Self-amplification of solid friction in interleaved assemblies

Synopsis

Two interleaved phone books are virtually impossible to separate by pulling on their spines. This is an impressive example of solid friction in complex assemblies, a full understanding of which has remained elusive. Researchers have created a model that depends on parameters such as the number of sheets, their thickness, and the area of page-overlap. They then compared their model to results of experiments performed on controlled booklets. The model predicted, and the experiments demonstrated, the force required to separate the booklets increased sharply with the number of pages. The results of this research could provide insight into complex intertwined systems such as textiles or muscle fibres.