The force test platform was coupled flexibly with the fixed air pipeline with stagnation points based on the mechanism of force balance

and analysed deeply in order to explore the relationship of elastic bellows and internal flow six-component force-measuring balance in nozzle test facility.The changes of balance output signal connecting expansion joints and added force of balance control body by pressure were compared under the principle of load distributed by stiffness

and this was investigated to match the expansion joint stiffness and effective area with the force test platform.The test results indicate that the effect of elongate fixing of expansion joints with stagnation point is evident

the coherence of effective area of expansion joints must be very good

and the whole lateral stiffness must be smaller especially in order to reduce the excursion of benchmark stagnation point of balance and increase the aerodynamic stability of the force measurement system.