Hits:
Indexed by:期刊论文
Date of Publication:2021-01-29
Journal:MICRO & NANO LETTERS
Volume:12
Issue:7
Page Number:439-444
ISSN No.:1750-0443
Key Words:drag reduction; skin; embossing; polymer films; moulding; rolling; rollers (machinery); numerical analysis; biomimetics; roller embossing process; shark-skin-inspired microriblet replication; riblet structure; shark skin; biological function; drag reduction; large-scale bionic shark skin surface; shark-skin-inspired microriblets; drag-reduction effect; negative microstructures; UV-LIGA technique; polyvinyl chloride; PVC; polyethylene terephthalate; PET films; polyethylene terephthalate
Abstract:The riblet structures of shark skin have a significant biological function for drag reduction, which has been verified. However, it is difficult to fabricate large-scale bionic shark skin surface with high precision and low cost. The real shark skin micro-riblets were first measured and approximately simplified to obtain shark-skin-inspired micro-riblets. Numerical simulations were performed to explore the drag-reduction effect of the micro-riblets surface. According to the simplified micro-riblets, a nickel mould with negative micro-structures was manufactured by Ultra-Violet Lithographie, Galvanoformung and Abformung technique. Roller embossing process was adopted to replicate shark-skin-inspired micro-riblets, capable of transferring the micro-riblets to polyvinyl chloride (PVC) and polyethylene terephthalate (PET) films. After embossing experiments, the effect of process parameters on roller embossing qualities including mould temperature, rolling pressure and rolling speed, evaluated by the depths of riblets embossed on the polymer films, were investigated. The results showed that the roller embossing process is a feasible and effective method to continuously replicate shark-skin-inspired micro-riblets on polymer substrates. Moreover, the optimal process parameters were determined, including mould temperatures of 70 degrees C (for PVC) and 60 degrees C (for PET), compression ratios of 1.22 (for PVC) and 1.53 (for PET) and rolling speed of 1 r/min.
