designs its passive damping systems for fuselage skin applications via FEA model, which includes the effects of curvature and of pressurization (including induced hoop stresses).
DTI’s Stand-off Damping Systems are proven to aid in attenuation of resonance response in fuselage skins in a wide variety of aircraft and under extreme operating conditions.
Instead of a one-size-fits-all approach, it can be beneficial to utilize higher-performance passive damping systems in areas where the fuselage skin is subjected to increased excitation. Wing box areas or the crown of the aircraft are examples.
DTI’s FEA design tools allow for optimization based on partial coverage strategies that minimize added weight.
Case Study: Special Weapons Aircraft
This special weapons aircraft was designed to destroy ICBM missiles in the lift phase via a nose-mounted laser. Two different aeropace industry customers asked for DTI’s involvement in the project. A vibration control countermeasure was required for the fuselage skin aft of the laser turret to mitigate potential HCF failure of the skin which was exposed to excessive wind buffeting due to the relatively poor aerodynamics of the laser turret. Because of stability requirements needed for the laser turret (related to targeting), a passive damping system was required for the very thick honeycomb composite bulkhead installed in the nose of the aircraft to support the laser turret. Finally, a passive damping system was designed and applied to the laser turret skin to enhance laser stability.
DTI designed a unique Stand-Off Damping Systems (SODS) for each of the applications. Simple closed-form solution RKU-based models were utilized to represent each of the panel-like structures.
The extremely thick bulkhead structure (about 4” thickness with carbon fiber composite facing sheets) was particularly challenging for DTI engineers. The SODS designed for the bulkhead utilized a carbon fiber composite constraining layer as did the SODS designed for the laser turret skin. Operating temperatures at the application sites were accommodated via proper selection of DTI VEM damping materials via RKU model and experimental iteration.
Originally, the special weapons aircraft was slated for production and USAF fleet status. However, the program was eventually downgraded to “test platform status”. In test platform status, the aircraft successfully shot down ICBMs in the lift phase, as designed.
Correlation between DTI model predictions and experimental data acquired on representative test articles was excellent.
CASE STUDY: Aircraft Trim Panel
The customer contacted DTI regarding attenuation of resonance response of aircraft trim panel structure in business jet applications. Resonance response of the trim panels were shown to contribute to the unwanted noise, because trim panel isolator mounts cannot be made soft enough to isolate the trim panels well from the airframe due to hard landing requirements. The trim panels consist of relatively thin Nomex honeycomb composite with fiberglass facing sheets.
Because the trim panels are utilized as an acoustic barrier mechanism, the customer asked for a hybrid system including a lightweight constrained layer damping system (CLDS) in combination with a de-coupled mass acoustic barrier. Application site temperatures range from (+50 F) to (+70 F) during cruise.
DTI designed (2) Stand-Off Damping System versions for the application. Each SODS induced modal loss factor well in excess of (n = 0.10) for the (+50 F) to (+70 F) temperature range. The SODS utilized aluminum constraining layers.•(2) SODS were configured. The heavier SODS utilized a thicker Stand-Off Layer.
The CLDS + DCM acoustic barrier yielded very high levels of attenuation of the FRF compliance of the aircraft trim panels. •The decoupled mass (DCM) acoustic barrier system, in conjunction with the lightweight CLDS provided very high acoustic transmission loss performance. Flight tests revealed excellent performance with the SDODs installed on the aircraft trim panels.