Wrinkling number and force of a particle raft in compression.

A particle raft is formed by a layer of small particles floating on a water surface, which has a higher load bearing capacity than pure water. In the present work, we have made a comprehensive study on the wrinkling number and force of the particle raft in planar compression. The wrinkling number during the whole loading process is measured, accompanied with snapshots on the morphologies of the particle raft. The force-displacement curve is given based on the loading system, which has been validated by the numerical simulation. Moreover, the experiment and theoretical results both show that the equivalent Young's modulus is dependent upon the loading displacement. Finally, the maximum wrinkling number of the raft has been analyzed by the scaling law, which agrees well with the experimental result. These findings have deepen our understandings on the mechanical properties of soft materials, which also hold implications on drug delivery, chemical engineering, micro-fluidics, environment protection, petroleum exploitation, mineral flotation, etc.