Wood is a multiscale material exhibiting a complex viscoplastic response. We study avalanches in small wood samples in compression. "Woodquakes" measured by acoustic emission are surprisingly similar to earthquakes and crackling noise in rocks and laboratory tests on brittle materials. Both the distributions of event energies and of waiting (silent) times follow power laws. The stress-strain re...

This paper addresses the coefficient of kinetic friction of relatively warm ice (-50 °C) sliding slowly (<1 m s) over itself and presents physical models to account for two characteristics: velocity-strengthening at lower speeds and velocity-weakening at higher speeds. The models are based upon a combination of creep deformation within a near-surface zone and frictional heating cum localized me...

new structural, metamorphic, finite strain and kinematic vorticity data for granitic gneiss and metavolcano-sedimentary rocks of thetanumaharea in the arabian shield in saudi arabia reveal a history of deformation reflecting different tectonic regimes. kinematic analysis shows their relationship to the nappe contacts between the granitic gneiss and metavolcano-sedimentary rocks and explains the...

The fracture toughness and strength of ceramics can be improved with respect to monolithic ceramics by developing graded materials as laminates composed of periodic alternating layers of one material separated by layers of a second material. The second layer must contain residual compressive stresses which are induced during densification because of differential thermal contraction of the layer...

background and objectives: kefiran (kef) is a water-soluble polysaccharide that can form transparent film however, it is brittle. therefore, in order to improve the mechanical properties of kefiran film, a mixture with other polymers can be offered. the expansion of mixed systems can propose kefiran and polyvinyl alcohol (pvoh) as a new composite film. materials and methods: solutions of 20 gra...

Anand & Gurtin (2002) have recently developed a continuum theory for the elasticviscoplastic deformation of amorphous solids. Their theory is motivated by and builds on the work of Parks, Argon, Boyce, Arruda, and their co-workers (e.g. Boyce et al., 1988; Arruda & Boyce, 1993) on modeling the plastic deformation of amorphous polymers. The theory of Anand & Gurtin (2002) carefully accounts for ...

Multivalent ions are known to allow for reversible cross-linking in soft biological materials, providing stiffness and extensibility via sacrificial bonds. We present a simple model where stiff nanoscale elements carrying negative charges are coupled in shear by divalent mobile cations in aqueous media. Such a shear coupling through a soft glue has, indeed, been proposed to operate in biologica...

Nacre from seashells, also known as mother-of-pearl, has attracted much attention for its remarkable mechanical properties despite the structural weaknesses of its components [1],[2]. In this article, in situ-tensile tests of dry and wet nacre dogbone specimens are presented. Optical microscopy and digital image correlation techniques were used to determine deformation and strain fields . While...

Talc is commonly found in the cores of exhumed faults and may be important to dynamics slip active fault zones. To understand rheology talc at conditions relevant subduction zones, we conducted torsional deformation experiments high pressure (1 GPa) temperatures (450–500°C). Scanning Transmission Electron Microscope imaging revealed a marked decrease grain size with increasing strain, addition ...