Finite element stiffness and consistent mass matrices are derived for helically wound, symmetrical composite tubes. The tubular element is considered to have constant cross-section and small deformations restricted to a plane. Each node has three degrees of freedom: axial and transverse displacement and rotation (slope of transverse displacement). Shell theory and lamination theory are used to ...

Fibers and yarns based on carbon nanotubes (CNT) are emerging as a possible improvement over more traditional high strength carbon fibers used as reinforcement elements in composite materials. This is driven by a desire to translate the exceptional mechanical properties of individual CNT shells to achieve high performance macroscopic fibers and yarns. One of the central limitations in this appr...

The assessment of response of composite seismic force resisting systems requires accurate nonlinear formulations for the composite members. In this work, reporting the first phase of a NEES project, a three-dimensional distributed plasticity formulation is presented for both circular and rectangular composite concrete-filled steel tubes (CFTs) that includes new constitutive models for the concr...

Secondary caries are a worldwide public and socioeconomic problem. The placement of restorations can lead to the development of environmental conditions favorable to microbial colonization, especially on the tooth/restoration interface, which is a predisposing factor for secondary caries. The aim of this study was to evaluate microbial retention on conventional (Chelon-Fil and Vidrion R) and re...

An in situ composite synthesis technique has been developed by grafting polystyrene chains onto single-wall carbon nanotubes (SWNTs) via a single-step debundling/polymerization scheme. The method, based on established anionic polymerization techniques, eliminates the need for nanotube pretreatment prior to functionalization and allows attachment of polymer molecules to pristine tubes without al...

In summary, we have presented a suitable approach to obtain surfactant-stabilized suspensions of long, individually dispersed SWCNTs essentially free of bundles. The combination of mild tip and bath ultrasonication has proven effective in unbundling the SWCNT ropes and, at the same time, in minimizing tube shortening. This method is expected to be useful for applications that critically depend ...

Concrete filled tubes (CFTs) composite columns have many economical and esthetic advantages, but the behavior of their connections is complicated. Through this study, it is aimed to investigate the performance and behavior of different connection configurations between concrete filled steel tube columns and bracing diagonals through an experimental program. The study included 12 connection suba...