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Stainless Steel Braided Reinforced Teflon Hose（SSBRTH), as an extensively used component in the aviation hydraulic system, has a huge impact on system performance. Because of its elasticity, the calculation of hose deformation and capacitance is difficult, and inappropriate hose parameters likely degrade the system and even affect the aircraft’s normal operation. In this study, the theory of corrugated plate is introduced for deformation prediction of fluctuant steel wire, then a new analytical model is established to describe the deformation condition of each regular braided SSBRTH layer with its capacitance calculation. In addition, the immediate establishment of SSBRTH 3D models by Rhino & Grasshopper parametric modeling for FEA is proposed and compared with the analytical model of capacitance, whose accuracies are all verified by experiments. The results emphasize that the actual deformation of the hose was in accordance with the prediction, and steel wire diameter, braided angle and the number of steel wires are negatively correlated with the capacitance value.

Pressure pulsation is the challenge in digital hydraulics owing to its switching characteristics, which makes control performance worse. This study proposed the parallel-series structure for active pressure pulsation suppression, based on variable step size FXLMS algorithm. The pressure pulsation performance in DFCU is analyzed under PNM and PWM control for better suppression effect. On this basis, the active pressure pulsation suppression control algorithm is designed utilizing the principle of pressure wave destructive interference, so that the reverse pressure pulsation generated by the parallel-series structure, including an in-series valve arranged in line between the DFCU and the load and a by-pass valve arranged in parallel with DFCU, offsets with the pressure pulsation at the load end. The adaptive FXLMS algorithm with variable step size is used to identify the secondary path online for better effect of pressure pulsation suppression and achieve the “alignment” between the reverse pressure signal and the initial pressure signal. The experimental results show it can suppress pressure pulsation by 79%, 54%, 37% and 29% at 10 Hz, 30 Hz, 50 Hz, 70 Hz for single valve and 77% for DFCU. It has been demonstrated that the proposed structure has significant effect and guiding relevance for pressure pulsation suppression of DFCU.