Optimization design and pressure regulation method of the ultra-large flow accumulator group for multiple function loading system

To meet the test requirements of the key structural part in the super high-rise building, a 108MN 6-dof advanced structural testing system is developed. And for the high-speed shear test of the large rubber bearing, the instantaneous flow demand of the testing system is far more than the conventional hydraulic testing equipment. For this, the piston accumulator group with the separated nitrogen cylinder is adopted as the system auxiliary hydraulic power. In the paper, the optimization design of the accumulator group is implemented though continuously optimizing the volume ratio of the accumulator and the nitrogen cylinder. And when the accumulator group works, its pressure decreases from the precharge pressure to the working pressure constantly, which will impact the loading accuracy, and the excessive pressure is also not conducive to the protection for the specimen. To restrain the pressure fluctuation, a pressure control loop with the large-flow cartridge valve is presented, the associated model is set up and the control method is developed. The results show that with PD control the oil supply pressure of the accumulator group can be stabilized within the required range, and the control precision is high.