The motion of the valve or valves in a shock absorber or strut controls the damping of the device. Practical Fluid Structure interaction in AcuSolve was used to simulate the valve deflection based on 13 mode shapes computed by NASTRAN. The figure below shows the schematic of the piston and valve area of the shock or strut.
Below is the overall computational fluid model. The oil enters through the lower annulus, passes through the ports in the piston, and pushes against the bottom surface of the valve. Higher pressure on the bottom face of the valve causes the outer portion of the valve to deflect upwards.
The computational domain consisted of 900,000 fluid elements and was run with a time step of 1.0e-6 seconds for 4000 time steps for a total of 0.004 seconds of run time. Click on the figure below to view animated streamlines and the valve deflection (1.4 MB).
The figure below shows the inflow velocity time profile in meters per second with a maximum of 0.5 m/s.
The following figure shows the vertical displacement at the edge of the valve. Note the overshoot phenomenon near 0.5 msec. The initial gap (zero displacement) is 0.01 mm and the final gap is 0.117 mm (0.107 mm displacement).