Squeeze lubrication between soft solids: A numerical study

Effect of bionic hexagonal texture on squeezing films inside soft contacts with high adhesion and high friction

“…10, distinguishing the effect of PDMS viscoelasticity on the squeezing film thickness distribution is challenging. According to previous numerical results, 36 during the squeeze process, the contribution span of the viscoelastic effects on the film thickness distribution manifests in a short time of approximately 0.01 s, while the frame rate of the ordinary CCD in the present test rig range from 20 Hz to 70 Hz, which is incapable of capturing the instantaneous viscoelastic phenomenon in the fluid film thickness distribution in a similar time scale. In addition, in the seconds time scale in Fig.…”

“…10, the material has enough time to relax, and the viscoelastic case approaches the elastic behavior. According to the EHL squeeze film theory, at this stage, the pressure distribution tends to the classical Hertzian-like solution, 36 demonstrated by the measured film thickness distribution at a time of 1 s.…”

“…Note that the solid viscoelasticity can affect both the fluid film thickness and the pressure distribution, affecting the capacity to predict the behavior of soft systems under lubricated conditions. 34 Regarding the pressure and film thickness distributions under non-steady-state squeezing conditions, recent numerical investigations 35,36 found that two timedependent processes of the flow squeeze and viscoelastic relaxation significantly deviate the lubrication regime from the classical EHL solution. In particular, the pressure distribution shows two peaks at the contact area borders, where the film thickness presents two ridges.…”

On the Role of Roughness in the Indentation of Viscoelastic Solids

“…Sliding motion has been widely studied due to its applicative importance and, in particular, to the so-called viscoelastic friction: the latter is related to the periodic deformation occuring during the sliding mechanics and is shown to be dependent on the entire roughness spectrum. To this extent, numerical calculations have qualitatively corroborated what was predicted on analytical basis by Persson's theory [1] and have generalized the analysis to different geometries, including thin layers [31], to several kinetic conditions, including the reciprocation of rough solids [31], and also to biphasic interfaces, with a number of studies enlightening the so-called visco-elasto-hydrodynamic regime [32][33][34][35].…”

A Review on Modelling of Viscoelastic Contact Problems

“…The numerical approach was later generalized by Putignano [146] to take into account different contact configurations and to investigate the effects of viscoelasticity in each case. The latest work of Putignano and Campanale [147] extended the study of VEHL contact to non-steady-state conditions, where a strong coupling between the time-dependent features of the fluid-dynamics problems and the viscoelastic relaxation of the material was found. A point VEHL contact model was recently developed by Zhao et al [148].…”