Reptilian Skin as a Biomimetic Analogue for the Design of Deterministic Tribosurfaces

Abstract

A major concern in designing tribo-systems is to minimize friction, save energy, and to reduce wear. Satisfying these requirements depends on the integrity of the rubbing surface and its suitability to sliding conditions. As such, designers currently focus on constructing surfaces that are an integral part of the function of the tribo-system. Inspirations for such constructs come from studying natural systems and from implementing natural design rules. One species that may serve as an analogue for design is the Ball python. This is because such a creature while depending on legless locomotion when sliding against various surfaces, many of which are deemed tribologically hostile, doesn't sustain much damage. Resistance to damage in this case originates from surface design features. As such, studying these features and how do they contribute to the control of friction and wear is very attractive for design purposes. In this work we apply a multi scale surface characterization approach to study surface design features of the Python regius that are beneficial to design high quality lubricating surfaces (such as those obtained through plateau honing). To this end, we studied topographical features by SEM and through White Light Interferrometery (WLI). We further probe the roughness of the surface on multi scale and as a function of location within the body. The results are used to draw a comparison to metrological features of commercial cylinder liners obtained by plateau honing.

Preliminary investigation of the frictional response of reptilian shed skin

“…The shortest spacing (approximately 3.5µm) was roughly located within the non-load bearing portions of the body (i.e. ; the head and tail sections) [13]. Using the dimensions of the fibrils it is possible to estimate the Fibril Aspect Ratio, FAR, from equation (1) as 1.5<FAR<2.4.…”

Layered patterns in nature, medicine, and materials: quantifying anisotropic structures and cyclicity

“…Additionally, analyzing layer morphology is an essential element of solving many problems in materials science, biomimetic, and forensic research. For instance, biometric research has explored the structural properties of butterfly photonic systems (Vukusic & Sambles, 2003), flower surfaces (Barthlott, Mail & Neinhuis, 2016; Huang, Hai & Xie, 2017), and snake skin (Abdel-Aal & Mansori, 2011; Klein & Gorb, 2012; Filippov & Gorb, 2016). In materials science, a material’s mechanical and physical characteristics are determined by its microstructure, which in many instances is layered (Moya, 1995; Mayer, 2005).…”

On the comparative cutting performance of nature-inspired structured cutting tool in dry cutting of AISI/SAE 4140

“…As such, one of the species that serves as an analogue for these requirements is ball python skin, specifically scales (Figure 1). 21 It was selected because this creature, when sliding against various surfaces does not endure much damage. It is reported 21 that such an effect stems from the asymmetric shape of the protrusion at the ridges of the skin scales.…”

“…21 It was selected because this creature, when sliding against various surfaces does not endure much damage. It is reported 21 that such an effect stems from the asymmetric shape of the protrusion at the ridges of the skin scales. The presence of micron and nano-sized fibril structures modifies the friction and adhesion during locomotion due to the minimisation of the contacting surfaces while maintaining optimal sliding performance.…”

“…This helps the snake to aid in shifting weight (contact load) and hence the contact angle (contact area) upon sliding. 21 Ball python skin has two principle layers: dermis and strata. Dermis is the deeper skin layers with rich supply of blood vessels and nerves while strata is closely pack cells forming the outer protecting coating.…”