SBIR-STTR Award

Rotors and their associated dynamic components operate in high-cycle and environmentally harsh conditions. Accurate rotor load predictions are crucial part of rotor analysis and design. Lag damping poses a challenge for rotor load analysis due to the difficulty of incorporating lag damper effects into comprehensive rotor analysis. The key challenge in effectively predicting the lead-lag motions and resulting rotor loads is the lack of a high fidelity lag damper model. A high fidelity lag damper model that can predict damping forces over the operational range of a helicopter will benefit future rotor designs.

Benefit:
This lag damper analysis system will have broad application to both civilian and military helicopter systems.

Keywords:
Semi-Active, Semi-Active, lag damper, damping, stiffness, lag damper modeling, passive

The primary goal of this STTR program is to develop high fidelity LDLP software module that can predict stiffness and damping forces over the ranges of amplitude, frequency, and temperature appropriate for comprehensive modeling of helicopters. The LDLP module will focus on enabling accurate prediction of the onset of both air and ground resonance, as well as the fatigue loads that would arise due to the implementation of such lag dampers, and the impact of fatigue on the Remaining Useful Life (RUL) of rotor and rotor hub components. This project will develop a software module that provides the capability to predict lag damper behavior, especially the stiffness and damping forces that arise from lag dampers of varying configuration, material choices, fluid properties, and feedback control strategies in the case of semi-active or active lag damper technologies. The project team will construct an LDLP software module that will be configured to interface with any existing comprehensive rotorcraft analysis code, such as the University of Maryland Advanced rotorcraft Code (UMARC), Copter (Bells comprehensive rotor code), CAMRAD II (Comprehensive Analytical Model of Rotorcraft Aerodynamics and Dynamics), and GenHel (Sikorskys General Helicopter Flight Dynamic Simulation Model).

Benefit:
This STTR program enhances the effectiveness and accuracy of current rotor load prediction tools. Producing a reliable and accurate rotor load prediction system is particularly attractive for rotorcraft, fixed-wing aircraft, unmanned aerial vehicles, and other application areas where similar problems exist. Key benefits and payoffs of the proposed technology are: Development of comprehensive lag damper models of different type and configuration that can forecast damper performance and enhance optimal damper design; Development of a compact, all inclusive lag damper load and performance predicting software module that is analytically and experimentally validated; Integration of lag damper modeling suite, coupled with advanced finite element methodology for improved predictions of rotor loads, overall hub forces, and structural response; Improved load prediction of rotor system and benefits to conducting failure mode analysis and condition based maintenance (CBM).

Keywords:
hydromechanical modeling, Elastomeric, Semi-Active, damping, Magnetorheological, air and ground resonance, load prediction, stability, stiffness, hydraulic, Lag dampers, Fatigue