Molecular dynamics (MD) simulations under transverse shear, uniaxial compression, and pullout loading configurations are reported for multiwall carbon nanotubes (MWCNTs) with different fraction of interwall sp3 bonds. The interwall shear coupling in MWCNTs is shown to have a strong influence on load transfer and compressive load carrying capacity. A new continuum shear-coupled-shell model is de...

A multilevel decomposition approach for the preliminary design of a High Speed Civil Transport Aircraft wing structure is described. The wing design is decomposed into three levels. The top level uses the FLOPS aircraft synthesis program to generate preliminary weights, mission, and performance information. The optimization criterion is productivity expressed by a productivity index for the spe...

The unique lattice structure and properties of graphene have drawn tremendous interests recently. By combining continuum and atomistic approaches, this paper investigates the mechanical properties of single-atomic-layer graphene sheets. A theoretical framework of nonlinear continuum mechanics is developed for graphene under both in-plane and bending deformation. Atomistic simulations are carrie...

The results of several perforated steel thin-walled U-shaped sections subject to compression are presented. The ultimate strength obtained from experimental tests is compared to the one obtained from numerical simulation by finite element method. The experimental tests were carried out according to the standard 10.2.02 of the FEM. The meshing, loading, boundary conditions for supports, geometri...

Composite steel shear wall is a lateral load resisting system which consists of a steel plate with concrete wall attached to one or both sides to prevent it from elastic buckling. The composite behavior is ensured by utilizing high-strength bolts. This paper investigates the effect of distance between bolts, and for this purpose 14 one-story one-bay specimens with various bolts spacing were mod...

When the out-of-plane stiffness of a beam is remarkably lower than the in-plane stiffness, the lateral-torsional buckling occurs. In this study, the behavior of mono-symmetric I-beams with discrete torsional and lateral bracings under the concentrated moment is investigated using the finite element analyses. Then, based on the numerical analyses, equation for the stiffness requirement is propos...

We introduce a novel concept for the design of programmable-elasticity metamaterials; materials whose elastic properties can be modified instantaneously and reversibly on demand. Real-time tunable linear and nonlinear elastic moduli are obtained in lattice materials by adjustment of strut connectivity via actuation of embedded electromagnetic locks. The Young’s modulus and Poisson’s ratio of pr...

C and Z sections are two of the most common cold-formed steel shapes in use today. Accurate prediction of the bending performance of these sections is important for reliable and efficient cold-formed steel structures. Recent analytical work has highlighted discontinuities and inconsistencies in the American Iron and Steel Institute ~AISI! and Canadian Standards Association ~S136! design provisi...