Development On Thrust Vector Measuring Platform For Rocket Motor Thrust Vector Measuring System

Rocket motor thrust rector is space vector and the practical thrust functionary line deviates from theory axis of motor nozzle. The thrust vector parameters, such as thrust offset 8 and misalignment angle α ,can describe the motor thrust misalignment and it is the important estimation indices of rocket motor properties. Because of the random variation of the motor thrust misalignment, it is very difficult to be measured accurately. The devices, such as multi-component measurement table and thrust vector measurement rotating table, are used frequently, but they are suitable only for steady test of the thrust misalignment, especially it can't do very well when some load is very high and other loads were low. The paper introduces piezoelectricity quartz thrust vector measuring platform and its measuring system, which is suitable for static and dynamic multi-component measurement because of its better static rigidity, higher sensitivity and natural frequency.Firstly, measuring principle of the thrust measuring system is introduced, and how to select the design schemes of static calibration. The measurement system is made up of 4 three-component piezoelectric force transducers. Used the output of each force transducer, the thrust vector eccentricity parameters can be calculated by some deduced expressions. It is considered that the reasonable selection of static calibration device is the key factor to ensure the precision. After the design and experiment of different schemes are used, hydraulics function load model on the tension is selected.Secondly, based on the static analysis using finite element software ABAQUS, the structures parameters optimum design of measuring platform is carried to reduce unlinearity and get minimal cross talk. The experiment results testify better quasistatic property index .The sensitiveness and linearity of measuring platform all can completely meet the design needs, and the natural frequency on the direction of main thrust is higher than 1KHz,and it can satisfy the need of thrust vector dynamic measurement.Finally, a decoupling algorithm method is made for the measurement of thrust vector based on the analysis of the mathematical model of measuring platform. The decoupling among three-dimensional thrust is reduced and testing precision is improved. To verify the measuring properties in random direction, the force is applied in the direction of coordinate axes and different quadrant with a specially designed thrust misalignment load device. The results of measurements show that thrust offset δ and misalignment angle α can be measured accurately and stably.