the present paper offers a meso-scale numerical model to investigate the effects of random distribution of aggregate particles and steel fibers on the elastic modulus of steel fiber reinforced concrete (sfrc). meso-scale model distinctively models coarse aggregate, cementitious mortar, and interfacial transition zone (itz) between aggregate, mortar, and steel fibers with their respective materi...

Crack propagation along one of the interfaces between a thin ductile adhesive layer and the elastic substrates it joins is considered. The layer is taken as being elastic-plastic, and the fracture process of the interface is modeled by a traction-separation law, characterized by the peak separation stress 6 and the work of separation per unit area To. Crack growth resistance curves for mode I l...

this study experimentally investigates the effect of multi-walled carbon nanotubes (mwnt’s), as a reinforcing material, on the physical properties of heavy-weight oil well cements. a candidate well is selected and the properties of the cement slurry used in a problematic section of the well are tested in the laboratory. carbon nanotubes (cnt’s) are added as fibers to the cement slurry and the i...

fiber metal laminates (fmls) are new composite materials consisting of thin metal layers and high strength composite layers. arall (aramid aluminum laminate) is a family of the fml that consists of thin aluminum sheets along with kevlar/epoxy composite layers. this material has many advantages such as light weight, excellent corrosion, fatigue and impact resistance. since, arall is a new materi...

A method to measure the mechanical behavior of Pt thin films was developed. It employs high magnification optical microscopy and Digital Image Correlation to extract sub-micron (100 nm local displacement resolution) deformation fields in free-standing thin films and calculate their elastic/plastic properties as a function of strain rate. In this study, the specimen gauge length and thickness we...

We present a phenomenological time-dependent Ginzburg-Landau theory of nonlinear plastic deformations in solids. Because the problem is very complex, we first give purely elastic models in one and two dimensions, where large strains produce densely distributed slips but the mass density deviations remain small except near the tips of slips. Next we set up a two-dimensional model including an or...

background: the aim of this study was to compare the effects of conventional acid etching and laser etching on the nano-mechanical properties of the dental enamel using nano-indentation test. materials and methods: in this experimental in vitro study, buccal surfaces of 10 premolars were divided into three regions. one of the regions was etched with 37% phosphoric acid and another etched with e...

The effect of differentiation on the transverse mechanical properties of mammalian myocytes was determined by using atomic force microscopy. The apparent elastic modulus increased from 11.5 +/- 1.3 kPa for undifferentiated myoblasts to 45.3 +/- 4.0 kPa after 8 days of differentiation (P < 0.05). The relative contribution of viscosity, as determined from the normalized hysteresis area, ranged fr...

We have experimentally determined the elastic properties of an individual multi-wall boron nitride (BN) nanotube. From the thermal vibration amplitude of a cantilevered BN nanotube observed in a transmission electron microscope, we find the axial Young's modulus to be 1.22 ± 0.24 TPa, a value consistent with theoretical estimates. The observed Young's modulus exceeds that of all other known ins...

We study the rheological behavior of mixtures of foams and pastes, which can be described as suspensions of bubbles in yield stress fluids. Model systems are designed by mixing monodisperse aqueous foams and concentrated emulsions. The elastic modulus of the bubble suspensions is found to depend on the elastic capillary number Ca G , defined as the ratio of the paste elastic modulus to the bubb...