Research On The Testing Mechanism Of The Self-lubricating Spherical Plain Bearing Of The Helicopter Swashplate

The helicopter swashplate is the critical component of helicopter control system, andits pose will be changed by the pilot handling control column, with the performance ofcyclic pitch and collective control, then helicopter can fly forward, backward, left andright. Self-lubricating spherical plain bearing is the most important part of the helicopter,which is also the pivotal component to change the pose of swashplate. With the purpose ofproviding a theoretical reference to design the spherical plain bearing testing machine,researches on the working principle of spherical plain bearing and testing machine modelhave been carried out.Based on the analysis of the working principle of helicopter swashplate, thekinematic mobility of spherical plain bearing is obtained, and type synthesis of theenforcement mechanism is accomplished. The equivalent loading mechanism is proposedfrom the structure of up swashplate mechanism. Consequently, the spherical plain bearingtesting mechanism is a hybrid parallel-parallel mechanism dynamically connected by arolling bearing.Then the kinematic analysis of the hybrid mechanism is carried out, including thedegree of freedom, position analysis and the workspace. The first order kinematicinfluence coefficient matrix and the second order kinematic influence coefficient matrixare established using the method of virtual mechanism. The velocity and accelerationcurves obtained by using differential method and influence coefficient methodrespectively are consistent with each other, that has verified the validity of the kinematicinfluence coefficient matrix.The loading transmission model of swashplate mechanism is given based on theactual mathematical model of the blade hinge moment of helicopter in steady flight status,with the loading transmission characteristic of pitch link to be taken into account. Basedon the model of helicopter swashplate mechanism, the relational expression between theloading of hydraulic booster and the blade hinge moment is expressed, as well as the loading of spherical plain bearing.The3D simulation model of the spherical plain bearing testing mechanism is built byusing SolidWorks, and then simulated by ADAMS. The velocity and acceleration curvesof the hybrid mechanism are obtained, in accordance with the theory results.