Structure Design And Analysis Of The Dynamic Stiffness Test System For Rudders

As an significant component of the aircraft’s control system, rudder’s performancedirectly influences the aircraft’s operational characteristics. Its dynamic stiffness reflects itsability of resisting deformation brought by the external loads in its practical working processand can be tested using the dynamic stiffness test system under different external load withvarious frequencies. The test results can provide important basis for improving the rudder’sdynamic characteristics and stability, and hence prevent the occurrence of the flutter andflight accidents.This thesis analyzes the relevant researches about the dynamic tests of the rudder, andsummarizes the test principles and specific methods. Then based on the technical demands,a novel test system is proposed. Referring to the available structures of the rudder testsystem, this thesis develops a novel structure which can position repetitively in the threedegrees of freedom.The key components are calculated and choosen. Then the3D model ofthe test platform is built. Through analyzing the loading methods, direct output and indirectoutput plans are compared and finally the twin type motor is choosen to act as the actuator.Finite element analysis is conducted on the system to test its static and dynamiccharacteristics.Based on the modal analysis results, the structure is further improved tofulfill a higher first-order modal frequency and hence avoid the resonance. Finally, the staticanalysis and fatigue analysis are conducted on the key components. The analysis resultsshow the design can meet the requirements.The dynamic stiffness test system can be used to test different rudders providingtorques with maximum40Nm and120Hz and can achieve the coaxial alignment betweenthe rudder shaft and drive shaft.