The fracture of carbon nanotubes is studied by atomistic simulations. In these simulations, the fracture behavior is found to be almost independent of the separation energy and to depend primarily on the inflection point in the interatomic potential. The results show moderate dependence of fracture strength on chirality. The range of fracture strains compares well with experimental results, but...

We revisit in a 2d setting the notion of energy release rate, which plays a pivotal role in brittle fracture. Through a blow-up method, we extend that notion to crack patterns which are merely closed sets connected to the crack tip. As an application, we demonstrate that, modulo a simple meta-stability principle, a moving crack cannot generically kink while growing continuously in time. This la...

Wave-swept macroalgae are subjected to large hydrodynamic forces as each wave breaks on shore, loads that are repeated thousands of times per day. Previous studies have shown that macroalgae can easily withstand isolated impositions of maximal field forces. Nonetheless, macroalgae break frequently. Here we investigate the possibility that repeated loading by sub-lethal forces can eventually cau...

We find that the spoon-like tips of the chelipeds (large claws) of the crab Pachygrapsus crassipes differ from the rest of the claw in that they are not calcified, but instead contain about 1% bromine--thus they represent a new example of a class of structural biological materials that contain heavy elements such as Zn, Mn, Fe, Cu, and Br bound in an organic matrix. X-ray absorption spectroscop...

With the recent development of 3D printing technology, concrete materials are sometimes used in 3D printing. Concrete structures based on 3D printing have been characterized to have the form of multiple layer build-up. Unlike general concrete structures, therefore, the 3D-printed concrete can be regarded as an orthotropic material. The material property of the 3D-printed concrete’s interface be...

We review recent theories of non-classical, structured deformations and integral representations for their Helmholtz free energy. Energy minimizers for a body undergoing shearing at two di¤erent length scales and for a bar experiencing both smooth extension and macroscopic fractures then are determined, and applications to the shearing of single crystals and to the cohesive fracture of solids a...

The effect of interfacial friction on adhesion was studied by using a model system, in which a thin strip of silicone elastomer was peeled from a PDMS (poly(dimethylsiloxane)) treated glass slide. The fluorescent particle tracking method revealed that the elastomer stretches and slides on glass well before the crack faces open up. Interfacial energy dissipation due to friction, which is the pro...

Utilization of hydraulic-fracturing technology is dramatically increasing in exploitation of natural gas extraction. However the prediction of the configuration of propagated hydraulic fracture is extremely challenging. This paper presents a numerical method of obtaining the configuration of the propagated hydraulic fracture into discrete natural fracture network system. The method is developed...

A model is proposed, which predicts the toughness of 7000 series aluminium alloys in a variety of situations, including two alloy compositions, different quench rates from the solution treatment temperature and ageing states from underaged to overaged. The model is derived in three steps. The energy dissipated by transgranular fracture is first calculated, using a simplified cohesive zone appro...

We have done the numerical modeling of seismic response to multiple sets of vertical large fractures by using finite-difference method (FD), which can easily handle media with monoclinic anisotropy. We consider three types of fracture distributions: a set of parallel fractures, two sets of orthogonal fractures and two sets of non-orthogonal fractures intersecting at 45 degrees. We address the s...