variation of the hysteresis central line graph showing variation of the mean pressure versus the piston stroke when the maximum working pressure of the colloidal damper 1 is set to 20 mpa 25 mpa 30 mpa 35 mpa 40 mpa and 60 mpa accordingly the internal spring constant k s of the colloidal damper 1 is calculated by multiplying the cross sectional area of the piston 4 by the slope of the central line of the hysteresis as illustrated in fig8 a fig8 b illustrates the relationship between the maximum working pressure and the internal spring constant of the colloidal damper 1 from fig8 b one observes that the internal spring constant linearly increases at the augmentation of the maximum working pressure both in the regions of low and high values of the maximum working pressure this can be explained by the fact that the working liquid 8 does not flow into and flow out from the pores of the porous bodies 9 in these regions and consequently only the compressibility of the working liquid and the elasticity of the sealing device are responsible for the observed variation of the internal spring constant in these regions additionally one observes that when the maximum working pressure varies in the range of 15 to 45 mpa since the working liquid 8 flows into and flows out absorption and desorption from the pores of the porous bodies 9 the stiffness of the colloidal damper 1 decreases namely the internal spring constant decreases for a given maximum working pressure the mean pressure can be calculated based on fig7 b which provides the relationship between the mean pressure and the maximum working pressure of the colloidal.