Effective contact modulus and fluid load fraction from indentation at 7.7 µm/s. Effective contact modulus (a) and fluid load fraction (b) did not vary significantly with indentation depth, contact radius or force during non-equilibrium indentation (depth, contact radius, and force are interdependent). The equilibrium contact modulus, Ec0, is shown for reference (a). Agbezuge and Deresiewicz, 1974, predicted the limiting Hertzian contact response for a linear poroelastic material (a, b).