Kevlar is a type of aramid fibers which is characterized by high strength to low weight ratio. This material is widely used in bulletproof vests and helmets, in which it creates a barrier to projectiles to protect specific objectives, laminated tubes and pressure vessels, etc. In this study the ballistic behavior of Kevlar /epoxy composite and Kevlar fabric is investigated. The results showed t...

In many cases of heavy earthquakes, liquefaction has resulted in serious damages. Existing anisotropy in soil layers results  in some difficulties to realize the reason for these phenomena. Loose sand lenses buried in fine soils are one of the cases which may result in these problems and as a weak point during the earthquake can cause this phenomenon. In this paper, using FLAC 2D software, doub...

This paper presents a method for effectively modeling the outer surfaces of inlay/onlay prostheses restoring teeth that are partially destroyed. We exploit 3D mesh deformation techniques: direct manipulation free-form deformation (DMFFD) [9] and multiple wires deformation (MWD) [10] with three kinds of information: standard teeth models, scanned mesh data from the plaster cast of a patient's to...

We describe a group of alloys that exhibit "super" properties, such as ultralow elastic modulus, ultrahigh strength, super elasticity, and super plasticity, at room temperature and that show Elinvar and Invar behavior. These "super" properties are attributable to a dislocation-free plastic deformation mechanism. In cold-worked alloys, this mechanism forms elastic strain fields of hierarchical s...

Atomic force microscopy has recently provided highly precise measurements of mechanical properties of various viruses. However, molecular details underlying viral mechanics remain unresolved. Here we report atomic force microscopy nanoindentation experiments on T=4 hepatitis B virus (HBV) capsids combined with coarse-grained molecular dynamics simulations, which permit interpretation of experim...

Carbon nanotubes have the potential to construct highly compressible and elastic macroscopic structures such as films, aerogels and sponges. The structure-related deformation mechanism determines the mechanical behavior of those structures and niche applications. Here, we show a novel strategy to integrate aligned and random nanotube layers and reveal their deformation mechanism under uniaxial ...

Molecular dynamics deformation studies of nanocrystalline metals suggest a plasticity mechanism where dislocations are nucleated at grain boundaries (GB), travel through the grain being hindered by local GB stress intensities, to be finally absorbed in the surrounding GBs [1][2]. Recent constant strain rate molecular dynamics simulations of nanocrystalline Al demonstrated that dislocations can ...

Numerous articles describing the changes in structure and mechanical response of metals and alloys induced by shock waves have been published in the past twenty years (I-3). Increases in the concentration of point (4) and line defects (5), formation of twins (6), martensite (7) and precipitates (8) have been observed in the residual structures. Smith (9) proposed the f i rs t model accounting f...

A new experimental method, called the 'hole filling method', is proposed to simulate the healing of internal cracks in rolled workpieces. Based on the experimental results, the evolution in the microstructure, in terms of diffusion, nucleation and recrystallisation were used to analyze the crack healing mechanism. We also validated the phenomenon of segmented healing. Internal crack healing inv...

A comprehensive investigation of the mechanical behavior and microstructural evolution of carbon nanotube (CNT) continuous fibers under twisting and tension is conducted using coarse-grained molecular dynamics simulations. The tensile strength of CNT fibers with random CNT stacking is found to be higher than that of fibers with regular CNT stacking. The factor dominating the mechanical response...