PURPOSE The authors applied a novel microindentation technique to characterize biomechanical properties of small ocular and orbital tissue specimens using the hertzian viscoelastic formulation, which defines material viscoelasticity in terms of the contact pressure required to maintain deformation by a harder body. METHODS They used a hard spherical indenter having 100 nm displacement and 100...

Ball-groove contact problems are often encountered in machine design. The analytical modeling of the resulting stress-strain behavior is however difficult, as it implies the necessity to deal with the non-linear Hertzian theory of point contacts. This work addresses the limits of applicability of the available analytical approaches for the calculation of ball-V groove couplings employed in ultr...

Anchorage-dependent cells such as smooth muscle cells (SMCs) rely on the transmission of actomyosin-generated traction forces to adhere and migrate on the extracellular matrix. The cellular traction forces exerted by SMCs on substrate can be measured from the deformation of substrate with embedded fluorescent markers. With the synchronous use of phase-contrast and fluorescent microscopy, the de...

Hertzian formulas are commonly used for the evaluation of deformation and pressure distribution non-conformal slightly conformal mechanical pairs to estimate component stiffness durability. For sake simplicity, their use is extended even those cases in which Hertz’s hypotheses do not hold. This paper summarizes theory compares results obtained with theoretical finite element analysis point cont...

Fracture modes in a model glass–polymer coating–substrate system indented with hard spheres are investigated. The large modulus mismatch between the glass and polymer results in distinctive transverse fracture modes within the brittle coating: exaggerated circumferential (C) ring cracks that initiate at the upper coating surface well outside the contact (as opposed to the near-contact Hertzian ...

The growth of transverse cracks under expanding spherical contact in a model system consisted of soda-lime glass bonded to a polycarbonate substrate is observed in situ from below or from the polished edge of the bilayer. Abrasion or chemical etching is employed on the coating surfaces to control the initial fracture. In the limit case of monoliths, the crack mouth becomes fully engulfed by the...

A lubricated contact suffers from starvation when the lubricant does not fill the contact inlet adequately. Such a situation arises due to short lubricant supply or at extremely high speeds. The starvation effect is modeled by shifting the position of the inlet meniscus towards the contact zone. The degree of starvation, so obtained, is plotted as a function of the position of inlet meniscus un...

The incremental compliances, normal and tangential, of an interface between rough surfaces are considered. Contacts are assumed to be elliptic – the shape of Hertzian contacts between any two locally smooth asperities. The ellipses may have diverse eccentricities and random or non-random orientation distribution; in the latter case, the tangential compliance is anisotropic. It is found that the...