Strength Analysis Of Helicopter Rotor Blades Based On Fluid-structure Interaction

Helicopter rotor is not only the lifting device,but also the propulsion and control device.The Aerodynamic environment of helicopter rotor system is more complex than the fixed-wing aircraft,the blades is forced by gravity,lift,centrifugal force and inertia force,is the coupling of various geometric,structural,aerodynamic and inertial.Therefore,the analysis involving the rotor blades need to simultaneously explore the geometry and working environment.The Current analysis method of helicopter rotor blade strength mainly theoretical analysis,experimental measurements and finite element simulation.Theoretical analysis needed to make a variety of simplifying the processing,and the complex blade model is difficult to analyze;experiments are mainly static strength analysis,cross-sectional stiffness dynamic characteristics test and wind tunnel tests;The terms of the existing finite element simulation analysis on the blade structure,there are also studies rotor flow simulations,but the studies both involving flow field simulation and analysis of the blade strength is not enough.In this paper,by using multiple reference frame MRF method the helicopter hovering transient unsteady flow field calculation problem is simplified to a stable steady calculations problem.An efficient calculating algorithm for simulating helicopter rotor flow field is Established,get a reliable steady flow field results.Then building coupling between the flow field and the rotor blade structure and realize one-way fluid-structure interaction by using fluid-structure interaction approach,based on the ANSYS Workbench data transfer platform.And detailed analysis of the stress and deformation about several materials blades on the rotor flow field aerodynamic loads by the algorithms.Then analyzes the strength,and Compare results,find out the hazardous areas.This paper first analyzes the structure dynamic characteristics of helicopter rotor blades,establish dynamics model and numerical model of blade based on the rotating elastic beam theory.Then study the movable flow area problem,Establish numerical for calculating and analyzing of multiple reference frame method(MRF method)and sliding mesh method.The grid structure,turbulence model and boundary conditions in a large Mach number compressible flow selection is determined by a M6 wing model example.For further rotational symmetry rotor flow in the hover state,the coordinate system is built on the blade,use MRF method to simplify the problem in the rotating coordinate system for the steady state calculation,improve the computational efficiency of the hovering flow field.Then establish a rotor flow model with Caradonna-Tung rotor blades as the standard.For subsonic non lifting rotation and lift hover flight conditions,two grid models are established and meshed by used ICEM meshing,obtained the well quality of the grid structure.calculating Flow field by used pressure inlet and pressure outlet boundary condition,got a steady flow field results and are compared with experimental data,are in good agreement.Finally,study the implementation of fluid-structure interaction,analyze method of data transfer at the interface coupling and mismatched grid interpolation mapping,The load data is transfered between flow and solid by conservative interpolation method.To establish the isotropic metal material blade finite element model,were given structural steel,aluminum and titanium three materials parameters.Be fluid-structure interaction analysis,were calculated the force and deformation of blades in the case of three flight conditions as under subsonic pure centrifugal force rotation,no lift force rotation and lift hover.got dangerous regions of different materials and the stress concentration.Provides a reference for blade design.