Local strain fields in paper

When a paper specimen is strained microscopic ruptures give rise to plastic deformations. These deformations can be made visible by silicone impregnation. We show that the plastic deformations or strains are nonuniform on the microscopic and macroscopic scale. Large fractions of a typical paper specimen do not enter the plastic region before rupture, even though the macroscopic behavior may be highly plastic. Computer simulations are employed to evaluate the macroscopic strain variations and the changes in paper properties that are induced by formation-type disorder. We show that increasing disorder reduces the number of plastic yield sites.