Depth-dependent hysteresis in adhesive elastic contacts at large surface roughness

Abstract

Contact force–indentation depth measurements in contact experiments involving compliant materials, such as polymers and gels, show a hysteresis loop whose size depends on the maximum indentation depth. This depth-dependent hysteresis (DDH) is not explained by classical contact mechanics theories and was believed to be due to effects such as material viscoelasticity, plasticity, surface polymer interdigitation, and moisture. It has been observed that the DDH energy loss initially increases and then decreases with roughness. A mechanics model based on the occurrence of adhesion and roughness related small-scale instabilities was presented by one of the authors for explaining DDH. However, that model only applies in the regime of infinitesimally small surface roughness, and consequently it does not capture the decrease in energy loss with surface roughness at the large roughness regime. We present a new mechanics model that applies in the regime of large surface roughness based on the Maugis–Dugdale theory of adhesive elastic contacts and Nayak’s theory of rough surfaces. The model captures the trend of decreasing energy loss with increasing roughness. It also captures the experimentally observed dependencies of energy loss on the maximum indentation depth, and material and surface properties.

Magnetic Properties, Adhesion, and Nanomechanical Property of Co40Fe40W20 Films on Si (100) Substrate

“…The increased surface roughness can lead to the pinning effect of the domain wall, which is not easy to move, resulting in the increase in coercivity [40,41]. Moreover, the rough surface roughness can be induced high surface energy, causing a high adhesion [42,43]. This result is consistent with Figures 4 and 9. 3.5.…”

Adhesion Hysteresis due to Chemical Heterogeneity

“…As an example, in Fig. 5 results are shown, which have been obtained experimentally in the papers [17][17], [18]. Experiments were carried out by indenting a glass ball against a plane PDMS substrate and subsequent pulling it off.…”

“…5 Experimental loading-unloading curves (adapted from the paper [17]). According to [17], curves were measured using AFM for contacts between a glass sphere and a PDMS substrate. The glass sphere was of diameter ≈50 μm.…”

Influence of Tangential Displacement on the Adhesion Force between Gradient Materials

“…Such conditions are very often reproduced in experiments studying the adhesion, when the indenter is moved by means of an external drive characterized by a much higher stiffness than the adhesive contact itself. This configuration makes it possible to study contact phenomena in the quasistatic regime, when the drive velocity is very low and a stationary contact is realized at every time moment [24,25]. This is the case where the JKR theory [18] is valid.…”