Time-domain Identification Of Distributed Dynamic Load On Helicopter Rotor Blade Model

As the main source of the helicopter vibration, dynamic load on helicopter rotor has become one of the core issues that seriously influence the performance and development pan of helicopter. To get the dynamic load on rotor is the premise and foundation to formulate and implement the solutions of helicopter vibration control. Based on the theory of orthogonal polynomials, the distributed dynamic load on helicopter rotor blade is determined in time domain.Distributed dynamic load identification belongs to the second class of inverse problems in the structural dynamics field, with considerable difficulty. Based on the theory of two-dimensional generalized orthogonal polynomial, the function of dynamic load is fitted by the orthogonal function. The identification of distributed dynamic load can be transformed into the solving of the fitting coefficients. According to the structure feature of the rotor blade, the equivalent model of rotor is established. The dynamic load distributed on the blade model can be assumed as continuous distributed cyclic load and fitted by generalized orthogonal function. The dynamic response of the rotating blade excited by orthogonal function force is calculated to achieve the dynamic calibration of the distributed dynamic load. And the time domain identification model based on the limited dynamic response measurement is established.Based on the equivalent model of helicopter rotor, this thesis studies the impact of varying degrees of noise contained in the measured response on the result of load identification by simulation. The simulation result shows that the identification of distributed dynamic load on helicopter rotor blade is theoretically feasible, and it has good noise immunity.Through the helicopter rotation rotor test, the distribution dynamic load on the helicopter rotor blade model is determined in time domain. The test results verify that time-domain identification of the distribution dynamic load on the helicopter rotor blade based on two-dimensional orthogonal polynomial is feasible in engineering practice.