PSI - Issue 35

Gaston Haidak et al. / Procedia Structural Integrity 35 (2022) 124–131 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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The second part is the experimental model made using a new design of the test rig. The test is made to measure the fluid film thickness, fluid pressure distribution and temperature between slipper and swashplate, which will then be compared to the simulation results. The combination of measurement and simulation help to better understand the behaviour of the fluid (lubricant) behaviour to understand the mechanism better and predict the damage and failure between the slipper and the swashplate. The test rig is presented in Fig. 3. The notations (A) and (B) represent the installed rig test in the laboratory and its 3D model, respectively. (1) indicates the slipper, (2) the swashplate, (3) the piston, and (4) the cylinder block. Finally, (C) indicates the output data (results). Here, the rotor is the swashplate-shaft assembly, and the stator is the cylinder block.

Fig. 3. Measurement environment.

The experimental test methodology is as follows: three displacement sensors and three temperature sensors are inserted into the slipper pad. The displacement sensors (03) are inserted in a separated point at an angle of 120°, similarly for the temperature. Since the system is designed for operation under normal pump conditions, rotational speed and loads are applied. Subsequently, parameters such as speed and loads are varied to collect data in order to

analyse the fluid’s behaviour. 3. Results and Discussion

During the normal working operation of the axial piston pump, the pressure forces transmitted from the pressure chamber to the slipper/swashplate interface by the piston vary periodically. From 0 to 180 degrees, it is the pressurised zone (high-pressure zone), and between 180 and 360, the discharge zone (low-pressure zone). The estimation of the load applied under each slipper, in this case, is calculated following the slipper carrying loads discussed in (Haidak et al., 2019a). The simulation is therefore done while taking this into account in Abaqus. The pump used here is the one with nine pistons (9 slippers as well). Fig. 4 shows, from left to right, the pressure distribution, deformation and the correspondent fatigue of the swashplate. We can notice that the intensity of the pressure on the swashplate (initially applied pressure is 40 bar). This is because the area exposed to damage and failure is located by the swashplate’s internal edg e, and it is more propagated by the higher-pressure zone. The swashplate angle control movement in its turn influences the uniformity of applied load. It leads the total applied load to be more in the swashplate control direction. Fig. 5 presents the deformation of the slipper and its related fatigue, which is exaggerated by the external edge of the slipper pad. The micro-dynamic motions of the slipper on the swashplate can explain.