The Reduction of Static Friction of Rubber Contact under Sea Water Droplet Lubrication

Abstract

Abstract:In this work, a series of experimental tests is carried out in laboratory conditions which set the rubber compound (soft and stiff), the normal load, and the direction of propagation of sea water droplets into the interface of rubber-steel pipe contact as variables. The results show that the maximum static frictions (F) of rubber-pipe contacts increase as the normal load increases in both dry and lubricating conditions, and the values of F for the softer rubber are higher than that for the stiffer rubber. However, significant reduction in static friction is found due to the lubrication of sea water droplets. The influence of lubrication is stronger when the droplets propagate into the contact interfaces at the tail edge than that at the front edge. Capture sequences of the contact region facilitate the lubrication of seawater droplets by accelerating the progress of separation in the contact interfaces, thus reducing the static friction force. This investigation improves our understanding of the lubrication of sea water droplets during pipe-laying operation, and it will help us to conduct further research on the accuracy and safety of offshore engineering.

Fluid wetting infiltration characteristics and mechanical driving mechanism in rough rubber‐glass contact interface

“…Contact pressure, which has a direction effect on interfacial fluid infiltration, plays an important role in rubber interfacial lubrication and seal . So the relationship between interfacial contact pressure and real contact area ratio of rough rubber contact interface was measured and investigated with in situ observation instrument.…”

“…In certain engineering fields, the infiltration of fluid at this interface is the basis and premise of normal performance for rubber parts and whole mechanical equipment, for example, rubber friction and seal . For rubber friction interfaces, a high degree of fluid infiltration is required to reduce the interfacial friction force . However, fluid infiltration must be avoided completely to ensure the good sealing performance at rubber seal interfaces .…”

The Static Frictional Behaviors of Rubber for Pipe-Laying Operation

“…Tables 1 and 2 list the mechanical properties of rubber and pipe samples, respectively. Figure 3 illustrates a schematic view of the frictional testing instrument [22]. This testing instrument consists of three major systems, the X-direction loading component, the rubber-pipe contact testing component and the Y-direction loading component.…”

“…Its capacity is 0-250 N, and its accuracy is around 0.5%. The coefficient of friction of the linear slide rail is about 0.12 when normal load is zero, and it will not change more than 5% when Figure 3 illustrates a schematic view of the frictional testing instrument [22]. This testing instrument consists of three major systems, the X-direction loading component, the rubber-pipe contact testing component and the Y-direction loading component.…”

“…However, despite this progress, little attention has been paid to the project of static frictional behaviors of soft contact during deep water pipe-laying operations [22]. As is schematically shown in Figure 1, at the beginning of a pipe-laying operation, the pipeline is falling into the seawater by the pipe-laying tower with a preset velocity.…”