Study On New Kind Of Gas Bearing Torsion Pendulum Used For Mass Property Parameters Measurement

Comprehensive test platform for mass property parameters (mass, center of mass,moment of inertia, moment of inertia) is the aerocraft important technical parameters ofsatellite, rocket, missile space.When some irregular shape of the object to be tested, center of mass and geometricdeviation is too large so that torsion pendulum appear tilt. It become serious whenexcessive bending and torsion bar structure, and the phenomenon of the fracture appear.It requires to increase the rigidity of torsional pendulum.Such as satellite requires high precision measurement, and because of shapestructure, it cannot offset or upside down, and can only be acquired by a clamping allquality parameters. It needs to be take adjustable table, centroid and torsion pendulumtogether. The centroid position of specimens in the vertical direction be confirmed by atilt; By measuring the specimen different position and status of the moment of inertia,set up simultaneous equations to calculate the moment of inertia of the specimens. Thiscomprehensive test platform must be limit in the vertical direction, because the axialsize of comprehensive test platform is bigger.Traditional torsion pendulum uses angular contact ball bearing as the supportstructure, and uses the structure of torsion bar as torsional vibration structure, whichaxial size is long. To improve torsion pendulum anti-overturning moment, increasingthe bearing radial size and increasing the frictional resistance at the same time, lead tofast attenuation of torsion pendulum vibration cycle, moment of inertia measurementaccuracy is lower than0.5%. Obviously, the traditional torsion pendulum does not meetthe requirement of comprehensive test platform.To solve these problems, the traditional torsion pendulum angular contact ballbearing is replaced by air bearing, converting mechanical friction resistance to airresistance, and damping coefficient is about0.003, the measurement accuracy up to0.1%. By increasing the distribution of the orifice radius, the ability of torsionpendulum anti-overturning moment is improved, and the fracture phenomenon oftorsional vibration system is reduced. For the size of the comprehensive test platform inthe vertical direction is too large, using a cross-shaped spring block structure to replacetorsion bar structure, and the axial size shortened. the capacity and anti-overturningmoment characteristics of torsion pendulum is analyzed. The gas bearing geometry parameters and the relationship between bearing capacity and the characteristics ofanti-overturning moment is studied. Through the numerical simulation and experimentverify the validity of the measurement model and calculation method. Finally theexperimental results show that the improved test platform improves the measurementprecision and the stability of vibration. It has an important significance for the satelliteaerocraft quality characteristic parameters.