Improving the Flexural Response of Timber Beams Using Externally Bonded Carbon Fiber-Reinforced Polymer (CFRP) Sheets.

This paper presents a numerical investigation of the flexural behavior of timber beams externally strengthened with carbon-fiber-reinforced polymer (CFRP) sheets. At first, the accuracy of linear elastic and elastic-plastic models in predicting the behavior of bare timber beams was compared. Then, two modeling approaches (i.

Editorial: Microstructures and Mechanical Properties of Cement-Based Composites.

In recent years, with the fast development of the technology and the economy associated with the growth of the global population, the construction of economical, sustainable, and eco-friendly infrastructures with improved ductility, resistance to external elements, and durability has increased the need for the development of high-performance construction materials [...

Structure Design of GFRP Composite Leaf Spring: An Experimental and Finite Element Analysis.

Due to the high load-bearing capacity and light weight, composite leaf spring with variable width and variable thickness has been increasingly used in the automobile industry to replace the conventional steel leaf spring with a heavy weight. The optimum structural design of composite leaf spring is particularly favorable for the weight reduction. In this study, an effective algorithm is developed for structural optimization of composite leaf spring.

Coarse-grained molecular simulation of the effects of carbon nanotube dispersion on the mechanics of semicrystalline polymer nanocomposites.

With the incorporation of carbon nanotubes (CNTs), CNT/polypropylene (PP) nanocomposites are found to possess enhanced mechanical properties, but the reinforcing effect is reduced at large added CNT weight percentages due to CNT aggregation. Optimizing the properties of a nanocomposite requires a fundamental understanding of the effects of CNT dispersion on the nanocomposite. In this work, coarse-grained molecular models of CNT/PP nanocomposites are constructed, which consist of randomly dispersed or aggregated CNT bundles.

Understanding fracture behavior of epoxy-based polymer using molecular dynamics simulation.

With a network structure formed by cross-linking process, epoxy resins possess excellent mechanical properties. Among them, SU-8 photoresist (bisphenol-A epoxy resin) is widely used as coatings in microelectronic applications. This paper reports molecular dynamics simulations of the cross-linking process of SU-8 photoresist with detailed scripts and illustrates fracture behaviors of cross-linked network with in situ visualizations of atomistic details.

Understanding the Toughening Mechanism of Silane Coupling Agents in the Interfacial Bonding in Steel Fiber-Reinforced Cementitious Composites.

Interfacial bonding between a fiber and a matrix plays an essential role in composites, especially in fiber-reinforced cementitious composites that are superior forms for bearing flexural and tension load in construction applications. Yet, despite the importance, effective and economic approaches to improve the interfacial bonding between a steel fiber and a cementitious matrix remain unfeasible. Herein, we report a pathway adopting a silane coupling agent (SCA) to modify an interfacial transition zone (ITZ) and enhance interfacial bonding.

Experimental Investigation on Interfacial Defect Criticality of FRP-Confined Concrete Columns.

Defects between fiber reinforced polymer (FRP) and repaired concrete components may easily come out due to misoperation during manufacturing, environmental deterioration, or impact from external load during service life. The defects may cause a degraded structure performance and even the unexpected structural failure. Different non-destructive techniques (NDTs) and sensors have been developed to assess the defects in FRP bonded system.

Moisture effect on interfacial integrity of epoxy-bonded system: a hierarchical approach.

The epoxy-bonded system has been widely used in various applications across different scale lengths. Prior investigations have indicated that the moisture-affected interfacial debonding is the major failure mode of such a system, but the fundamental mechanism remains unknown, such as the basis for the invasion of water molecules in the cross-linked epoxy and the epoxy-bonded interface. This prevents us from predicting the long-term performance of the epoxy-related applications under the effect of the moisture.

Molecular Mechanics of the Moisture Effect on Epoxy/Carbon Nanotube Nanocomposites.

The strong structural integrity of polymer nanocomposite is influenced in the moist environment; but the fundamental mechanism is unclear, including the basis for the interactions between the absorbed water molecules and the structure, which prevents us from predicting the durability of its applications across multiple scales. In this research, a molecular dynamics model of the epoxy/single-walled carbon nanotube (SWCNT) nanocomposite is constructed to explore the mechanism of the moisture effect, and an analysis of the molecular interactions is provided by focusing on the hydrogen bond (H-bond) network inside the nanocomposite structure. The simulations show that at low moisture concentration, the water molecules affect the molecular interactions by favorably forming the water-nanocomposite H-bonds and the small cluster, while at high concentration the water molecules predominantly form the water-water H-bonds and the large cluster.