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Numerous experiments on graphene, which is a 2D carbon material with excellent mechanical and electrical properties, have been carried out in recent years. By recognizing the properties of graphene, the researchers focused on other two-dimensional materials. Several studies have been done on graphene, but other two-dimensional structures have not yet been studied extensively. In this work, Germanene's simulation of molecular dynamics was performed and Germanene's stress–strain curve was obtained. The mechanical properties of Germanene have been investigated by practicing the proposed method of structural molecular mechanics. The two-step procedure was followed, where, in first step with the aid of the relations governing the force field and the Lifson–Wershel potential function and structural mechanics relations, the coefficients for the BEAM elements were found, and a structural mechanics model for Germanene was proposed. Then, a germanene sheet with 6 0 × 7 0 Ȧ was modeled and Young's modulus of Germanene was obtained by molecular dynamics and proposed molecular mechanics methods. [ABSTRACT FROM AUTHOR]

Graphene nanoplatelets (GNPs), the most important mass-produced graphene, are fabricated as a mechanical reinforcement for epoxy matrix nanocomposites. Current performance of GNPs as a reinforcing filler is limited by their agglomeration and weak interfacial interaction with certain polymer matrices. Herein, an approach to produce noncovalently functionalized GNPs (F-GNPs) is reported that can be extended to the industrial level of mass production. The one-step functionalization process uses melamine, a low-cost chemical, to improve the interfacial adhesion and dispersion in an epoxy matrix. The mechanical properties of nanocomposites prepared with the F-GNP flakes are much better (94.3% and 35.3% enhancements in Young's modulus and tensile strength, respectively) than those of the unfilled pure epoxy. Experimental data are analyzed using the Halpin-Tsai model. The fabrication process developed in this paper provides a strategy to use GNPs at the industrial level in lightweight and high-strength structural applications. [ABSTRACT FROM AUTHOR]

Polymer concrete (PC) has been widely used for quick repairing of concrete pavement and structures in recent years. This paper studies the mechanical behavior of the rubberized polymer concrete. Crumb and chipped rubber were used to replace fine and coarse aggregates in PC, respectively. A complete series of destructive tests including impact test, compression and splitting tensile tests and non-destructive methods including ultrasonic test, digital signal processing, electrical conductivity, and microstructure analysis was performed to demonstrate the various potential applications of the rubberized PC. X-ray diffraction (XRD) also provided information regarding the chemical composition and crystal structure of three different epoxy resin ratios. The results indicated that the rubberized PC reduced the workability and increased the porosity and air content of the mixture; however, reduced the cost and density, and improved ductility. Scanning electron microscope was used to analyze the interface between aggregates and adhesive materials. The correlation between the compressive strength and ultrasonic pulse velocity was determined and proposed for the rubberized PC. PC containing crumb rubber had a lower pulse velocity and higher damping properties than that of chipped rubber. Further, the Taguchi method was used to determine the optimum conditions for mechanical properties of the rubberized PC and ANOVA was then utilized to evaluate the level of influence and existence of interaction parameters. Based on this investigation, the rubberized PC can be an appropriate candidate for repair and rehabilitation applications. [ABSTRACT FROM AUTHOR]

Thermoplastic resin used as a matrix of fiber reinforced thermoplastics (FRTPs) is composed of high polymers that remain highly viscous even at a higher temperature than their melting points. As a result, they need a higher temperature, a higher pressure and longer process time to allow them to bond with fibers and consequently require large and specialized facilities. In this paper, a simple and fast fabrication method of vacuum assisted resin transfer molding (VARTM) method for hybrid fiber reinforced thermoplastic (HFRTP) was introduced. In order to fabricate HFRTP with the VARTM, glass and carbon fabrics were used as reinforcement and in-situ polymerizable epsilon caprolactam (ɛ-caprolactam) was used as the matrix. The obtained HFRTP had neither voids nor unfilled parts because the liquid state of ɛ-caprolactam was very low viscosity before polymerization. The fabrication method of the HFRTP proposed here showed a faster fabrication one compared with conventional fabrication methods. In order to apply this HFRTP to automotive structures, the performances of the HFRTP showed not only superior mechanical properties but also suitable for high-speed molding without expensive facilities, namely, within a few minute process time with a vacuum pump because they could be released from the mold without a cooling process. [ABSTRACT FROM AUTHOR]

In this paper, a novel computationally efficient multiscale framework based on the extended mechanics of structure genome (XMSG) is presented for predicting mechanical properties based on microstructure for Ti6Al4V parts fabricated by additive manufacturing (AM). The XMSG offers its novel capability to account for the effects of microstructure heterogeneity, porosity growth, and crack propagation for the multiscale calculations of the elastic/plastic/damage behavior of the AM parts in a computationally efficient manner. It is shown that XMSG can provide several orders of magnitude improvement in computational efficiency with the same level of accuracy compared to other conventional methods such as representative volume elements. The XMSG framework was applied to predict the tensile and compression behavior of AM Ti6Al4V, which showed very good agreement with the experimental results. In addition, the XMSG framework was able to predict the asymmetry in Young's modulus of the AM Ti6Al4V under tensile and compression loading as well as the anisotropy in the mechanical behavior under tension. • The proposed extended mechanics of structure genome is a novel computationally efficient multiscale homogenization method. • The method is used to successfully predict the mechanical behavior of additive manufactured Ti6Al4V with porosity. • The method is capable of predicting the anisotropy and asymmetry in the mechanical behaviors of Ti6Al4V. • The method is computationally superior to the existing homogenization method by more than two orders of magnitude. [ABSTRACT FROM AUTHOR]

In this article, the density functional theory is applied to characterize the mechanical properties of single-walled nanotubes of group IV of the periodic table. These materials include carbon nanotube, silicon nanotube, germanium nanotube, and stanene nanotube. (10,10) armchair nanotube is selected for the investigation. By establishing a link between potential energy expressions in molecular and structural mechanics, a finite element approach is proposed for modeling nanotubes. In the proposed model, the nanotubes are considered as an assemblage of beam elements. Young's modulus of the nanotubes is computed by the proposed finite element model. Young's modulus of carbon, silicon, germanium, and tin nanotubes are obtained as 1029, 159.82, 83.23, and 83.15 GPa, respectively, using the density functional theory. Also, the finite element approach gives the values as 1090, 154.67, 85.2, and 82.6 GPa, respectively. It is shown that the finite element model can predict the results of the density functional theory with good accuracy. [ABSTRACT FROM AUTHOR]

• A nonlinear molecular structural mechanics model is proposed for microtubules (MTs). • Lattice defect in MTs can reduce both their Young's modulus and fracture strain. • Predictive equations are developed for MTs with different lattice defect levels. A nonlinear molecular structural mechanics (MSM) model is proposed in this paper for studying the tensile properties of microtubules (MTs). In the nonlinear MSM models, the interactions between tubulin monomers in MTs are treated as nonlinear axial and torsional springs, whose stiffness coefficients are extracted from all-atom molecular dynamics simulations. The Young's modulus and fracture properties of MTs under tension extracted from the present nonlinear MSM models are found to agree well with the existing simulation and experiment results, which shows the efficiency and accuracy of the proposed nonlinear MSM models. In addition, the nonlinear MSM models are also extended to investigate the tensile properties including Young's modulus and fracture strain of MTs possessing lattice defects. The results obtained from nonlinear MSM models are utilized to develop a predictive equation for quickly predicting the tensile properties of MTs with different lattice defect levels. [ABSTRACT FROM AUTHOR]

In this study, a micro-molding technology was used to prepare the microneedles (MNs), while a texture analyzer was used to measure its Young's modulus, Poisson's ratio and compression breaking force, to evaluate whether the MNs can penetrate the skin. The effects of different materials were characterized by their ability to withstand stresses using the Structural Mechanics Module of COMSOL Multiphysics. Carboxymethylcellulose (CMC) was chosen as the needle formulation material with varying quantities of polyvinyl pyrrolidone (PVP), polyvinyl alcohol (PVA) and hyaluronic acid (HA) to adjust the viscosity, brittleness, hardness and solubility of the material. The results of both the experimental tests and the predictions indicated that the hardest tip material had a solids content of 15% ( w / w ) with a 1:2 ( w / w ) CMC: HA ratio. Furthermore, it was shown that a solid content of 10% ( w / w ) with a 1:5 ( w / w ) CMC: PVA ratio is suitable for making patches. The correlation between the mechanical properties and the different materials was found using the simulation analysis as well as the force required for different dissolving microneedles (DMNs) to penetrate the skin, which significantly promoted the research progress of microneedle transdermal drug delivery. [ABSTRACT FROM AUTHOR]