The Equivalent Modeling Method Of Helicopter Based On Structural Dynamics

The aircraft is made of thousands of structures and it also has a huge number of DOF. In order toavoid complex calculation, we should try our best to reduce the DOF of the structure during themodeling stage, so finding an accurate and effective method to make an equivalent model is necessary.The method of energy equivalence was used to make a helicopter model of multiple DOF equivalentsto a beam element in space, the stiffness and inertia characteristics of the equivalent beam werederived, and the total stiffness matrix and mass matrix were obtained by using the finite elementmethod. And then we can get the equivalent model which made of beam and shell through thestiffness matrix and mass matrix we obtained above, which reduce the DOF of the original structure.This paper was mainly focused on how to using the method of energy equivalence to simplifymodel accuracy. By using this method, we simplify a helicopter model to a combined model of beamand shell, and then we use Patran to calculate the modal of each model, and moreover, we make acontrast of the modal. At last we can judge the model by the result of the contrast of the modal. Afterwe get the equivalent model, we make a scaled model which size is the half of the original modelbased on the similarity theory. Then the same contract was made to judge the model.At last, genetic algorithm is used to optimize the model. According to the final model, we make asummary of each model and each method.