title: Interfacial shear strength in abalone nacre.
abstract: The shear strength of the interface between tiles of aragonite in the nacre of red abalone Haliotis rufescens was investigated through mechanical tensile and shear tests. Dog-bone shaped samples were used to determine the tensile strength of nacre when loaded parallel to the plane of growth; the mean strength was 65 MPa. Shear tests were conducted on a special fixture with a shear gap of 200 microm, approximately 100 microm narrower than the spacing between mesolayers. The shear strength is found to be 36.9+/-15.8 MPa with an average maximum shear strain of 0.3. Assuming the majority of failure occurs through tile pull-out and not through tile fracture, the tensile strength can be converted into a shear strength of 50.9 MPa. Three mechanisms of failure at the tile interfaces are discussed: fracture of mineral bridges, toughening due to friction created through nanoasperities, and toughening due to organic glue. An additional mechanism is fracture through individual tiles.
authors.affiliation: Materials Science and Engineering Program, University of California, San Diego, La Jolla, CA 92093-0411, USA. a5lin@ucsd.edu
authors.forename: Albert Yu-Min
authors.initials: AY
authors.lastname: Lin
authors.forename: Marc André
authors.initials: MA
authors.lastname: Meyers
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D049851:Gastropoda / Q000033:anatomy & histology*; D008855:Microscopy, Electron, Scanning; D033081:Shear Strength; D013718:Tensile Strength; D016474:Weight-Bearing